feat: queue time capture for Rack by dingsdax · Pull Request #2838 · getsentry/sentry-ruby

dingsdax · 2026-01-15T10:20:31Z

Captures how long requests wait for a e.g. Puma thread from X-Request-Start headers and attaches it to transactions as http.server.request.time_in_queue. Sentry only measures after Puma picks up the request. Under load, requests might wait long in the queue but only take a fraction to process. Similar to what judoscale and scout do.

works with all major reverse proxies:

Nginx: X-Request-Start: t=1234567890.123 (seconds)
Heroku: X-Request-Start: t=1234567890123456 (microseconds)
HAProxy 1.9+: X-Request-Start: t=1234567890123456 (microseconds)
HAProxy < 1.9: X-Request-Start: t=1234567890 (seconds)
Generic: Raw timestamps in seconds/milliseconds/microseconds

subtracts puma.request_body_wait for accuracy (excludes slow client uploads from queue time).

Usage

works 🤞 if your reverse proxy sets the header:

# Nginx
proxy_set_header X-Request-Start "t=${msec}";

opt-out

config.capture_queue_time = false

resolves: Add Puma request queue time as a transaction attribute #2813
resolves: RUBY-130

default to true

linear · 2026-01-15T10:20:35Z

RUBY-130 Add Puma request queue time as a transaction attribute

github-actions · 2026-01-15T10:20:57Z

	Messages
📖	Do not forget to update Sentry-docs with your feature once the pull request gets approved.

Generated by 🚫 dangerJS against 3cc6f8a

sentry-ruby/lib/sentry/rack/capture_exceptions.rb

sl0thentr0py · 2026-01-15T13:03:58Z

sentry-ruby/lib/sentry/span.rb

      MESSAGING_MESSAGE_RETRY_COUNT = "messaging.message.retry.count"
+
+      # Time in ms the request spent in the server queue before processing began.
+      HTTP_QUEUE_TIME_MS = "http.queue_time_ms"


@AbhiPrasad @lcian is there an attribute convention for time spent in queue waiting for the http request to be picked up in an HTTP server?

The closest I could find is http.client.request.time_in_queue but that's for clients.

Hmmm I cannot find anything like that. Maybe we introduce our own http.server.request.time_in_queue counterpart?

sounds good; shall I add to sentry-conventions too?

sl0thentr0py

some small stuff, and mainly want to wait for feedback on the attribute convention name

sentry-ruby/lib/sentry/rack/capture_exceptions.rb

sentry-ruby/test-app/sentry_queue_test.rb

sentry-ruby/spec/sentry/rack/capture_exceptions_spec.rb

Co-authored-by: Neel Shah <neel.shah@sentry.io>

sentry-ruby/lib/sentry/rack/capture_exceptions.rb

solnic

✅ but I left a bunch of minor 💅🏻 suggestions 🙃

sentry-ruby/lib/sentry/rack/capture_exceptions.rb

Co-authored-by: Peter Solnica <peter@solnica.online>

Non-numeric t= values like "t=invalid" or "t=" were silently converted to 0.0 by Ruby's String#to_f, resulting in a Unix epoch timestamp and a queue time of ~56 years instead of nil. Apply the same numeric regex guard already used for raw timestamps to the t= branch before calling to_f. Co-Authored-By: Claude <noreply@anthropic.com>

Co-authored-by: Peter Solnica <peter@solnica.online>

sentry-ruby/lib/sentry/rack/capture_exceptions.rb

parse_request_start_header returned nil for headers that arrived with leading/trailing whitespace or as comma-separated values (multiple header occurrences collapsed by a proxy). Strip whitespace from the token and split on commas, taking the first (earliest) timestamp. Co-Authored-By: Claude <noreply@anthropic.com>

When env["puma.request_body_wait"] is a String (e.g. serialized by middleware), the `> 0` comparison raised ArgumentError, which was silently swallowed by the broad rescue, causing queue time to be dropped even with a valid X-Request-Start header. Call to_f on String values before the comparison. Numeric strings ("40") convert correctly; non-numeric strings ("N/A") become 0.0 and are treated as absent, so total_time_ms is returned unchanged. Co-Authored-By: Claude <noreply@anthropic.com>

…-ruby into puma-queue-time

cursor

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cursor · 2026-02-24T15:51:08Z

sentry-ruby/lib/sentry/rack/capture_exceptions.rb

+          queue_time_ms >= 0 ? queue_time_ms : 0.0 # more sanity check
+        else
+          total_time_ms
+        end


Queue time spoofable via client header

Medium Severity

extract_queue_time trusts env["HTTP_X_REQUEST_START"] without verifying it was set/overwritten by a trusted proxy and without any upper-bound sanity check, so a client-supplied X-Request-Start can inject arbitrarily large http.server.request.time_in_queue values and skew transaction data.

Adds the `http.server.request.time_in_queue` semantic convention attribute to capture the time (in milliseconds) a request spent waiting in the server queue before processing began. This attribute is populated from the `X-Request-Start` header set by reverse proxies (Nginx, HAProxy, Heroku router, etc.) and first introduced in sentry-ruby: getsentry/sentry-ruby#2838 Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* feat(http): add http.server.request.time_in_queue attribute Adds the `http.server.request.time_in_queue` semantic convention attribute to capture the time (in milliseconds) a request spent waiting in the server queue before processing began. This attribute is populated from the `X-Request-Start` header set by reverse proxies (Nginx, HAProxy, Heroku router, etc.) and first introduced in sentry-ruby: getsentry/sentry-ruby#2838 Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com> * feat(http): add generated attribute definitions for http.server.request.time_in_queue Generate TypeScript and Python attribute definitions including type exports, metadata entries, and TypedDict annotations. Co-Authored-By: Claude <noreply@anthropic.com> --------- Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

dingsdax added 3 commits January 15, 2026 09:41

add configuration for capturing queue time

39a875b

default to true

Extract, normalize & add queue time to transaction

8b2e2b8

Test app for queue time in Sentry

7829e24

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dingsdax requested review from sl0thentr0py and solnic and removed request for solnic January 15, 2026 10:22

dingsdax marked this pull request as ready for review January 15, 2026 10:23

dingsdax added 4 commits January 15, 2026 11:26

Fix redos issue

dfea02f

move test app

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Update CHANGELOG.md

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Update CHANGELOG.md

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dingsdax mentioned this pull request Jan 15, 2026

feat: queue time metric getsentry/sentry-docs#16030

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Update sentry-ruby/lib/sentry/rack/capture_exceptions.rb

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Co-authored-by: Neel Shah <neel.shah@sentry.io>

Delete sentry_queue_test.rb

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Update sentry-ruby/lib/sentry/rack/capture_exceptions.rb

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Co-authored-by: Peter Solnica <peter@solnica.online>

Update sentry-ruby/lib/sentry/rack/capture_exceptions.rb

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Co-authored-by: Peter Solnica <peter@solnica.online>

Update sentry-ruby/lib/sentry/rack/capture_exceptions.rb

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Co-authored-by: Peter Solnica <peter@solnica.online>

dingsdax and others added 5 commits February 24, 2026 14:33

Update sentry-ruby/lib/sentry/rack/capture_exceptions.rb

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Update sentry-ruby/lib/sentry/rack/capture_exceptions.rb

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Co-authored-by: Peter Solnica <peter@solnica.online>

Update sentry-ruby/lib/sentry/rack/capture_exceptions.rb

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Co-authored-by: Peter Solnica <peter@solnica.online>

Update sentry-ruby/lib/sentry/rack/capture_exceptions.rb

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Co-authored-by: Peter Solnica <peter@solnica.online>

Update sentry-ruby/lib/sentry/rack/capture_exceptions.rb

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Co-authored-by: Peter Solnica <peter@solnica.online>

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dingsdax and others added 5 commits February 24, 2026 14:35

Merge branch 'master' into puma-queue-time

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Merge branch 'puma-queue-time' of https://github.com/getsentry/sentry…

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…-ruby into puma-queue-time

Merge branch 'master' into puma-queue-time

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dingsdax mentioned this pull request Feb 24, 2026

feat(http): add http.server.request.time_in_queue attribute getsentry/sentry-conventions#267

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sl0thentr0py deleted the puma-queue-time branch February 25, 2026 11:33

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publish: getsentry/sentry-ruby@6.4.0 getsentry/publish#7262

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Queue time spoofable via client header

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