PMM-15361 Widen the healthcheck grace to 90s - #5808
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A cold boot against an empty volume does not reach readyz before the 25s start period elapses, so three failed probes mark the container unhealthy at roughly 37s and it recovers a few seconds later. Anything gated on condition: service_healthy - pmm-client in our own compose file included - aborts if compose polls inside that window. One of three cold runs failed that way on fast local storage; slower hardware loses the race more often. 180s covers the slowest cold start observed with headroom. A healthy boot is unaffected, since the start period ends at the first passing probe; a genuinely wedged server now reports unhealthy after three minutes instead of thirty-seven seconds. Signed-off-by: Yan Orestes <yan.orestes@percona.com>
Codecov Report✅ All modified and coverable lines are covered by tests. Additional details and impacted files@@ Coverage Diff @@
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WalkthroughChangesServer health check The EL9 server image health check start period decreases from 180 to 90 seconds. The readiness endpoint, interval, timeout, retries, and timing comment remain unchanged. Merge Risk: 🟡 Moderate · up to The PR widens pmm-server’s healthcheck grace period, but related Compose overrides still use shorter or default periods, so dependent services may continue to abort during slow cold starts; the current image setting also differs from the stated 180-second target. These configuration inconsistencies should be resolved or explicitly accepted before merge. 🚥 Pre-merge checks | ✅ 4✅ Passed checks (4 passed)
Full details: Description checkExplanation The description clearly explains the cold-boot failure, the healthcheck change, measured timings, impact, rationale, and testing status. It omits the template fields for the ticket number, feature build, and API documentation checkbox, but the substantive description is complete and on topic. Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out. Comment |
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Actionable comments posted: 1
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Inline comments:
In `@build/docker/server/Dockerfile.el9`:
- Around line 53-55: Update the historical timing comment near the HEALTHCHECK
to state that the former settings marked the container unhealthy at roughly 37
seconds after three post-grace failures, rather than at 25 seconds; explicitly
identify those values as previous settings and distinguish them from the current
180-second start period.
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Pull request overview
Extends the PMM Server health-check grace period to accommodate cold starts and prevent dependent Compose services from aborting prematurely.
Changes:
- Increases the health-check start period from 25s to 180s.
- Documents the measured startup timings and rationale.
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25s was when the grace period ended, not when the container was marked unhealthy - three failed probes after it put that around 34s, which is what the measurement showed. The comment also read as if 25s were still the configured value, on the line above a start period of 180s. Signed-off-by: Yan Orestes <yan.orestes@percona.com>
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Corroborating measurement from a second machine Hit this on the PMM+SEP paired feature-build stack, where a SEP side-car is gated on
Worth it for the framing: the 34s on fast local storage is 3s under the 37s threshold, so it reads as a flake; ~72s is 35s over, so it fails deterministically. Same defect — the two numbers bracket it better than either alone does. |
Review preferred keeping the grace tight enough to still catch a startup regression, so 180s comes down to 90s. That clears the cold boots measured here - 34s to first pass readyz on fast local storage, and ~72s on a loaded stack where a dependent and its database co-start - and the slowest observation, near 90s on slower hardware, is absorbed by the three post-grace retries. A server that never reaches readyz at all now reports unhealthy at about 102s rather than 192s. Signed-off-by: Yan Orestes <yan.orestes@percona.com>
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| # before that, so three failed probes marked the container unhealthy around 34s, | ||
| # and a dependent gated on service_healthy aborted whenever compose polled during | ||
| # the few seconds before it recovered. | ||
| HEALTHCHECK --interval=4s --timeout=2s --start-period=90s --retries=3 CMD curl -sf http://127.0.0.1:8080/v1/server/readyz |
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🩺 Stability & Availability | 🟠 Major | 🏗️ Heavy lift
Update the downstream healthcheck overrides.
This image-level --start-period=90s does not affect percona/pmm-qa Compose files that replace the image healthcheck. qa-integration/pmm_psmdb_diffauth_setup/docker-compose-pmm-psmdb.yml:70-78 has no start_period, and codeceptjs-e2e/docker-compose-clickhouse.yml:31-38 uses 60s. These stacks can still mark pmm-server unhealthy before the measured 72–90 second cold boot completes.
Align those overrides with the 90-second budget or remove them, then verify the affected stacks.
Source: Linked repositories
yyyyyyyan
changed the title
A cold
docker compose upmarkspmm-serverunhealthy for a few seconds before it becomes healthy, so anything gated ondepends_on: {pmm-server: {condition: service_healthy}}aborts when compose polls inside that window.pmm-clientin our owndocker-compose.ymlis gated that way.What happens
--start-period=25sstops absorbing probe failures before a cold boot reachesreadyz. Three failures at 4s intervals then mark the container unhealthy at roughly 37s, and it recovers a few seconds later.Measured on a cold boot against an empty volume, fast local storage:
With a dependent gated on
condition: service_healthy, three cold runs gave two passes and one failure:A separate measurement on slower hardware put the cold start near 90s, which widens the window and loses the race far more often than one in three.
The change
--start-period25s → 90s, with a comment recording what the number is sized against.A healthy boot is unaffected — the start period ends at the first passing probe, so nothing waits longer than it does today. The cost is that a genuinely wedged server reports unhealthy after about 102s rather than thirty-seven seconds. This opened at 180s; review preferred keeping that verdict tight enough to still catch a startup regression, and 90s clears every cold boot measured here.
Notes
Present since the EL9 image landed in 2023 (
7a6862e18); not a recent regression. It surfaced during PMM-15205 work because that stack briefly carried a 720s start period for unrelated reasons, which masked it.The comment matters as much as the value here. The 720s above went unexamined for months because its stated rationale had stopped being the real one, and it was then reverted without anyone re-deriving what it was for.
Tested
docker inspecthealth transitions onperconalab/pmm-server-fb:PR-4500-7dcd575.docker compose upruns with a dependent gated onservice_healthy, before the change: 2 pass, 1 fail.HEALTHCHECKinstruction itself, so it needs a build to exercise. Worth confirming in a Feature Build that the instruction lands as intended and that the same gate passes repeatedly.