tsdb: fix prometheus_tsdb_head_chunks going negative after WAL replay by jcreixell · Pull Request #18401 · prometheus/prometheus

jcreixell · 2026-03-30T11:57:34Z

Note

I used Claude to track down this bug, with the purpose of learning more about the tsdb, mostly for educational purposes and to be able to contribute more in the future.

What this fixes

prometheus_tsdb_head_chunks (computed as chunksCreated − chunksRemoved) can go negative after a
restart when a stale series is truncated and the same label set is immediately re-created.

Root cause

deleteSeriesByID is called during WAL replay when a full-range tombstone [MinInt64, MaxInt64] is
encountered (written by truncateStaleSeries). It correctly subtracts len(series.mmappedChunks)
from the gauge, but does not clear series.mmappedChunks.

When the same label set is re-created in the same WAL segment, both the old and new Series
records map to the same memSeries pointer. Both reset items and the delete item land in the same
processor shard (routed by ref % concurrency), giving this FIFO queue:

  [1] reset(mSeries, M mmappedChunks, walRef=old)  →  gauge += M
  [2] deleteSeriesByID(old)                         →  gauge -= M  (but mmappedChunks still = M)
  [3] reset(mSeries, N mmappedChunks, walRef=new)   →  gauge -= M again  ← double-subtract

When M > N the gauge goes negative.

Fix

Set series.mmappedChunks = nil in deleteSeriesByID immediately after accounting for those
chunks. Step [3] then sees zero old chunks and subtracts nothing.

Note: this is an alternative fix to (#17775).

Which issue(s) does the PR fix:

Fixes #10884

Release notes for end users (ALL commits must be considered).

Reviewers should verify clarity and quality.

[BUGFIX] TSDB: fix prometheus_tsdb_head_chunks going negative after WAL replay

When truncateStaleSeries deletes a series (writing a full-range tombstone to the WAL) and the same label set is immediately re-created, WAL replay queues the following sequence on the same processor shard for the shared memSeries pointer: reset(mSeries, M mmappedChunks, walRef=old) deleteSeriesByID(old) reset(mSeries, N mmappedChunks, walRef=new) deleteSeriesByID correctly subtracts M from the gauge but does not clear series.mmappedChunks. The subsequent reset subtracts M again, driving prometheus_tsdb_head_chunks negative when M > N. Fix by setting series.mmappedChunks = nil in deleteSeriesByID after accounting for those chunks. Fixes prometheus#10884 Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com> Signed-off-by: Jorge Creixell <jcreixell@gmail.com>

- Re-use appending helper - Cleanup comments Signed-off-by: Jorge Creixell <jcreixell@gmail.com>

Signed-off-by: Jorge Creixell <jcreixell@gmail.com>

krajorama

Approved with nit.
I'm not 100% following what happens, but the test is convincing and we do remove the chunk from lookup before we clear mmapedChunks.
The one thing that could maybe go wrong is if we built chunk meta references to these chunks in a query, but as far as I can tell, we don't allow queries during WAL replay.
And even if we allowed it, the query would handle missing mmapped chunk somewhat gracefully I think.

Co-authored-by: George Krajcsovits <krajorama@users.noreply.github.com> Signed-off-by: Jorge Creixell <jcreixell@gmail.com>

jcreixell · 2026-03-31T19:29:41Z

Thanks for the review @krajorama.

In case it helps, here is my understanding of what happens.

Recreating the head involves (among other things, sequentially):

loadMmappedChunks — reads all m-mapped chunk files from disk into memory, populates
series.mmappedChunks
WAL replay — processes series/sample/tombstone records
- During WAL replay, each series record triggers resetSeriesWithMMappedChunks, which wires up the
  pre-loaded m-mapped chunks to the memSeries and updates the gauge.
- A tombstone triggers deleteSeriesByID, which subtracts those chunks and removes the series from
  the lookup maps.
- A re-registration (the series came back after its ref was deleted) leads to a subsequent resetSeriesWithMMappedChunks call.

The bug arises when the same label set is re-created after the tombstone: the WAL contains two
series records for the same memSeries (ref1 and ref2), with the tombstone in between. The
processor queue for that shard looks like:

[1] reset(mSeries, ref1) → subtract 0 old, add M new → gauge += M
[2] deleteSeriesByID(ref1) → gauge -= M ✓
[3] reset(mSeries, ref2) → subtract M old (stale!), add 0 new → gauge -= M ✗

…prometheus#18401) * tsdb: fix prometheus_tsdb_head_chunks going negative after WAL replay When truncateStaleSeries deletes a series (writing a full-range tombstone to the WAL) and the same label set is immediately re-created, WAL replay queues the following sequence on the same processor shard for the shared memSeries pointer: reset(mSeries, M mmappedChunks, walRef=old) deleteSeriesByID(old) reset(mSeries, N mmappedChunks, walRef=new) deleteSeriesByID correctly subtracts M from the gauge but does not clear series.mmappedChunks. The subsequent reset subtracts M again, driving prometheus_tsdb_head_chunks negative when M > N. Fix by setting series.mmappedChunks = nil in deleteSeriesByID after accounting for those chunks. Fixes prometheus#10884 Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com> Signed-off-by: Jorge Creixell <jcreixell@gmail.com> * Simplify test - Re-use appending helper - Cleanup comments Signed-off-by: Jorge Creixell <jcreixell@gmail.com> * Improve comments in test Signed-off-by: Jorge Creixell <jcreixell@gmail.com> * Fix formatting Signed-off-by: Jorge Creixell <jcreixell@gmail.com> * Improve comment Co-authored-by: George Krajcsovits <krajorama@users.noreply.github.com> Signed-off-by: Jorge Creixell <jcreixell@gmail.com> --------- Signed-off-by: Jorge Creixell <jcreixell@gmail.com> Co-authored-by: George Krajcsovits <krajorama@users.noreply.github.com> Signed-off-by: Raphael Bizos <r.bizos@criteo.com>

…➔ v3.12.0) (#730) This PR contains the following updates: | Package | Update | Change | |---|---|---| | [quay.io/prometheus/prometheus](https://github.com/prometheus/prometheus) | minor | `v3.11.3` → `v3.12.0` | --- ### Release Notes <details> <summary>prometheus/prometheus (quay.io/prometheus/prometheus)</summary> ### [`v3.12.0`](https://github.com/prometheus/prometheus/releases/tag/v3.12.0): 3.12.0 / 2026-05-28 [Compare Source](prometheus/prometheus@v3.11.3...v3.12.0) - \[SECURITY] Remote-write: Reject snappy-compressed requests whose declared decoded length exceeds the 32MB. Thanks to [@hibrian827](https://github.com/hibrian827) for reporting it. [#18642](prometheus/prometheus#18642) - \[SECURITY] STACKIT SD: Fix secrets being exposed in plaintext via `/-/config` endpoint. Thanks to [@August829](https://github.com/August829) and [@Phaxma](https://github.com/Phaxma) for reporting. GHSA-39j6-789q-qxvh [#18649](prometheus/prometheus#18649) - \[CHANGE] TSDB/Agent: Adds Start Timestamp field to all WAL Histogram samples in memory; used `st-storage` flag is enabled. [#18221](prometheus/prometheus#18221) - \[FEATURE] API: Add `/api/v1/status/self_metrics` endpoint returning the current state of the Prometheus server's own metrics about itself as JSON. [#18411](prometheus/prometheus#18411) - \[FEATURE] Discovery: Add DigitalOcean Managed Databases service discovery [#18287](prometheus/prometheus#18287) - \[FEATURE] Prometheus: Add support for the aix/ppc64 compilation target [#18321](prometheus/prometheus#18321) - \[FEATURE] Discovery: Add Outscale VM service discovery (`outscale_sd_configs`) for discovering scrape targets from the Outscale Cloud API. [#18139](prometheus/prometheus#18139) - \[FEATURE] PromQL: Emit a warning when `sort`, `sort_by_label` or `sort_by_label_desc` is used within range (matrix) queries, as these functions do not have effect in that context. [#18498](prometheus/prometheus#18498) - \[FEATURE] PromQL: Add `start()`, `end()`, `range()`, and `step()` experimental functions [#17877](prometheus/prometheus#17877) - \[FEATURE] PromQL: Update `resets()` function to consider start timestamp resets. Hidden behind `use-start-timestamps` feature flag. [#18627](prometheus/prometheus#18627) - \[FEATURE] Prometheus: Promote auto-reload-config as stable [#18620](prometheus/prometheus#18620) - \[FEATURE] TSDB/Agent: Add `CheckpointFromInMemorySeries` option to `agent.DB` that enables checkpoint based on in-memory series. [#17948](prometheus/prometheus#17948) - \[FEATURE] UI: Add a web interface for deleting time series and cleaning tombstones, accessible from the Status menu. [#18390](prometheus/prometheus#18390) - \[FEATURE] PromQL: Use start timestamps for `rate()`, `irate(), and `increase()`calculations, behind a feature flag`use-start-timestamps`. Doesn't work together with extended range selectors `anchored`and`smoothed\`. [#18344](prometheus/prometheus#18344) - \[FEATURE] Scrape: Added a feature flag `st-synthesis` which synthesizes unknown STs for scraped cumulative metrics. Useful when Remote Writing 2.0 with delta or Otel-based backends. [#18279](prometheus/prometheus#18279) - \[FEATURE] promqltest: support `@st` annotation in `load` blocks to specify per-sample start timestamps. [#18360](prometheus/prometheus#18360) - \[ENHANCEMENT] API: reject concurrent fgprof profiles. [#18651](prometheus/prometheus#18651) - \[ENHANCEMENT] AWS SD: Add optional `external_id` field to ECS/MSK/RDS/Elasticache. [#18579](prometheus/prometheus#18579) - \[ENHANCEMENT] AWS SD: Add optional `external_id` field. [#17171](prometheus/prometheus#17171) - \[ENHANCEMENT] Discovery: Propagate SD target updates faster by introducing dynamic backoff interval instead of static 5s interval for throttling. [#18187](prometheus/prometheus#18187) - \[ENHANCEMENT] Promtool: Add `--header` flag to `query instant` command, matching existing `query range` behaviour. [#18418](prometheus/prometheus#18418) - \[ENHANCEMENT]: AWS SD: Allows EC2 service discovery to discover IPv6 addresses to communicate with target endpoints. The private IPv4 address remains the default when both IPv4 and IPv6 addresses are present. [#16088](prometheus/prometheus#16088) - \[PERF] TSDB: Make head chunk lookup in range queries constant time instead of quadratic time [#18302](prometheus/prometheus#18302) - \[PERF] TSDB: Skip entire stripes in mmapHeadChunks when no series need mmapping, reducing CPU utilization significantly at production-relevant scales. [#18541](prometheus/prometheus#18541) - \[PERF] TSDB: Skip clean series during periodic head chunk mmap using cached head chunk count [#18272](prometheus/prometheus#18272) - \[PERF] PromQL: Address FloatHistogram.KahanAdd performance regression on Go 1.26. [#18568](prometheus/prometheus#18568) - \[BUGFIX] PromQL: Fix `info()` function incorrectly handling negated `__name__` matchers [#17932](prometheus/prometheus#17932) - \[BUGFIX] API: Return duration expressions in `/parse_ast`. [#18624](prometheus/prometheus#18624) - \[BUGFIX] API: correctly document formats accepted for duration query request parameters (step, timeout and lookback delta) in OpenAPI spec [#18305](prometheus/prometheus#18305) - \[BUGFIX] Scrape: AppenderV2 now tracks staleness even when OOO/duplicate series errors happen similar to AppenderV1 [#18567](prometheus/prometheus#18567) - \[BUGFIX] Config: Validate remote\_write queue\_config fields at load time to prevent runtime panic and silent misconfiguration. [#18209](prometheus/prometheus#18209) - \[BUGFIX] Discovery/Consul: Add `health_filter` for Health API filtering, fixing breakage when using Catalog-only fields like `ServiceTags` in `filter`. [#18479](prometheus/prometheus#18479) [#18499](prometheus/prometheus#18499) - \[BUGFIX] OTLP: limit decompressed body size for gzip-encoded OTLP write requests. [#18408](prometheus/prometheus#18408) - \[BUGFIX] PromQL: Fix `smoothed` rate/increase returning zero instead of no result when all data falls strictly after the query range. [#18523](prometheus/prometheus#18523) - \[BUGFIX] PromQL: Fix metric name not being dropped when last\_over\_time or first\_over\_time is applied to subqueries containing name-dropping functions like abs(). [#18409](prometheus/prometheus#18409) - \[BUGFIX] PromQL: Fix missing warning when mixing exponential and custom-bucket histograms in stats queries. [#18660](prometheus/prometheus#18660) - \[BUGFIX] PromQL: Fix parsing of `range()` keyword in duration expressions such as `foo[5m+range()]`. [#18623](prometheus/prometheus#18623) - \[BUGFIX] PromQL: Fix smoothed vector selector returning no results in binary operations when the `@` modifier is used. [#18531](prometheus/prometheus#18531) - \[BUGFIX] PromQL: Reject NaN, infinite, and out-of-range duration expressions instead of silently producing an out-of-range time.Duration. [#18639](prometheus/prometheus#18639) - \[BUGFIX] Scrape: Fix panic when scraping malformed native histograms. [#18414](prometheus/prometheus#18414) - \[BUGFIX] Scrape: fix panic when scraping a target exposing a summary with no quantiles via the protobuf format. [#18382](prometheus/prometheus#18382) - \[BUGFIX] Scrape: fix scrape failure log file occasionally not applied after a configuration reload. [#18421](prometheus/prometheus#18421) - \[BUGFIX] TSDB: Allow retention percentage with new data path. [#18628](prometheus/prometheus#18628) - \[BUGFIX] TSDB: Preserve decimal precision in percentage-based retention [#18374](prometheus/prometheus#18374) - \[BUGFIX] TSDB: fix prometheus\_tsdb\_head\_chunks going negative after WAL replay [#18401](prometheus/prometheus#18401) - \[BUGFIX] TSDB: panic with native histograms during query of overlapping chunks. [#18692](prometheus/prometheus#18692) - \[BUGFIX] Tracing: fix startup failure for insecure OTLP HTTP tracing [#18469](prometheus/prometheus#18469) - \[BUGFIX] UI: Escape label values offered by PromQL autocomplete. [#18658](prometheus/prometheus#18658) - \[BUGFIX] UI: Improve Y-axis tick label precision for graph values over small ranges. [#18682](prometheus/prometheus#18682) - \[BUGFIX] `prometheus_sd_refresh*` and `prometheus_sd_discovered_targets` metrics for specific scrape jobs are deleted when the scrape job is removed. [#17614](prometheus/prometheus#17614) - \[BUGFIX] Remote: fixed validation for received RW2 requests when parsing metadata unit symbols. This fixes a case when request would cause (recovered) handler panic. [#18641](prometheus/prometheus#18641) - \[BUGFIX] TSDB/Agent: fix race in agent appender where concurrent appends for the same label set could produce duplicate in-memory series and duplicate WAL records. [#18292](prometheus/prometheus#18292) - \[BUGFIX] Config: Update `--enable-feature` flag description and sort feature names. [#18487](prometheus/prometheus#18487) </details> --- ### Configuration 📅 **Schedule**: Branch creation - At any time (no schedule defined), Automerge - At any time (no schedule defined). 🚦 **Automerge**: Disabled by config. Please merge this manually once you are satisfied. ♻ **Rebasing**: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox. 🔕 **Ignore**: Close this PR and you won't be reminded about these updates again. --- - [ ] If you want to rebase/retry this PR, check this box --- This PR has been generated by [Renovate Bot](https://github.com/renovatebot/renovate).  Reviewed-on: https://git.erwanleboucher.dev/eleboucher/homelab/pulls/730

@hibrian827

##### [\`v3.12.0\`](https://github.com/prometheus/prometheus/releases/tag/v3.12.0) This release contains security fixes, new features (especially around PromQL and Service Discovery), performance improvements in TSDB, Start Timestamp improvements and numerous bug fixes. Thanks to all contributors! #### Key Highlights - **Security**: Two security vulnerabilities have been addressed: a denial of service in remote-write (snappy decompression limit) and a secret exposure leak in STACKIT service discovery. - **PromQL & Metadata**: Several features and bug fixes related to the experimental "start timestamps" support, including updates to `rate()`, `irate()`, `increase()`, and `resets()`. New experimental functions `start()`, `end()`, `range()`, and `step()` are introduced. - **TSDB Performance**: Optimizations in head chunk lookup (constant time) and mmap operations to reduce CPU usage. - **Service Discovery**: Added support for DigitalOcean Managed Databases and Outscale VM, along with improvements to AWS SD (IPv6 support for EC2, external ID support). - **UI**: Added a web interface for deleting time series and cleaning tombstones. #### Changelog - \[SECURITY] Remote: Reject snappy-compressed received requests via Remote Write whose declared decoded length exceeds the 32MB. Thanks to [@hibrian827](https://github.com/hibrian827) for reporting it. [#18642](prometheus/prometheus#18642) - \[SECURITY] STACKIT SD: Fix secrets being exposed in plaintext via `/-/config` endpoint. Thanks to [@August829](https://github.com/August829) and [@Phaxma](https://github.com/Phaxma) for reporting. GHSA-39j6-789q-qxvh [#18649](prometheus/prometheus#18649) - \[CHANGE] TSDB/Agent: Adds Start Timestamp field to all WAL Histogram samples in memory; used `st-storage` flag is enabled. [#18221](prometheus/prometheus#18221) - \[FEATURE] API: Add `/api/v1/status/self_metrics` endpoint returning the current state of the Prometheus server's own metrics about itself as JSON. [#18411](prometheus/prometheus#18411) - \[FEATURE] Discovery: Add DigitalOcean Managed Databases service discovery [#18287](prometheus/prometheus#18287) - \[FEATURE] Prometheus: Add support for the aix/ppc64 compilation target [#18321](prometheus/prometheus#18321) - \[FEATURE] Discovery: Add Outscale VM service discovery (`outscale_sd_configs`) for discovering scrape targets from the Outscale Cloud API. [#18139](prometheus/prometheus#18139) - \[FEATURE] PromQL: Emit a warning when `sort`, `sort_by_label` or `sort_by_label_desc` is used within range (matrix) queries, as these functions do not have effect in that context. [#18498](prometheus/prometheus#18498) - \[FEATURE] PromQL: Add `start()`, `end()`, `range()`, and `step()` experimental functions [#17877](prometheus/prometheus#17877) - \[FEATURE] PromQL: Update `resets()` function to consider start timestamp resets. Hidden behind `use-start-timestamps` feature flag. [#18627](prometheus/prometheus#18627) - \[FEATURE] Prometheus: Promote auto-reload-config as stable [#18620](prometheus/prometheus#18620) - \[FEATURE] TSDB/Agent: Add `CheckpointFromInMemorySeries` option to `agent.DB` that enables checkpoint based on in-memory series. [#17948](prometheus/prometheus#17948) - \[FEATURE] UI: Add a web interface for deleting time series and cleaning tombstones, accessible from the Status menu. [#18390](prometheus/prometheus#18390) - \[FEATURE] PromQL: Use start timestamps for `rate()`, `irate()`, and `increase()` calculations, behind a feature flag `use-start-timestamps`. Doesn't work together with extended range selectors `anchored` and `smoothed`. [#18344](prometheus/prometheus#18344) - \[FEATURE] Scrape: Added a feature flag `st-synthesis` which synthesizes unknown STs for scraped cumulative metrics. Useful when Remote Writing 2.0 with delta or Otel-based backends. [#18279](prometheus/prometheus#18279) - \[FEATURE] promqltest: support `@st` annotation in `load` blocks to specify per-sample start timestamps. [#18360](prometheus/prometheus#18360) - \[ENHANCEMENT] API: reject concurrent fgprof profiles. [#18651](prometheus/prometheus#18651) - \[ENHANCEMENT] AWS SD: Add optional `external_id` field to ECS/MSK/RDS/Elasticache. [#18579](prometheus/prometheus#18579) - \[ENHANCEMENT] AWS SD: Add optional `external_id` field. [#17171](prometheus/prometheus#17171) - \[ENHANCEMENT] Discovery: Propagate SD target updates faster by introducing dynamic backoff interval instead of static 5s interval for throttling. [#18187](prometheus/prometheus#18187) - \[ENHANCEMENT] Promtool: Add `--header` flag to `query instant` command, matching existing `query range` behaviour. [#18418](prometheus/prometheus#18418) - \[ENHANCEMENT]: AWS SD: Allows EC2 service discovery to discover IPv6 addresses to communicate with target endpoints. The private IPv4 address remains the default when both IPv4 and IPv6 addresses are present. [#16088](prometheus/prometheus#16088) - \[PERF] TSDB: Make head chunk lookup in range queries constant time instead of quadratic time [#18302](prometheus/prometheus#18302) - \[PERF] TSDB: Skip entire stripes in mmapHeadChunks when no series need mmapping, reducing CPU utilization significantly at production-relevant scales. [#18541](prometheus/prometheus#18541) - \[PERF] TSDB: Skip clean series during periodic head chunk mmap using cached head chunk count [#18272](prometheus/prometheus#18272) - \[PERF] PromQL: Address FloatHistogram.KahanAdd performance regression on Go 1.26. [#18568](prometheus/prometheus#18568) - \[BUGFIX] PromQL: Fix `info()` function incorrectly handling negated `__name__` matchers [#17932](prometheus/prometheus#17932) - \[BUGFIX] API: Return duration expressions in `/parse_ast`. [#18624](prometheus/prometheus#18624) - \[BUGFIX] API: correctly document formats accepted for duration query request parameters (step, timeout and lookback delta) in OpenAPI spec [#18305](prometheus/prometheus#18305) - \[BUGFIX] Scrape: AppenderV2 now tracks staleness even when OOO/duplicate series errors happen similar to AppenderV1 [#18567](prometheus/prometheus#18567) - \[BUGFIX] Config: Validate remote\_write queue\_config fields at load time to prevent runtime panic and silent misconfiguration. [#18209](prometheus/prometheus#18209) - \[BUGFIX] Discovery/Consul: Add `health_filter` for Health API filtering, fixing breakage when using Catalog-only fields like `ServiceTags` in `filter`. [#18479](prometheus/prometheus#18479) [#18499](prometheus/prometheus#18499) - \[BUGFIX] OTLP: limit decompressed body size for gzip-encoded OTLP write requests. [#18408](prometheus/prometheus#18408) - \[BUGFIX] PromQL: Fix `smoothed` rate/increase returning zero instead of no result when all data falls strictly after the query range. [#18523](prometheus/prometheus#18523) - \[BUGFIX] PromQL: Fix metric name not being dropped when last\_over\_time or first\_over\_time is applied to subqueries containing name-dropping functions like abs(). [#18409](prometheus/prometheus#18409) - \[BUGFIX] PromQL: Fix missing warning when mixing exponential and custom-bucket histograms in stats queries. [#18660](prometheus/prometheus#18660) - \[BUGFIX] PromQL: Fix parsing of `range()` keyword in duration expressions such as `foo[5m+range()]`. [#18623](prometheus/prometheus#18623) - \[BUGFIX] PromQL: Fix smoothed vector selector returning no results in binary operations when the `@` modifier is used. [#18531](prometheus/prometheus#18531) - \[BUGFIX] PromQL: Reject NaN, infinite, and out-of-range duration expressions instead of silently producing an out-of-range time.Duration. [#18639](prometheus/prometheus#18639) - \[BUGFIX] Scrape: Fix panic when scraping malformed native histograms. [#18414](prometheus/prometheus#18414) - \[BUGFIX] Scrape: fix panic when scraping a target exposing a summary with no quantiles via the protobuf format. [#18382](prometheus/prometheus#18382) - \[BUGFIX] Scrape: fix scrape failure log file occasionally not applied after a configuration reload. [#18421](prometheus/prometheus#18421) - \[BUGFIX] TSDB: Allow retention percentage with new data path. [#18628](prometheus/prometheus#18628) - \[BUGFIX] TSDB: Preserve decimal precision in percentage-based retention [#18374](prometheus/prometheus#18374) - \[BUGFIX] TSDB: fix prometheus\_tsdb\_head\_chunks going negative after WAL replay [#18401](prometheus/prometheus#18401) - \[BUGFIX] TSDB: panic with native histograms during query of overlapping chunks. [#18692](prometheus/prometheus#18692) - \[BUGFIX] Tracing: fix startup failure for insecure OTLP HTTP tracing [#18469](prometheus/prometheus#18469) - \[BUGFIX] UI: Escape label values offered by PromQL autocomplete. [#18658](prometheus/prometheus#18658) - \[BUGFIX] UI: Improve Y-axis tick label precision for graph values over small ranges. [#18682](prometheus/prometheus#18682) - \[BUGFIX] `prometheus_sd_refresh*` and `prometheus_sd_discovered_targets` metrics for specific scrape jobs are deleted when the scrape job is removed. [#17614](prometheus/prometheus#17614) - \[BUGFIX] Remote: fixed validation for received RW2 requests when parsing metadata unit symbols. This fixes a case when request would cause (recovered) handler panic. [#18641](prometheus/prometheus#18641) - \[BUGFIX] TSDB/Agent: fix race in agent appender where concurrent appends for the same label set could produce duplicate in-memory series and duplicate WAL records. [#18292](prometheus/prometheus#18292) - \[BUGFIX] Config: Update `--enable-feature` flag description and sort feature names. [#18487](prometheus/prometheus#18487)

@hibrian827

##### [\`v3.12.0\`](https://github.com/prometheus/prometheus/releases/tag/v3.12.0) This release contains security fixes, new features (especially around PromQL and Service Discovery), performance improvements in TSDB, Start Timestamp improvements and numerous bug fixes. Thanks to all contributors! #### Key Highlights - **Security**: Two security vulnerabilities have been addressed: a denial of service in remote-write (snappy decompression limit) and a secret exposure leak in STACKIT service discovery. - **PromQL & Metadata**: Several features and bug fixes related to the experimental "start timestamps" support, including updates to `rate()`, `irate()`, `increase()`, and `resets()`. New experimental functions `start()`, `end()`, `range()`, and `step()` are introduced. - **TSDB Performance**: Optimizations in head chunk lookup (constant time) and mmap operations to reduce CPU usage. - **Service Discovery**: Added support for DigitalOcean Managed Databases and Outscale VM, along with improvements to AWS SD (IPv6 support for EC2, external ID support). - **UI**: Added a web interface for deleting time series and cleaning tombstones. #### Changelog - \[SECURITY] Remote: Reject snappy-compressed received requests via Remote Write whose declared decoded length exceeds the 32MB. Thanks to [@hibrian827](https://github.com/hibrian827) for reporting it. [#18642](prometheus/prometheus#18642) - \[SECURITY] STACKIT SD: Fix secrets being exposed in plaintext via `/-/config` endpoint. Thanks to [@August829](https://github.com/August829) and [@Phaxma](https://github.com/Phaxma) for reporting. GHSA-39j6-789q-qxvh [#18649](prometheus/prometheus#18649) - \[CHANGE] TSDB/Agent: Adds Start Timestamp field to all WAL Histogram samples in memory; used `st-storage` flag is enabled. [#18221](prometheus/prometheus#18221) - \[FEATURE] API: Add `/api/v1/status/self_metrics` endpoint returning the current state of the Prometheus server's own metrics about itself as JSON. [#18411](prometheus/prometheus#18411) - \[FEATURE] Discovery: Add DigitalOcean Managed Databases service discovery [#18287](prometheus/prometheus#18287) - \[FEATURE] Prometheus: Add support for the aix/ppc64 compilation target [#18321](prometheus/prometheus#18321) - \[FEATURE] Discovery: Add Outscale VM service discovery (`outscale_sd_configs`) for discovering scrape targets from the Outscale Cloud API. [#18139](prometheus/prometheus#18139) - \[FEATURE] PromQL: Emit a warning when `sort`, `sort_by_label` or `sort_by_label_desc` is used within range (matrix) queries, as these functions do not have effect in that context. [#18498](prometheus/prometheus#18498) - \[FEATURE] PromQL: Add `start()`, `end()`, `range()`, and `step()` experimental functions [#17877](prometheus/prometheus#17877) - \[FEATURE] PromQL: Update `resets()` function to consider start timestamp resets. Hidden behind `use-start-timestamps` feature flag. [#18627](prometheus/prometheus#18627) - \[FEATURE] Prometheus: Promote auto-reload-config as stable [#18620](prometheus/prometheus#18620) - \[FEATURE] TSDB/Agent: Add `CheckpointFromInMemorySeries` option to `agent.DB` that enables checkpoint based on in-memory series. [#17948](prometheus/prometheus#17948) - \[FEATURE] UI: Add a web interface for deleting time series and cleaning tombstones, accessible from the Status menu. [#18390](prometheus/prometheus#18390) - \[FEATURE] PromQL: Use start timestamps for `rate()`, `irate()`, and `increase()` calculations, behind a feature flag `use-start-timestamps`. Doesn't work together with extended range selectors `anchored` and `smoothed`. [#18344](prometheus/prometheus#18344) - \[FEATURE] Scrape: Added a feature flag `st-synthesis` which synthesizes unknown STs for scraped cumulative metrics. Useful when Remote Writing 2.0 with delta or Otel-based backends. [#18279](prometheus/prometheus#18279) - \[FEATURE] promqltest: support `@st` annotation in `load` blocks to specify per-sample start timestamps. [#18360](prometheus/prometheus#18360) - \[ENHANCEMENT] API: reject concurrent fgprof profiles. [#18651](prometheus/prometheus#18651) - \[ENHANCEMENT] AWS SD: Add optional `external_id` field to ECS/MSK/RDS/Elasticache. [#18579](prometheus/prometheus#18579) - \[ENHANCEMENT] AWS SD: Add optional `external_id` field. [#17171](prometheus/prometheus#17171) - \[ENHANCEMENT] Discovery: Propagate SD target updates faster by introducing dynamic backoff interval instead of static 5s interval for throttling. [#18187](prometheus/prometheus#18187) - \[ENHANCEMENT] Promtool: Add `--header` flag to `query instant` command, matching existing `query range` behaviour. [#18418](prometheus/prometheus#18418) - \[ENHANCEMENT]: AWS SD: Allows EC2 service discovery to discover IPv6 addresses to communicate with target endpoints. The private IPv4 address remains the default when both IPv4 and IPv6 addresses are present. [#16088](prometheus/prometheus#16088) - \[PERF] TSDB: Make head chunk lookup in range queries constant time instead of quadratic time [#18302](prometheus/prometheus#18302) - \[PERF] TSDB: Skip entire stripes in mmapHeadChunks when no series need mmapping, reducing CPU utilization significantly at production-relevant scales. [#18541](prometheus/prometheus#18541) - \[PERF] TSDB: Skip clean series during periodic head chunk mmap using cached head chunk count [#18272](prometheus/prometheus#18272) - \[PERF] PromQL: Address FloatHistogram.KahanAdd performance regression on Go 1.26. [#18568](prometheus/prometheus#18568) - \[BUGFIX] PromQL: Fix `info()` function incorrectly handling negated `__name__` matchers [#17932](prometheus/prometheus#17932) - \[BUGFIX] API: Return duration expressions in `/parse_ast`. [#18624](prometheus/prometheus#18624) - \[BUGFIX] API: correctly document formats accepted for duration query request parameters (step, timeout and lookback delta) in OpenAPI spec [#18305](prometheus/prometheus#18305) - \[BUGFIX] Scrape: AppenderV2 now tracks staleness even when OOO/duplicate series errors happen similar to AppenderV1 [#18567](prometheus/prometheus#18567) - \[BUGFIX] Config: Validate remote\_write queue\_config fields at load time to prevent runtime panic and silent misconfiguration. [#18209](prometheus/prometheus#18209) - \[BUGFIX] Discovery/Consul: Add `health_filter` for Health API filtering, fixing breakage when using Catalog-only fields like `ServiceTags` in `filter`. [#18479](prometheus/prometheus#18479) [#18499](prometheus/prometheus#18499) - \[BUGFIX] OTLP: limit decompressed body size for gzip-encoded OTLP write requests. [#18408](prometheus/prometheus#18408) - \[BUGFIX] PromQL: Fix `smoothed` rate/increase returning zero instead of no result when all data falls strictly after the query range. [#18523](prometheus/prometheus#18523) - \[BUGFIX] PromQL: Fix metric name not being dropped when last\_over\_time or first\_over\_time is applied to subqueries containing name-dropping functions like abs(). [#18409](prometheus/prometheus#18409) - \[BUGFIX] PromQL: Fix missing warning when mixing exponential and custom-bucket histograms in stats queries. [#18660](prometheus/prometheus#18660) - \[BUGFIX] PromQL: Fix parsing of `range()` keyword in duration expressions such as `foo[5m+range()]`. [#18623](prometheus/prometheus#18623) - \[BUGFIX] PromQL: Fix smoothed vector selector returning no results in binary operations when the `@` modifier is used. [#18531](prometheus/prometheus#18531) - \[BUGFIX] PromQL: Reject NaN, infinite, and out-of-range duration expressions instead of silently producing an out-of-range time.Duration. [#18639](prometheus/prometheus#18639) - \[BUGFIX] Scrape: Fix panic when scraping malformed native histograms. [#18414](prometheus/prometheus#18414) - \[BUGFIX] Scrape: fix panic when scraping a target exposing a summary with no quantiles via the protobuf format. [#18382](prometheus/prometheus#18382) - \[BUGFIX] Scrape: fix scrape failure log file occasionally not applied after a configuration reload. [#18421](prometheus/prometheus#18421) - \[BUGFIX] TSDB: Allow retention percentage with new data path. [#18628](prometheus/prometheus#18628) - \[BUGFIX] TSDB: Preserve decimal precision in percentage-based retention [#18374](prometheus/prometheus#18374) - \[BUGFIX] TSDB: fix prometheus\_tsdb\_head\_chunks going negative after WAL replay [#18401](prometheus/prometheus#18401) - \[BUGFIX] TSDB: panic with native histograms during query of overlapping chunks. [#18692](prometheus/prometheus#18692) - \[BUGFIX] Tracing: fix startup failure for insecure OTLP HTTP tracing [#18469](prometheus/prometheus#18469) - \[BUGFIX] UI: Escape label values offered by PromQL autocomplete. [#18658](prometheus/prometheus#18658) - \[BUGFIX] UI: Improve Y-axis tick label precision for graph values over small ranges. [#18682](prometheus/prometheus#18682) - \[BUGFIX] `prometheus_sd_refresh*` and `prometheus_sd_discovered_targets` metrics for specific scrape jobs are deleted when the scrape job is removed. [#17614](prometheus/prometheus#17614) - \[BUGFIX] Remote: fixed validation for received RW2 requests when parsing metadata unit symbols. This fixes a case when request would cause (recovered) handler panic. [#18641](prometheus/prometheus#18641) - \[BUGFIX] TSDB/Agent: fix race in agent appender where concurrent appends for the same label set could produce duplicate in-memory series and duplicate WAL records. [#18292](prometheus/prometheus#18292) - \[BUGFIX] Config: Update `--enable-feature` flag description and sort feature names. [#18487](prometheus/prometheus#18487)

@hibrian827

##### [\`v3.12.0\`](https://github.com/prometheus/prometheus/releases/tag/v3.12.0) This release contains security fixes, new features (especially around PromQL and Service Discovery), performance improvements in TSDB, Start Timestamp improvements and numerous bug fixes. Thanks to all contributors! #### Key Highlights - **Security**: Two security vulnerabilities have been addressed: a denial of service in remote-write (snappy decompression limit) and a secret exposure leak in STACKIT service discovery. - **PromQL & Metadata**: Several features and bug fixes related to the experimental "start timestamps" support, including updates to `rate()`, `irate()`, `increase()`, and `resets()`. New experimental functions `start()`, `end()`, `range()`, and `step()` are introduced. - **TSDB Performance**: Optimizations in head chunk lookup (constant time) and mmap operations to reduce CPU usage. - **Service Discovery**: Added support for DigitalOcean Managed Databases and Outscale VM, along with improvements to AWS SD (IPv6 support for EC2, external ID support). - **UI**: Added a web interface for deleting time series and cleaning tombstones. #### Changelog - \[SECURITY] Remote: Reject snappy-compressed received requests via Remote Write whose declared decoded length exceeds the 32MB. Thanks to [@hibrian827](https://github.com/hibrian827) for reporting it. [#18642](prometheus/prometheus#18642) - \[SECURITY] STACKIT SD: Fix secrets being exposed in plaintext via `/-/config` endpoint. Thanks to [@August829](https://github.com/August829) and [@Phaxma](https://github.com/Phaxma) for reporting. GHSA-39j6-789q-qxvh [#18649](prometheus/prometheus#18649) - \[CHANGE] TSDB/Agent: Adds Start Timestamp field to all WAL Histogram samples in memory; used `st-storage` flag is enabled. [#18221](prometheus/prometheus#18221) - \[FEATURE] API: Add `/api/v1/status/self_metrics` endpoint returning the current state of the Prometheus server's own metrics about itself as JSON. [#18411](prometheus/prometheus#18411) - \[FEATURE] Discovery: Add DigitalOcean Managed Databases service discovery [#18287](prometheus/prometheus#18287) - \[FEATURE] Prometheus: Add support for the aix/ppc64 compilation target [#18321](prometheus/prometheus#18321) - \[FEATURE] Discovery: Add Outscale VM service discovery (`outscale_sd_configs`) for discovering scrape targets from the Outscale Cloud API. [#18139](prometheus/prometheus#18139) - \[FEATURE] PromQL: Emit a warning when `sort`, `sort_by_label` or `sort_by_label_desc` is used within range (matrix) queries, as these functions do not have effect in that context. [#18498](prometheus/prometheus#18498) - \[FEATURE] PromQL: Add `start()`, `end()`, `range()`, and `step()` experimental functions [#17877](prometheus/prometheus#17877) - \[FEATURE] PromQL: Update `resets()` function to consider start timestamp resets. Hidden behind `use-start-timestamps` feature flag. [#18627](prometheus/prometheus#18627) - \[FEATURE] Prometheus: Promote auto-reload-config as stable [#18620](prometheus/prometheus#18620) - \[FEATURE] TSDB/Agent: Add `CheckpointFromInMemorySeries` option to `agent.DB` that enables checkpoint based on in-memory series. [#17948](prometheus/prometheus#17948) - \[FEATURE] UI: Add a web interface for deleting time series and cleaning tombstones, accessible from the Status menu. [#18390](prometheus/prometheus#18390) - \[FEATURE] PromQL: Use start timestamps for `rate()`, `irate()`, and `increase()` calculations, behind a feature flag `use-start-timestamps`. Doesn't work together with extended range selectors `anchored` and `smoothed`. [#18344](prometheus/prometheus#18344) - \[FEATURE] Scrape: Added a feature flag `st-synthesis` which synthesizes unknown STs for scraped cumulative metrics. Useful when Remote Writing 2.0 with delta or Otel-based backends. [#18279](prometheus/prometheus#18279) - \[FEATURE] promqltest: support `@st` annotation in `load` blocks to specify per-sample start timestamps. [#18360](prometheus/prometheus#18360) - \[ENHANCEMENT] API: reject concurrent fgprof profiles. [#18651](prometheus/prometheus#18651) - \[ENHANCEMENT] AWS SD: Add optional `external_id` field to ECS/MSK/RDS/Elasticache. [#18579](prometheus/prometheus#18579) - \[ENHANCEMENT] AWS SD: Add optional `external_id` field. [#17171](prometheus/prometheus#17171) - \[ENHANCEMENT] Discovery: Propagate SD target updates faster by introducing dynamic backoff interval instead of static 5s interval for throttling. [#18187](prometheus/prometheus#18187) - \[ENHANCEMENT] Promtool: Add `--header` flag to `query instant` command, matching existing `query range` behaviour. [#18418](prometheus/prometheus#18418) - \[ENHANCEMENT]: AWS SD: Allows EC2 service discovery to discover IPv6 addresses to communicate with target endpoints. The private IPv4 address remains the default when both IPv4 and IPv6 addresses are present. [#16088](prometheus/prometheus#16088) - \[PERF] TSDB: Make head chunk lookup in range queries constant time instead of quadratic time [#18302](prometheus/prometheus#18302) - \[PERF] TSDB: Skip entire stripes in mmapHeadChunks when no series need mmapping, reducing CPU utilization significantly at production-relevant scales. [#18541](prometheus/prometheus#18541) - \[PERF] TSDB: Skip clean series during periodic head chunk mmap using cached head chunk count [#18272](prometheus/prometheus#18272) - \[PERF] PromQL: Address FloatHistogram.KahanAdd performance regression on Go 1.26. [#18568](prometheus/prometheus#18568) - \[BUGFIX] PromQL: Fix `info()` function incorrectly handling negated `__name__` matchers [#17932](prometheus/prometheus#17932) - \[BUGFIX] API: Return duration expressions in `/parse_ast`. [#18624](prometheus/prometheus#18624) - \[BUGFIX] API: correctly document formats accepted for duration query request parameters (step, timeout and lookback delta) in OpenAPI spec [#18305](prometheus/prometheus#18305) - \[BUGFIX] Scrape: AppenderV2 now tracks staleness even when OOO/duplicate series errors happen similar to AppenderV1 [#18567](prometheus/prometheus#18567) - \[BUGFIX] Config: Validate remote\_write queue\_config fields at load time to prevent runtime panic and silent misconfiguration. [#18209](prometheus/prometheus#18209) - \[BUGFIX] Discovery/Consul: Add `health_filter` for Health API filtering, fixing breakage when using Catalog-only fields like `ServiceTags` in `filter`. [#18479](prometheus/prometheus#18479) [#18499](prometheus/prometheus#18499) - \[BUGFIX] OTLP: limit decompressed body size for gzip-encoded OTLP write requests. [#18408](prometheus/prometheus#18408) - \[BUGFIX] PromQL: Fix `smoothed` rate/increase returning zero instead of no result when all data falls strictly after the query range. [#18523](prometheus/prometheus#18523) - \[BUGFIX] PromQL: Fix metric name not being dropped when last\_over\_time or first\_over\_time is applied to subqueries containing name-dropping functions like abs(). [#18409](prometheus/prometheus#18409) - \[BUGFIX] PromQL: Fix missing warning when mixing exponential and custom-bucket histograms in stats queries. [#18660](prometheus/prometheus#18660) - \[BUGFIX] PromQL: Fix parsing of `range()` keyword in duration expressions such as `foo[5m+range()]`. [#18623](prometheus/prometheus#18623) - \[BUGFIX] PromQL: Fix smoothed vector selector returning no results in binary operations when the `@` modifier is used. [#18531](prometheus/prometheus#18531) - \[BUGFIX] PromQL: Reject NaN, infinite, and out-of-range duration expressions instead of silently producing an out-of-range time.Duration. [#18639](prometheus/prometheus#18639) - \[BUGFIX] Scrape: Fix panic when scraping malformed native histograms. [#18414](prometheus/prometheus#18414) - \[BUGFIX] Scrape: fix panic when scraping a target exposing a summary with no quantiles via the protobuf format. [#18382](prometheus/prometheus#18382) - \[BUGFIX] Scrape: fix scrape failure log file occasionally not applied after a configuration reload. [#18421](prometheus/prometheus#18421) - \[BUGFIX] TSDB: Allow retention percentage with new data path. [#18628](prometheus/prometheus#18628) - \[BUGFIX] TSDB: Preserve decimal precision in percentage-based retention [#18374](prometheus/prometheus#18374) - \[BUGFIX] TSDB: fix prometheus\_tsdb\_head\_chunks going negative after WAL replay [#18401](prometheus/prometheus#18401) - \[BUGFIX] TSDB: panic with native histograms during query of overlapping chunks. [#18692](prometheus/prometheus#18692) - \[BUGFIX] Tracing: fix startup failure for insecure OTLP HTTP tracing [#18469](prometheus/prometheus#18469) - \[BUGFIX] UI: Escape label values offered by PromQL autocomplete. [#18658](prometheus/prometheus#18658) - \[BUGFIX] UI: Improve Y-axis tick label precision for graph values over small ranges. [#18682](prometheus/prometheus#18682) - \[BUGFIX] `prometheus_sd_refresh*` and `prometheus_sd_discovered_targets` metrics for specific scrape jobs are deleted when the scrape job is removed. [#17614](prometheus/prometheus#17614) - \[BUGFIX] Remote: fixed validation for received RW2 requests when parsing metadata unit symbols. This fixes a case when request would cause (recovered) handler panic. [#18641](prometheus/prometheus#18641) - \[BUGFIX] TSDB/Agent: fix race in agent appender where concurrent appends for the same label set could produce duplicate in-memory series and duplicate WAL records. [#18292](prometheus/prometheus#18292) - \[BUGFIX] Config: Update `--enable-feature` flag description and sort feature names. [#18487](prometheus/prometheus#18487)

@hibrian827

##### [\`v3.12.0\`](https://github.com/prometheus/prometheus/releases/tag/v3.12.0) This release contains security fixes, new features (especially around PromQL and Service Discovery), performance improvements in TSDB, Start Timestamp improvements and numerous bug fixes. Thanks to all contributors! #### Key Highlights - **Security**: Two security vulnerabilities have been addressed: a denial of service in remote-write (snappy decompression limit) and a secret exposure leak in STACKIT service discovery. - **PromQL & Metadata**: Several features and bug fixes related to the experimental "start timestamps" support, including updates to `rate()`, `irate()`, `increase()`, and `resets()`. New experimental functions `start()`, `end()`, `range()`, and `step()` are introduced. - **TSDB Performance**: Optimizations in head chunk lookup (constant time) and mmap operations to reduce CPU usage. - **Service Discovery**: Added support for DigitalOcean Managed Databases and Outscale VM, along with improvements to AWS SD (IPv6 support for EC2, external ID support). - **UI**: Added a web interface for deleting time series and cleaning tombstones. #### Changelog - \[SECURITY] Remote: Reject snappy-compressed received requests via Remote Write whose declared decoded length exceeds the 32MB. Thanks to [@hibrian827](https://github.com/hibrian827) for reporting it. [#18642](prometheus/prometheus#18642) - \[SECURITY] STACKIT SD: Fix secrets being exposed in plaintext via `/-/config` endpoint. Thanks to [@August829](https://github.com/August829) and [@Phaxma](https://github.com/Phaxma) for reporting. GHSA-39j6-789q-qxvh [#18649](prometheus/prometheus#18649) - \[CHANGE] TSDB/Agent: Adds Start Timestamp field to all WAL Histogram samples in memory; used `st-storage` flag is enabled. [#18221](prometheus/prometheus#18221) - \[FEATURE] API: Add `/api/v1/status/self_metrics` endpoint returning the current state of the Prometheus server's own metrics about itself as JSON. [#18411](prometheus/prometheus#18411) - \[FEATURE] Discovery: Add DigitalOcean Managed Databases service discovery [#18287](prometheus/prometheus#18287) - \[FEATURE] Prometheus: Add support for the aix/ppc64 compilation target [#18321](prometheus/prometheus#18321) - \[FEATURE] Discovery: Add Outscale VM service discovery (`outscale_sd_configs`) for discovering scrape targets from the Outscale Cloud API. [#18139](prometheus/prometheus#18139) - \[FEATURE] PromQL: Emit a warning when `sort`, `sort_by_label` or `sort_by_label_desc` is used within range (matrix) queries, as these functions do not have effect in that context. [#18498](prometheus/prometheus#18498) - \[FEATURE] PromQL: Add `start()`, `end()`, `range()`, and `step()` experimental functions [#17877](prometheus/prometheus#17877) - \[FEATURE] PromQL: Update `resets()` function to consider start timestamp resets. Hidden behind `use-start-timestamps` feature flag. [#18627](prometheus/prometheus#18627) - \[FEATURE] Prometheus: Promote auto-reload-config as stable [#18620](prometheus/prometheus#18620) - \[FEATURE] TSDB/Agent: Add `CheckpointFromInMemorySeries` option to `agent.DB` that enables checkpoint based on in-memory series. [#17948](prometheus/prometheus#17948) - \[FEATURE] UI: Add a web interface for deleting time series and cleaning tombstones, accessible from the Status menu. [#18390](prometheus/prometheus#18390) - \[FEATURE] PromQL: Use start timestamps for `rate()`, `irate()`, and `increase()` calculations, behind a feature flag `use-start-timestamps`. Doesn't work together with extended range selectors `anchored` and `smoothed`. [#18344](prometheus/prometheus#18344) - \[FEATURE] Scrape: Added a feature flag `st-synthesis` which synthesizes unknown STs for scraped cumulative metrics. Useful when Remote Writing 2.0 with delta or Otel-based backends. [#18279](prometheus/prometheus#18279) - \[FEATURE] promqltest: support `@st` annotation in `load` blocks to specify per-sample start timestamps. [#18360](prometheus/prometheus#18360) - \[ENHANCEMENT] API: reject concurrent fgprof profiles. [#18651](prometheus/prometheus#18651) - \[ENHANCEMENT] AWS SD: Add optional `external_id` field to ECS/MSK/RDS/Elasticache. [#18579](prometheus/prometheus#18579) - \[ENHANCEMENT] AWS SD: Add optional `external_id` field. [#17171](prometheus/prometheus#17171) - \[ENHANCEMENT] Discovery: Propagate SD target updates faster by introducing dynamic backoff interval instead of static 5s interval for throttling. [#18187](prometheus/prometheus#18187) - \[ENHANCEMENT] Promtool: Add `--header` flag to `query instant` command, matching existing `query range` behaviour. [#18418](prometheus/prometheus#18418) - \[ENHANCEMENT]: AWS SD: Allows EC2 service discovery to discover IPv6 addresses to communicate with target endpoints. The private IPv4 address remains the default when both IPv4 and IPv6 addresses are present. [#16088](prometheus/prometheus#16088) - \[PERF] TSDB: Make head chunk lookup in range queries constant time instead of quadratic time [#18302](prometheus/prometheus#18302) - \[PERF] TSDB: Skip entire stripes in mmapHeadChunks when no series need mmapping, reducing CPU utilization significantly at production-relevant scales. [#18541](prometheus/prometheus#18541) - \[PERF] TSDB: Skip clean series during periodic head chunk mmap using cached head chunk count [#18272](prometheus/prometheus#18272) - \[PERF] PromQL: Address FloatHistogram.KahanAdd performance regression on Go 1.26. [#18568](prometheus/prometheus#18568) - \[BUGFIX] PromQL: Fix `info()` function incorrectly handling negated `__name__` matchers [#17932](prometheus/prometheus#17932) - \[BUGFIX] API: Return duration expressions in `/parse_ast`. [#18624](prometheus/prometheus#18624) - \[BUGFIX] API: correctly document formats accepted for duration query request parameters (step, timeout and lookback delta) in OpenAPI spec [#18305](prometheus/prometheus#18305) - \[BUGFIX] Scrape: AppenderV2 now tracks staleness even when OOO/duplicate series errors happen similar to AppenderV1 [#18567](prometheus/prometheus#18567) - \[BUGFIX] Config: Validate remote\_write queue\_config fields at load time to prevent runtime panic and silent misconfiguration. [#18209](prometheus/prometheus#18209) - \[BUGFIX] Discovery/Consul: Add `health_filter` for Health API filtering, fixing breakage when using Catalog-only fields like `ServiceTags` in `filter`. [#18479](prometheus/prometheus#18479) [#18499](prometheus/prometheus#18499) - \[BUGFIX] OTLP: limit decompressed body size for gzip-encoded OTLP write requests. [#18408](prometheus/prometheus#18408) - \[BUGFIX] PromQL: Fix `smoothed` rate/increase returning zero instead of no result when all data falls strictly after the query range. [#18523](prometheus/prometheus#18523) - \[BUGFIX] PromQL: Fix metric name not being dropped when last\_over\_time or first\_over\_time is applied to subqueries containing name-dropping functions like abs(). [#18409](prometheus/prometheus#18409) - \[BUGFIX] PromQL: Fix missing warning when mixing exponential and custom-bucket histograms in stats queries. [#18660](prometheus/prometheus#18660) - \[BUGFIX] PromQL: Fix parsing of `range()` keyword in duration expressions such as `foo[5m+range()]`. [#18623](prometheus/prometheus#18623) - \[BUGFIX] PromQL: Fix smoothed vector selector returning no results in binary operations when the `@` modifier is used. [#18531](prometheus/prometheus#18531) - \[BUGFIX] PromQL: Reject NaN, infinite, and out-of-range duration expressions instead of silently producing an out-of-range time.Duration. [#18639](prometheus/prometheus#18639) - \[BUGFIX] Scrape: Fix panic when scraping malformed native histograms. [#18414](prometheus/prometheus#18414) - \[BUGFIX] Scrape: fix panic when scraping a target exposing a summary with no quantiles via the protobuf format. [#18382](prometheus/prometheus#18382) - \[BUGFIX] Scrape: fix scrape failure log file occasionally not applied after a configuration reload. [#18421](prometheus/prometheus#18421) - \[BUGFIX] TSDB: Allow retention percentage with new data path. [#18628](prometheus/prometheus#18628) - \[BUGFIX] TSDB: Preserve decimal precision in percentage-based retention [#18374](prometheus/prometheus#18374) - \[BUGFIX] TSDB: fix prometheus\_tsdb\_head\_chunks going negative after WAL replay [#18401](prometheus/prometheus#18401) - \[BUGFIX] TSDB: panic with native histograms during query of overlapping chunks. [#18692](prometheus/prometheus#18692) - \[BUGFIX] Tracing: fix startup failure for insecure OTLP HTTP tracing [#18469](prometheus/prometheus#18469) - \[BUGFIX] UI: Escape label values offered by PromQL autocomplete. [#18658](prometheus/prometheus#18658) - \[BUGFIX] UI: Improve Y-axis tick label precision for graph values over small ranges. [#18682](prometheus/prometheus#18682) - \[BUGFIX] `prometheus_sd_refresh*` and `prometheus_sd_discovered_targets` metrics for specific scrape jobs are deleted when the scrape job is removed. [#17614](prometheus/prometheus#17614) - \[BUGFIX] Remote: fixed validation for received RW2 requests when parsing metadata unit symbols. This fixes a case when request would cause (recovered) handler panic. [#18641](prometheus/prometheus#18641) - \[BUGFIX] TSDB/Agent: fix race in agent appender where concurrent appends for the same label set could produce duplicate in-memory series and duplicate WAL records. [#18292](prometheus/prometheus#18292) - \[BUGFIX] Config: Update `--enable-feature` flag description and sort feature names. [#18487](prometheus/prometheus#18487)

@hibrian827

##### [\`v3.12.0\`](https://github.com/prometheus/prometheus/releases/tag/v3.12.0) This release contains security fixes, new features (especially around PromQL and Service Discovery), performance improvements in TSDB, Start Timestamp improvements and numerous bug fixes. Thanks to all contributors! #### Key Highlights - **Security**: Two security vulnerabilities have been addressed: a denial of service in remote-write (snappy decompression limit) and a secret exposure leak in STACKIT service discovery. - **PromQL & Metadata**: Several features and bug fixes related to the experimental "start timestamps" support, including updates to `rate()`, `irate()`, `increase()`, and `resets()`. New experimental functions `start()`, `end()`, `range()`, and `step()` are introduced. - **TSDB Performance**: Optimizations in head chunk lookup (constant time) and mmap operations to reduce CPU usage. - **Service Discovery**: Added support for DigitalOcean Managed Databases and Outscale VM, along with improvements to AWS SD (IPv6 support for EC2, external ID support). - **UI**: Added a web interface for deleting time series and cleaning tombstones. #### Changelog - \[SECURITY] Remote: Reject snappy-compressed received requests via Remote Write whose declared decoded length exceeds the 32MB. Thanks to [@hibrian827](https://github.com/hibrian827) for reporting it. [#18642](prometheus/prometheus#18642) - \[SECURITY] STACKIT SD: Fix secrets being exposed in plaintext via `/-/config` endpoint. Thanks to [@August829](https://github.com/August829) and [@Phaxma](https://github.com/Phaxma) for reporting. GHSA-39j6-789q-qxvh [#18649](prometheus/prometheus#18649) - \[CHANGE] TSDB/Agent: Adds Start Timestamp field to all WAL Histogram samples in memory; used `st-storage` flag is enabled. [#18221](prometheus/prometheus#18221) - \[FEATURE] API: Add `/api/v1/status/self_metrics` endpoint returning the current state of the Prometheus server's own metrics about itself as JSON. [#18411](prometheus/prometheus#18411) - \[FEATURE] Discovery: Add DigitalOcean Managed Databases service discovery [#18287](prometheus/prometheus#18287) - \[FEATURE] Prometheus: Add support for the aix/ppc64 compilation target [#18321](prometheus/prometheus#18321) - \[FEATURE] Discovery: Add Outscale VM service discovery (`outscale_sd_configs`) for discovering scrape targets from the Outscale Cloud API. [#18139](prometheus/prometheus#18139) - \[FEATURE] PromQL: Emit a warning when `sort`, `sort_by_label` or `sort_by_label_desc` is used within range (matrix) queries, as these functions do not have effect in that context. [#18498](prometheus/prometheus#18498) - \[FEATURE] PromQL: Add `start()`, `end()`, `range()`, and `step()` experimental functions [#17877](prometheus/prometheus#17877) - \[FEATURE] PromQL: Update `resets()` function to consider start timestamp resets. Hidden behind `use-start-timestamps` feature flag. [#18627](prometheus/prometheus#18627) - \[FEATURE] Prometheus: Promote auto-reload-config as stable [#18620](prometheus/prometheus#18620) - \[FEATURE] TSDB/Agent: Add `CheckpointFromInMemorySeries` option to `agent.DB` that enables checkpoint based on in-memory series. [#17948](prometheus/prometheus#17948) - \[FEATURE] UI: Add a web interface for deleting time series and cleaning tombstones, accessible from the Status menu. [#18390](prometheus/prometheus#18390) - \[FEATURE] PromQL: Use start timestamps for `rate()`, `irate()`, and `increase()` calculations, behind a feature flag `use-start-timestamps`. Doesn't work together with extended range selectors `anchored` and `smoothed`. [#18344](prometheus/prometheus#18344) - \[FEATURE] Scrape: Added a feature flag `st-synthesis` which synthesizes unknown STs for scraped cumulative metrics. Useful when Remote Writing 2.0 with delta or Otel-based backends. [#18279](prometheus/prometheus#18279) - \[FEATURE] promqltest: support `@st` annotation in `load` blocks to specify per-sample start timestamps. [#18360](prometheus/prometheus#18360) - \[ENHANCEMENT] API: reject concurrent fgprof profiles. [#18651](prometheus/prometheus#18651) - \[ENHANCEMENT] AWS SD: Add optional `external_id` field to ECS/MSK/RDS/Elasticache. [#18579](prometheus/prometheus#18579) - \[ENHANCEMENT] AWS SD: Add optional `external_id` field. [#17171](prometheus/prometheus#17171) - \[ENHANCEMENT] Discovery: Propagate SD target updates faster by introducing dynamic backoff interval instead of static 5s interval for throttling. [#18187](prometheus/prometheus#18187) - \[ENHANCEMENT] Promtool: Add `--header` flag to `query instant` command, matching existing `query range` behaviour. [#18418](prometheus/prometheus#18418) - \[ENHANCEMENT]: AWS SD: Allows EC2 service discovery to discover IPv6 addresses to communicate with target endpoints. The private IPv4 address remains the default when both IPv4 and IPv6 addresses are present. [#16088](prometheus/prometheus#16088) - \[PERF] TSDB: Make head chunk lookup in range queries constant time instead of quadratic time [#18302](prometheus/prometheus#18302) - \[PERF] TSDB: Skip entire stripes in mmapHeadChunks when no series need mmapping, reducing CPU utilization significantly at production-relevant scales. [#18541](prometheus/prometheus#18541) - \[PERF] TSDB: Skip clean series during periodic head chunk mmap using cached head chunk count [#18272](prometheus/prometheus#18272) - \[PERF] PromQL: Address FloatHistogram.KahanAdd performance regression on Go 1.26. [#18568](prometheus/prometheus#18568) - \[BUGFIX] PromQL: Fix `info()` function incorrectly handling negated `__name__` matchers [#17932](prometheus/prometheus#17932) - \[BUGFIX] API: Return duration expressions in `/parse_ast`. [#18624](prometheus/prometheus#18624) - \[BUGFIX] API: correctly document formats accepted for duration query request parameters (step, timeout and lookback delta) in OpenAPI spec [#18305](prometheus/prometheus#18305) - \[BUGFIX] Scrape: AppenderV2 now tracks staleness even when OOO/duplicate series errors happen similar to AppenderV1 [#18567](prometheus/prometheus#18567) - \[BUGFIX] Config: Validate remote\_write queue\_config fields at load time to prevent runtime panic and silent misconfiguration. [#18209](prometheus/prometheus#18209) - \[BUGFIX] Discovery/Consul: Add `health_filter` for Health API filtering, fixing breakage when using Catalog-only fields like `ServiceTags` in `filter`. [#18479](prometheus/prometheus#18479) [#18499](prometheus/prometheus#18499) - \[BUGFIX] OTLP: limit decompressed body size for gzip-encoded OTLP write requests. [#18408](prometheus/prometheus#18408) - \[BUGFIX] PromQL: Fix `smoothed` rate/increase returning zero instead of no result when all data falls strictly after the query range. [#18523](prometheus/prometheus#18523) - \[BUGFIX] PromQL: Fix metric name not being dropped when last\_over\_time or first\_over\_time is applied to subqueries containing name-dropping functions like abs(). [#18409](prometheus/prometheus#18409) - \[BUGFIX] PromQL: Fix missing warning when mixing exponential and custom-bucket histograms in stats queries. [#18660](prometheus/prometheus#18660) - \[BUGFIX] PromQL: Fix parsing of `range()` keyword in duration expressions such as `foo[5m+range()]`. [#18623](prometheus/prometheus#18623) - \[BUGFIX] PromQL: Fix smoothed vector selector returning no results in binary operations when the `@` modifier is used. [#18531](prometheus/prometheus#18531) - \[BUGFIX] PromQL: Reject NaN, infinite, and out-of-range duration expressions instead of silently producing an out-of-range time.Duration. [#18639](prometheus/prometheus#18639) - \[BUGFIX] Scrape: Fix panic when scraping malformed native histograms. [#18414](prometheus/prometheus#18414) - \[BUGFIX] Scrape: fix panic when scraping a target exposing a summary with no quantiles via the protobuf format. [#18382](prometheus/prometheus#18382) - \[BUGFIX] Scrape: fix scrape failure log file occasionally not applied after a configuration reload. [#18421](prometheus/prometheus#18421) - \[BUGFIX] TSDB: Allow retention percentage with new data path. [#18628](prometheus/prometheus#18628) - \[BUGFIX] TSDB: Preserve decimal precision in percentage-based retention [#18374](prometheus/prometheus#18374) - \[BUGFIX] TSDB: fix prometheus\_tsdb\_head\_chunks going negative after WAL replay [#18401](prometheus/prometheus#18401) - \[BUGFIX] TSDB: panic with native histograms during query of overlapping chunks. [#18692](prometheus/prometheus#18692) - \[BUGFIX] Tracing: fix startup failure for insecure OTLP HTTP tracing [#18469](prometheus/prometheus#18469) - \[BUGFIX] UI: Escape label values offered by PromQL autocomplete. [#18658](prometheus/prometheus#18658) - \[BUGFIX] UI: Improve Y-axis tick label precision for graph values over small ranges. [#18682](prometheus/prometheus#18682) - \[BUGFIX] `prometheus_sd_refresh*` and `prometheus_sd_discovered_targets` metrics for specific scrape jobs are deleted when the scrape job is removed. [#17614](prometheus/prometheus#17614) - \[BUGFIX] Remote: fixed validation for received RW2 requests when parsing metadata unit symbols. This fixes a case when request would cause (recovered) handler panic. [#18641](prometheus/prometheus#18641) - \[BUGFIX] TSDB/Agent: fix race in agent appender where concurrent appends for the same label set could produce duplicate in-memory series and duplicate WAL records. [#18292](prometheus/prometheus#18292) - \[BUGFIX] Config: Update `--enable-feature` flag description and sort feature names. [#18487](prometheus/prometheus#18487)

@hibrian827

##### [\`v3.12.0\`](https://github.com/prometheus/prometheus/releases/tag/v3.12.0) This release contains security fixes, new features (especially around PromQL and Service Discovery), performance improvements in TSDB, Start Timestamp improvements and numerous bug fixes. Thanks to all contributors! #### Key Highlights - **Security**: Two security vulnerabilities have been addressed: a denial of service in remote-write (snappy decompression limit) and a secret exposure leak in STACKIT service discovery. - **PromQL & Metadata**: Several features and bug fixes related to the experimental "start timestamps" support, including updates to `rate()`, `irate()`, `increase()`, and `resets()`. New experimental functions `start()`, `end()`, `range()`, and `step()` are introduced. - **TSDB Performance**: Optimizations in head chunk lookup (constant time) and mmap operations to reduce CPU usage. - **Service Discovery**: Added support for DigitalOcean Managed Databases and Outscale VM, along with improvements to AWS SD (IPv6 support for EC2, external ID support). - **UI**: Added a web interface for deleting time series and cleaning tombstones. #### Changelog - \[SECURITY] Remote: Reject snappy-compressed received requests via Remote Write whose declared decoded length exceeds the 32MB. Thanks to [@hibrian827](https://github.com/hibrian827) for reporting it. [#18642](prometheus/prometheus#18642) - \[SECURITY] STACKIT SD: Fix secrets being exposed in plaintext via `/-/config` endpoint. Thanks to [@August829](https://github.com/August829) and [@Phaxma](https://github.com/Phaxma) for reporting. GHSA-39j6-789q-qxvh [#18649](prometheus/prometheus#18649) - \[CHANGE] TSDB/Agent: Adds Start Timestamp field to all WAL Histogram samples in memory; used `st-storage` flag is enabled. [#18221](prometheus/prometheus#18221) - \[FEATURE] API: Add `/api/v1/status/self_metrics` endpoint returning the current state of the Prometheus server's own metrics about itself as JSON. [#18411](prometheus/prometheus#18411) - \[FEATURE] Discovery: Add DigitalOcean Managed Databases service discovery [#18287](prometheus/prometheus#18287) - \[FEATURE] Prometheus: Add support for the aix/ppc64 compilation target [#18321](prometheus/prometheus#18321) - \[FEATURE] Discovery: Add Outscale VM service discovery (`outscale_sd_configs`) for discovering scrape targets from the Outscale Cloud API. [#18139](prometheus/prometheus#18139) - \[FEATURE] PromQL: Emit a warning when `sort`, `sort_by_label` or `sort_by_label_desc` is used within range (matrix) queries, as these functions do not have effect in that context. [#18498](prometheus/prometheus#18498) - \[FEATURE] PromQL: Add `start()`, `end()`, `range()`, and `step()` experimental functions [#17877](prometheus/prometheus#17877) - \[FEATURE] PromQL: Update `resets()` function to consider start timestamp resets. Hidden behind `use-start-timestamps` feature flag. [#18627](prometheus/prometheus#18627) - \[FEATURE] Prometheus: Promote auto-reload-config as stable [#18620](prometheus/prometheus#18620) - \[FEATURE] TSDB/Agent: Add `CheckpointFromInMemorySeries` option to `agent.DB` that enables checkpoint based on in-memory series. [#17948](prometheus/prometheus#17948) - \[FEATURE] UI: Add a web interface for deleting time series and cleaning tombstones, accessible from the Status menu. [#18390](prometheus/prometheus#18390) - \[FEATURE] PromQL: Use start timestamps for `rate()`, `irate()`, and `increase()` calculations, behind a feature flag `use-start-timestamps`. Doesn't work together with extended range selectors `anchored` and `smoothed`. [#18344](prometheus/prometheus#18344) - \[FEATURE] Scrape: Added a feature flag `st-synthesis` which synthesizes unknown STs for scraped cumulative metrics. Useful when Remote Writing 2.0 with delta or Otel-based backends. [#18279](prometheus/prometheus#18279) - \[FEATURE] promqltest: support `@st` annotation in `load` blocks to specify per-sample start timestamps. [#18360](prometheus/prometheus#18360) - \[ENHANCEMENT] API: reject concurrent fgprof profiles. [#18651](prometheus/prometheus#18651) - \[ENHANCEMENT] AWS SD: Add optional `external_id` field to ECS/MSK/RDS/Elasticache. [#18579](prometheus/prometheus#18579) - \[ENHANCEMENT] AWS SD: Add optional `external_id` field. [#17171](prometheus/prometheus#17171) - \[ENHANCEMENT] Discovery: Propagate SD target updates faster by introducing dynamic backoff interval instead of static 5s interval for throttling. [#18187](prometheus/prometheus#18187) - \[ENHANCEMENT] Promtool: Add `--header` flag to `query instant` command, matching existing `query range` behaviour. [#18418](prometheus/prometheus#18418) - \[ENHANCEMENT]: AWS SD: Allows EC2 service discovery to discover IPv6 addresses to communicate with target endpoints. The private IPv4 address remains the default when both IPv4 and IPv6 addresses are present. [#16088](prometheus/prometheus#16088) - \[PERF] TSDB: Make head chunk lookup in range queries constant time instead of quadratic time [#18302](prometheus/prometheus#18302) - \[PERF] TSDB: Skip entire stripes in mmapHeadChunks when no series need mmapping, reducing CPU utilization significantly at production-relevant scales. [#18541](prometheus/prometheus#18541) - \[PERF] TSDB: Skip clean series during periodic head chunk mmap using cached head chunk count [#18272](prometheus/prometheus#18272) - \[PERF] PromQL: Address FloatHistogram.KahanAdd performance regression on Go 1.26. [#18568](prometheus/prometheus#18568) - \[BUGFIX] PromQL: Fix `info()` function incorrectly handling negated `__name__` matchers [#17932](prometheus/prometheus#17932) - \[BUGFIX] API: Return duration expressions in `/parse_ast`. [#18624](prometheus/prometheus#18624) - \[BUGFIX] API: correctly document formats accepted for duration query request parameters (step, timeout and lookback delta) in OpenAPI spec [#18305](prometheus/prometheus#18305) - \[BUGFIX] Scrape: AppenderV2 now tracks staleness even when OOO/duplicate series errors happen similar to AppenderV1 [#18567](prometheus/prometheus#18567) - \[BUGFIX] Config: Validate remote\_write queue\_config fields at load time to prevent runtime panic and silent misconfiguration. [#18209](prometheus/prometheus#18209) - \[BUGFIX] Discovery/Consul: Add `health_filter` for Health API filtering, fixing breakage when using Catalog-only fields like `ServiceTags` in `filter`. [#18479](prometheus/prometheus#18479) [#18499](prometheus/prometheus#18499) - \[BUGFIX] OTLP: limit decompressed body size for gzip-encoded OTLP write requests. [#18408](prometheus/prometheus#18408) - \[BUGFIX] PromQL: Fix `smoothed` rate/increase returning zero instead of no result when all data falls strictly after the query range. [#18523](prometheus/prometheus#18523) - \[BUGFIX] PromQL: Fix metric name not being dropped when last\_over\_time or first\_over\_time is applied to subqueries containing name-dropping functions like abs(). [#18409](prometheus/prometheus#18409) - \[BUGFIX] PromQL: Fix missing warning when mixing exponential and custom-bucket histograms in stats queries. [#18660](prometheus/prometheus#18660) - \[BUGFIX] PromQL: Fix parsing of `range()` keyword in duration expressions such as `foo[5m+range()]`. [#18623](prometheus/prometheus#18623) - \[BUGFIX] PromQL: Fix smoothed vector selector returning no results in binary operations when the `@` modifier is used. [#18531](prometheus/prometheus#18531) - \[BUGFIX] PromQL: Reject NaN, infinite, and out-of-range duration expressions instead of silently producing an out-of-range time.Duration. [#18639](prometheus/prometheus#18639) - \[BUGFIX] Scrape: Fix panic when scraping malformed native histograms. [#18414](prometheus/prometheus#18414) - \[BUGFIX] Scrape: fix panic when scraping a target exposing a summary with no quantiles via the protobuf format. [#18382](prometheus/prometheus#18382) - \[BUGFIX] Scrape: fix scrape failure log file occasionally not applied after a configuration reload. [#18421](prometheus/prometheus#18421) - \[BUGFIX] TSDB: Allow retention percentage with new data path. [#18628](prometheus/prometheus#18628) - \[BUGFIX] TSDB: Preserve decimal precision in percentage-based retention [#18374](prometheus/prometheus#18374) - \[BUGFIX] TSDB: fix prometheus\_tsdb\_head\_chunks going negative after WAL replay [#18401](prometheus/prometheus#18401) - \[BUGFIX] TSDB: panic with native histograms during query of overlapping chunks. [#18692](prometheus/prometheus#18692) - \[BUGFIX] Tracing: fix startup failure for insecure OTLP HTTP tracing [#18469](prometheus/prometheus#18469) - \[BUGFIX] UI: Escape label values offered by PromQL autocomplete. [#18658](prometheus/prometheus#18658) - \[BUGFIX] UI: Improve Y-axis tick label precision for graph values over small ranges. [#18682](prometheus/prometheus#18682) - \[BUGFIX] `prometheus_sd_refresh*` and `prometheus_sd_discovered_targets` metrics for specific scrape jobs are deleted when the scrape job is removed. [#17614](prometheus/prometheus#17614) - \[BUGFIX] Remote: fixed validation for received RW2 requests when parsing metadata unit symbols. This fixes a case when request would cause (recovered) handler panic. [#18641](prometheus/prometheus#18641) - \[BUGFIX] TSDB/Agent: fix race in agent appender where concurrent appends for the same label set could produce duplicate in-memory series and duplicate WAL records. [#18292](prometheus/prometheus#18292) - \[BUGFIX] Config: Update `--enable-feature` flag description and sort feature names. [#18487](prometheus/prometheus#18487)

@hibrian827

##### [\`v3.12.0\`](https://github.com/prometheus/prometheus/releases/tag/v3.12.0) This release contains security fixes, new features (especially around PromQL and Service Discovery), performance improvements in TSDB, Start Timestamp improvements and numerous bug fixes. Thanks to all contributors! #### Key Highlights - **Security**: Two security vulnerabilities have been addressed: a denial of service in remote-write (snappy decompression limit) and a secret exposure leak in STACKIT service discovery. - **PromQL & Metadata**: Several features and bug fixes related to the experimental "start timestamps" support, including updates to `rate()`, `irate()`, `increase()`, and `resets()`. New experimental functions `start()`, `end()`, `range()`, and `step()` are introduced. - **TSDB Performance**: Optimizations in head chunk lookup (constant time) and mmap operations to reduce CPU usage. - **Service Discovery**: Added support for DigitalOcean Managed Databases and Outscale VM, along with improvements to AWS SD (IPv6 support for EC2, external ID support). - **UI**: Added a web interface for deleting time series and cleaning tombstones. #### Changelog - \[SECURITY] Remote: Reject snappy-compressed received requests via Remote Write whose declared decoded length exceeds the 32MB. Thanks to [@hibrian827](https://github.com/hibrian827) for reporting it. [#18642](prometheus/prometheus#18642) - \[SECURITY] STACKIT SD: Fix secrets being exposed in plaintext via `/-/config` endpoint. Thanks to [@August829](https://github.com/August829) and [@Phaxma](https://github.com/Phaxma) for reporting. GHSA-39j6-789q-qxvh [#18649](prometheus/prometheus#18649) - \[CHANGE] TSDB/Agent: Adds Start Timestamp field to all WAL Histogram samples in memory; used `st-storage` flag is enabled. [#18221](prometheus/prometheus#18221) - \[FEATURE] API: Add `/api/v1/status/self_metrics` endpoint returning the current state of the Prometheus server's own metrics about itself as JSON. [#18411](prometheus/prometheus#18411) - \[FEATURE] Discovery: Add DigitalOcean Managed Databases service discovery [#18287](prometheus/prometheus#18287) - \[FEATURE] Prometheus: Add support for the aix/ppc64 compilation target [#18321](prometheus/prometheus#18321) - \[FEATURE] Discovery: Add Outscale VM service discovery (`outscale_sd_configs`) for discovering scrape targets from the Outscale Cloud API. [#18139](prometheus/prometheus#18139) - \[FEATURE] PromQL: Emit a warning when `sort`, `sort_by_label` or `sort_by_label_desc` is used within range (matrix) queries, as these functions do not have effect in that context. [#18498](prometheus/prometheus#18498) - \[FEATURE] PromQL: Add `start()`, `end()`, `range()`, and `step()` experimental functions [#17877](prometheus/prometheus#17877) - \[FEATURE] PromQL: Update `resets()` function to consider start timestamp resets. Hidden behind `use-start-timestamps` feature flag. [#18627](prometheus/prometheus#18627) - \[FEATURE] Prometheus: Promote auto-reload-config as stable [#18620](prometheus/prometheus#18620) - \[FEATURE] TSDB/Agent: Add `CheckpointFromInMemorySeries` option to `agent.DB` that enables checkpoint based on in-memory series. [#17948](prometheus/prometheus#17948) - \[FEATURE] UI: Add a web interface for deleting time series and cleaning tombstones, accessible from the Status menu. [#18390](prometheus/prometheus#18390) - \[FEATURE] PromQL: Use start timestamps for `rate()`, `irate()`, and `increase()` calculations, behind a feature flag `use-start-timestamps`. Doesn't work together with extended range selectors `anchored` and `smoothed`. [#18344](prometheus/prometheus#18344) - \[FEATURE] Scrape: Added a feature flag `st-synthesis` which synthesizes unknown STs for scraped cumulative metrics. Useful when Remote Writing 2.0 with delta or Otel-based backends. [#18279](prometheus/prometheus#18279) - \[FEATURE] promqltest: support `@st` annotation in `load` blocks to specify per-sample start timestamps. [#18360](prometheus/prometheus#18360) - \[ENHANCEMENT] API: reject concurrent fgprof profiles. [#18651](prometheus/prometheus#18651) - \[ENHANCEMENT] AWS SD: Add optional `external_id` field to ECS/MSK/RDS/Elasticache. [#18579](prometheus/prometheus#18579) - \[ENHANCEMENT] AWS SD: Add optional `external_id` field. [#17171](prometheus/prometheus#17171) - \[ENHANCEMENT] Discovery: Propagate SD target updates faster by introducing dynamic backoff interval instead of static 5s interval for throttling. [#18187](prometheus/prometheus#18187) - \[ENHANCEMENT] Promtool: Add `--header` flag to `query instant` command, matching existing `query range` behaviour. [#18418](prometheus/prometheus#18418) - \[ENHANCEMENT]: AWS SD: Allows EC2 service discovery to discover IPv6 addresses to communicate with target endpoints. The private IPv4 address remains the default when both IPv4 and IPv6 addresses are present. [#16088](prometheus/prometheus#16088) - \[PERF] TSDB: Make head chunk lookup in range queries constant time instead of quadratic time [#18302](prometheus/prometheus#18302) - \[PERF] TSDB: Skip entire stripes in mmapHeadChunks when no series need mmapping, reducing CPU utilization significantly at production-relevant scales. [#18541](prometheus/prometheus#18541) - \[PERF] TSDB: Skip clean series during periodic head chunk mmap using cached head chunk count [#18272](prometheus/prometheus#18272) - \[PERF] PromQL: Address FloatHistogram.KahanAdd performance regression on Go 1.26. [#18568](prometheus/prometheus#18568) - \[BUGFIX] PromQL: Fix `info()` function incorrectly handling negated `__name__` matchers [#17932](prometheus/prometheus#17932) - \[BUGFIX] API: Return duration expressions in `/parse_ast`. [#18624](prometheus/prometheus#18624) - \[BUGFIX] API: correctly document formats accepted for duration query request parameters (step, timeout and lookback delta) in OpenAPI spec [#18305](prometheus/prometheus#18305) - \[BUGFIX] Scrape: AppenderV2 now tracks staleness even when OOO/duplicate series errors happen similar to AppenderV1 [#18567](prometheus/prometheus#18567) - \[BUGFIX] Config: Validate remote\_write queue\_config fields at load time to prevent runtime panic and silent misconfiguration. [#18209](prometheus/prometheus#18209) - \[BUGFIX] Discovery/Consul: Add `health_filter` for Health API filtering, fixing breakage when using Catalog-only fields like `ServiceTags` in `filter`. [#18479](prometheus/prometheus#18479) [#18499](prometheus/prometheus#18499) - \[BUGFIX] OTLP: limit decompressed body size for gzip-encoded OTLP write requests. [#18408](prometheus/prometheus#18408) - \[BUGFIX] PromQL: Fix `smoothed` rate/increase returning zero instead of no result when all data falls strictly after the query range. [#18523](prometheus/prometheus#18523) - \[BUGFIX] PromQL: Fix metric name not being dropped when last\_over\_time or first\_over\_time is applied to subqueries containing name-dropping functions like abs(). [#18409](prometheus/prometheus#18409) - \[BUGFIX] PromQL: Fix missing warning when mixing exponential and custom-bucket histograms in stats queries. [#18660](prometheus/prometheus#18660) - \[BUGFIX] PromQL: Fix parsing of `range()` keyword in duration expressions such as `foo[5m+range()]`. [#18623](prometheus/prometheus#18623) - \[BUGFIX] PromQL: Fix smoothed vector selector returning no results in binary operations when the `@` modifier is used. [#18531](prometheus/prometheus#18531) - \[BUGFIX] PromQL: Reject NaN, infinite, and out-of-range duration expressions instead of silently producing an out-of-range time.Duration. [#18639](prometheus/prometheus#18639) - \[BUGFIX] Scrape: Fix panic when scraping malformed native histograms. [#18414](prometheus/prometheus#18414) - \[BUGFIX] Scrape: fix panic when scraping a target exposing a summary with no quantiles via the protobuf format. [#18382](prometheus/prometheus#18382) - \[BUGFIX] Scrape: fix scrape failure log file occasionally not applied after a configuration reload. [#18421](prometheus/prometheus#18421) - \[BUGFIX] TSDB: Allow retention percentage with new data path. [#18628](prometheus/prometheus#18628) - \[BUGFIX] TSDB: Preserve decimal precision in percentage-based retention [#18374](prometheus/prometheus#18374) - \[BUGFIX] TSDB: fix prometheus\_tsdb\_head\_chunks going negative after WAL replay [#18401](prometheus/prometheus#18401) - \[BUGFIX] TSDB: panic with native histograms during query of overlapping chunks. [#18692](prometheus/prometheus#18692) - \[BUGFIX] Tracing: fix startup failure for insecure OTLP HTTP tracing [#18469](prometheus/prometheus#18469) - \[BUGFIX] UI: Escape label values offered by PromQL autocomplete. [#18658](prometheus/prometheus#18658) - \[BUGFIX] UI: Improve Y-axis tick label precision for graph values over small ranges. [#18682](prometheus/prometheus#18682) - \[BUGFIX] `prometheus_sd_refresh*` and `prometheus_sd_discovered_targets` metrics for specific scrape jobs are deleted when the scrape job is removed. [#17614](prometheus/prometheus#17614) - \[BUGFIX] Remote: fixed validation for received RW2 requests when parsing metadata unit symbols. This fixes a case when request would cause (recovered) handler panic. [#18641](prometheus/prometheus#18641) - \[BUGFIX] TSDB/Agent: fix race in agent appender where concurrent appends for the same label set could produce duplicate in-memory series and duplicate WAL records. [#18292](prometheus/prometheus#18292) - \[BUGFIX] Config: Update `--enable-feature` flag description and sort feature names. [#18487](prometheus/prometheus#18487)

@hibrian827

##### [\`v3.12.0\`](https://github.com/prometheus/prometheus/releases/tag/v3.12.0) This release contains security fixes, new features (especially around PromQL and Service Discovery), performance improvements in TSDB, Start Timestamp improvements and numerous bug fixes. Thanks to all contributors! #### Key Highlights - **Security**: Two security vulnerabilities have been addressed: a denial of service in remote-write (snappy decompression limit) and a secret exposure leak in STACKIT service discovery. - **PromQL & Metadata**: Several features and bug fixes related to the experimental "start timestamps" support, including updates to `rate()`, `irate()`, `increase()`, and `resets()`. New experimental functions `start()`, `end()`, `range()`, and `step()` are introduced. - **TSDB Performance**: Optimizations in head chunk lookup (constant time) and mmap operations to reduce CPU usage. - **Service Discovery**: Added support for DigitalOcean Managed Databases and Outscale VM, along with improvements to AWS SD (IPv6 support for EC2, external ID support). - **UI**: Added a web interface for deleting time series and cleaning tombstones. #### Changelog - \[SECURITY] Remote: Reject snappy-compressed received requests via Remote Write whose declared decoded length exceeds the 32MB. Thanks to [@hibrian827](https://github.com/hibrian827) for reporting it. [#18642](prometheus/prometheus#18642) - \[SECURITY] STACKIT SD: Fix secrets being exposed in plaintext via `/-/config` endpoint. Thanks to [@August829](https://github.com/August829) and [@Phaxma](https://github.com/Phaxma) for reporting. GHSA-39j6-789q-qxvh [#18649](prometheus/prometheus#18649) - \[CHANGE] TSDB/Agent: Adds Start Timestamp field to all WAL Histogram samples in memory; used `st-storage` flag is enabled. [#18221](prometheus/prometheus#18221) - \[FEATURE] API: Add `/api/v1/status/self_metrics` endpoint returning the current state of the Prometheus server's own metrics about itself as JSON. [#18411](prometheus/prometheus#18411) - \[FEATURE] Discovery: Add DigitalOcean Managed Databases service discovery [#18287](prometheus/prometheus#18287) - \[FEATURE] Prometheus: Add support for the aix/ppc64 compilation target [#18321](prometheus/prometheus#18321) - \[FEATURE] Discovery: Add Outscale VM service discovery (`outscale_sd_configs`) for discovering scrape targets from the Outscale Cloud API. [#18139](prometheus/prometheus#18139) - \[FEATURE] PromQL: Emit a warning when `sort`, `sort_by_label` or `sort_by_label_desc` is used within range (matrix) queries, as these functions do not have effect in that context. [#18498](prometheus/prometheus#18498) - \[FEATURE] PromQL: Add `start()`, `end()`, `range()`, and `step()` experimental functions [#17877](prometheus/prometheus#17877) - \[FEATURE] PromQL: Update `resets()` function to consider start timestamp resets. Hidden behind `use-start-timestamps` feature flag. [#18627](prometheus/prometheus#18627) - \[FEATURE] Prometheus: Promote auto-reload-config as stable [#18620](prometheus/prometheus#18620) - \[FEATURE] TSDB/Agent: Add `CheckpointFromInMemorySeries` option to `agent.DB` that enables checkpoint based on in-memory series. [#17948](prometheus/prometheus#17948) - \[FEATURE] UI: Add a web interface for deleting time series and cleaning tombstones, accessible from the Status menu. [#18390](prometheus/prometheus#18390) - \[FEATURE] PromQL: Use start timestamps for `rate()`, `irate()`, and `increase()` calculations, behind a feature flag `use-start-timestamps`. Doesn't work together with extended range selectors `anchored` and `smoothed`. [#18344](prometheus/prometheus#18344) - \[FEATURE] Scrape: Added a feature flag `st-synthesis` which synthesizes unknown STs for scraped cumulative metrics. Useful when Remote Writing 2.0 with delta or Otel-based backends. [#18279](prometheus/prometheus#18279) - \[FEATURE] promqltest: support `@st` annotation in `load` blocks to specify per-sample start timestamps. [#18360](prometheus/prometheus#18360) - \[ENHANCEMENT] API: reject concurrent fgprof profiles. [#18651](prometheus/prometheus#18651) - \[ENHANCEMENT] AWS SD: Add optional `external_id` field to ECS/MSK/RDS/Elasticache. [#18579](prometheus/prometheus#18579) - \[ENHANCEMENT] AWS SD: Add optional `external_id` field. [#17171](prometheus/prometheus#17171) - \[ENHANCEMENT] Discovery: Propagate SD target updates faster by introducing dynamic backoff interval instead of static 5s interval for throttling. [#18187](prometheus/prometheus#18187) - \[ENHANCEMENT] Promtool: Add `--header` flag to `query instant` command, matching existing `query range` behaviour. [#18418](prometheus/prometheus#18418) - \[ENHANCEMENT]: AWS SD: Allows EC2 service discovery to discover IPv6 addresses to communicate with target endpoints. The private IPv4 address remains the default when both IPv4 and IPv6 addresses are present. [#16088](prometheus/prometheus#16088) - \[PERF] TSDB: Make head chunk lookup in range queries constant time instead of quadratic time [#18302](prometheus/prometheus#18302) - \[PERF] TSDB: Skip entire stripes in mmapHeadChunks when no series need mmapping, reducing CPU utilization significantly at production-relevant scales. [#18541](prometheus/prometheus#18541) - \[PERF] TSDB: Skip clean series during periodic head chunk mmap using cached head chunk count [#18272](prometheus/prometheus#18272) - \[PERF] PromQL: Address FloatHistogram.KahanAdd performance regression on Go 1.26. [#18568](prometheus/prometheus#18568) - \[BUGFIX] PromQL: Fix `info()` function incorrectly handling negated `__name__` matchers [#17932](prometheus/prometheus#17932) - \[BUGFIX] API: Return duration expressions in `/parse_ast`. [#18624](prometheus/prometheus#18624) - \[BUGFIX] API: correctly document formats accepted for duration query request parameters (step, timeout and lookback delta) in OpenAPI spec [#18305](prometheus/prometheus#18305) - \[BUGFIX] Scrape: AppenderV2 now tracks staleness even when OOO/duplicate series errors happen similar to AppenderV1 [#18567](prometheus/prometheus#18567) - \[BUGFIX] Config: Validate remote\_write queue\_config fields at load time to prevent runtime panic and silent misconfiguration. [#18209](prometheus/prometheus#18209) - \[BUGFIX] Discovery/Consul: Add `health_filter` for Health API filtering, fixing breakage when using Catalog-only fields like `ServiceTags` in `filter`. [#18479](prometheus/prometheus#18479) [#18499](prometheus/prometheus#18499) - \[BUGFIX] OTLP: limit decompressed body size for gzip-encoded OTLP write requests. [#18408](prometheus/prometheus#18408) - \[BUGFIX] PromQL: Fix `smoothed` rate/increase returning zero instead of no result when all data falls strictly after the query range. [#18523](prometheus/prometheus#18523) - \[BUGFIX] PromQL: Fix metric name not being dropped when last\_over\_time or first\_over\_time is applied to subqueries containing name-dropping functions like abs(). [#18409](prometheus/prometheus#18409) - \[BUGFIX] PromQL: Fix missing warning when mixing exponential and custom-bucket histograms in stats queries. [#18660](prometheus/prometheus#18660) - \[BUGFIX] PromQL: Fix parsing of `range()` keyword in duration expressions such as `foo[5m+range()]`. [#18623](prometheus/prometheus#18623) - \[BUGFIX] PromQL: Fix smoothed vector selector returning no results in binary operations when the `@` modifier is used. [#18531](prometheus/prometheus#18531) - \[BUGFIX] PromQL: Reject NaN, infinite, and out-of-range duration expressions instead of silently producing an out-of-range time.Duration. [#18639](prometheus/prometheus#18639) - \[BUGFIX] Scrape: Fix panic when scraping malformed native histograms. [#18414](prometheus/prometheus#18414) - \[BUGFIX] Scrape: fix panic when scraping a target exposing a summary with no quantiles via the protobuf format. [#18382](prometheus/prometheus#18382) - \[BUGFIX] Scrape: fix scrape failure log file occasionally not applied after a configuration reload. [#18421](prometheus/prometheus#18421) - \[BUGFIX] TSDB: Allow retention percentage with new data path. [#18628](prometheus/prometheus#18628) - \[BUGFIX] TSDB: Preserve decimal precision in percentage-based retention [#18374](prometheus/prometheus#18374) - \[BUGFIX] TSDB: fix prometheus\_tsdb\_head\_chunks going negative after WAL replay [#18401](prometheus/prometheus#18401) - \[BUGFIX] TSDB: panic with native histograms during query of overlapping chunks. [#18692](prometheus/prometheus#18692) - \[BUGFIX] Tracing: fix startup failure for insecure OTLP HTTP tracing [#18469](prometheus/prometheus#18469) - \[BUGFIX] UI: Escape label values offered by PromQL autocomplete. [#18658](prometheus/prometheus#18658) - \[BUGFIX] UI: Improve Y-axis tick label precision for graph values over small ranges. [#18682](prometheus/prometheus#18682) - \[BUGFIX] `prometheus_sd_refresh*` and `prometheus_sd_discovered_targets` metrics for specific scrape jobs are deleted when the scrape job is removed. [#17614](prometheus/prometheus#17614) - \[BUGFIX] Remote: fixed validation for received RW2 requests when parsing metadata unit symbols. This fixes a case when request would cause (recovered) handler panic. [#18641](prometheus/prometheus#18641) - \[BUGFIX] TSDB/Agent: fix race in agent appender where concurrent appends for the same label set could produce duplicate in-memory series and duplicate WAL records. [#18292](prometheus/prometheus#18292) - \[BUGFIX] Config: Update `--enable-feature` flag description and sort feature names. [#18487](prometheus/prometheus#18487)

jcreixell requested review from a team, bwplotka, codesome, jesusvazquez and krajorama as code owners March 30, 2026 11:57

jcreixell mentioned this pull request Mar 30, 2026

tsdb: compute head chunk count for status #17775

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Merge branch 'prometheus:main' into fix/negative-head-chunks-gauge

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krajorama self-assigned this Mar 31, 2026

jcreixell added 2 commits March 31, 2026 13:36

Simplify test

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- Re-use appending helper - Cleanup comments Signed-off-by: Jorge Creixell <jcreixell@gmail.com>

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Signed-off-by: Jorge Creixell <jcreixell@gmail.com>

jcreixell force-pushed the fix/negative-head-chunks-gauge branch from 4f87e09 to 0fbcb1f Compare March 31, 2026 11:37

Fix formatting

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Signed-off-by: Jorge Creixell <jcreixell@gmail.com>

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Co-authored-by: George Krajcsovits <krajorama@users.noreply.github.com> Signed-off-by: Jorge Creixell <jcreixell@gmail.com>

krajorama approved these changes Apr 1, 2026

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krajorama merged commit 4b562bb into prometheus:main Apr 1, 2026
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aknuds1 mentioned this pull request Jun 12, 2026

tsdb: preserve WAL replay accounting and ordering after full deletion #18907

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tsdb: fix prometheus_tsdb_head_chunks going negative after WAL replay#18401

tsdb: fix prometheus_tsdb_head_chunks going negative after WAL replay#18401
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jcreixell commented Mar 30, 2026

What this fixes

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jcreixell commented Mar 31, 2026 •

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