Reduce MachineConfigNodeFailed event spam during SNO upgrades - #6444
Reduce MachineConfigNodeFailed event spam during SNO upgrades#6444redhat-chai-bot wants to merge 3 commits into
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During a Single Node OpenShift (SNO) upgrade the node reboots and takes
the kube-apiserver down with it. The machine-config-daemon sync/resync
loop keeps running and every attempt fails with:
dial tcp 172.30.0.1:443: connect: connection refused
handleErr() re-marks the node Degraded and re-applies the
MachineConfigNode NodeDegraded ("failed") status on every one of those
attempts. Over a typical 5-10 minute outage this emits ~20-28 identical
failure reports in rapid succession, tripping the pathological-events
monitor (threshold ~20) and causing false CI test failures, even though
the upgrade ultimately succeeds.
Add an exponential backoff for connection-level errors (connection
refused/reset and host/network unreachable) in the daemon sync error
handler: the degraded state is still reported on the first failure, then
only on an exponentially growing schedule of consecutive connection
failures (1st, 2nd, 4th, 8th, 16th, ...). This collapses the ~28 reports
during an outage down to a handful while preserving prompt reporting of
genuine, actionable errors (which reset the backoff). The work queue's
existing exponential rate limiter continues to space out the retries
themselves.
This mirrors the event-spam reduction done for the machine-api-operator
during slow SNO rollouts (openshift/machine-api-operator#1526).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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Included review availability: Your plan provides up to 2 included reviews per hour; 0 remain after this review. WalkthroughThe daemon classifies API-server connectivity errors and applies exponential sync-error reporting backoff only on single-node clusters. Multi-node clusters report every sync error. Tests cover classification, reporting intervals, and counter resets. ChangesAPI-server sync-error backoff
Estimated code review effort: 3 (Moderate) | ~20 minutes Merge Risk: ⚪ Minimal · up to The change limits repeated degraded-state events during temporary API outages while preserving prompt reporting for the first failure and non-connectivity errors; no actionable merge-blocking risk remains beyond normal checks and review. Suggested reviewers: Sequence Diagram(s)sequenceDiagram
participant SyncWorker
participant Daemon
participant ErrorState
participant WorkQueue
SyncWorker->>Daemon: process synchronization result
alt single-node cluster
Daemon->>Daemon: classify error and update failure count
Daemon->>ErrorState: update degraded state when reportable
else multi-node cluster
Daemon->>Daemon: reset connectivity failure counter
Daemon->>ErrorState: update degraded state for every sync error
end
Daemon->>WorkQueue: apply retry rate limiting
🚥 Pre-merge checks | ✅ 14 | ❌ 1❌ Failed checks (1 warning)
✅ Passed checks (14 passed)
✨ Finishing Touches🧪 Generate unit tests (beta)
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Inline comments:
In `@pkg/daemon/daemon.go`:
- Around line 655-656: Update the backoff log in the daemon’s API-server
reachability handling to remove the raw err value and retain only the
consecutive failure count; leave the existing later log that records the error
unchanged.
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pkg/daemon/backoff.gopkg/daemon/backoff_test.gopkg/daemon/daemon.go
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/hold while @sadasu looks for a better solution than this or openshift/origin#31550 |
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The exponential backoff for API-unreachable errors was previously applied to all cluster topologies. On multi-node (HA) clusters, API-unreachable errors are uncommon and actionable, so they should always be reported immediately. This change gates the backoff behind an isSingleNodeTopology check so it only engages on SNO installs where the API server goes away during node reboots. Also removes the raw error from the backoff log line to avoid exposing internal API server addresses; the error is already logged on the following line. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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Inline comments:
In `@pkg/daemon/daemon.go`:
- Around line 653-654: In the HA handling branch of the daemon sync-error flow
around isSingleNodeTopology and shouldReportSyncError, reset
apiUnreachableFailures before processing the error. Add a regression test
covering a topology transition from SNO to HA and back, verifying stale backoff
failures are cleared when HA handles the sync error.
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pkg/daemon/backoff.gopkg/daemon/daemon.go
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- pkg/daemon/backoff.go
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The control-plane topology annotation can be updated by the node controller during the daemon's lifetime. A SNO -> HA -> SNO transition could leave apiUnreachableFailures holding a stale value from the earlier SNO outage, so the exponential backoff would resume mid-schedule on the return to SNO and wrongly suppress or delay legitimate MachineConfigNode failure reports. Reset apiUnreachableFailures in the HA branch of handleErr so multi-node clusters never carry over SNO backoff state, and add a regression test covering the SNO -> HA -> SNO topology transition. Addresses CodeRabbit review feedback on openshift#6444. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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Inline comments:
In `@pkg/daemon/backoff_test.go`:
- Around line 138-140: Update the regression test around the Phase 2 topology
transition to execute handleErr while the daemon is in HA topology, allowing the
production HA branch to reset apiUnreachableFailures; remove the direct
assignment of that counter and then verify the expected SNO schedule behavior.
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pkg/daemon/backoff_test.gopkg/daemon/daemon.go
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@sadasu Done — pushed in The HA branch now resets AI-generated. Review for accuracy. |
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/hold cancel @neisw I am happy with the fix now. |
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Summary
During single-node (SNO) OpenShift upgrades, the node reboots to apply MachineConfig changes. While the node is down, the kube-apiserver is unreachable and the machine-config-daemon's sync/resync loop (
processNextWorkItem→syncNode→handleErr) fails on every attempt with:Each failure triggers
updateErrorState→updateDegradedState, which re-marks the node Degraded and re-applies the MachineConfigNodeNodeDegradedstatus. This generates 20–28 identicalMachineConfigNodeFailedevents during a typical 5–10 minute API outage, tripping the pathological events monitor threshold of ~20 and causing false CI test failures.Changes
Adds exponential backoff to the degraded-state re-reporting for connection-level errors:
pkg/daemon/backoff.go(new)isAPIServerUnreachableError: detects connection refused/reset and host/network unreachable errors viak8s.io/apimachinery/pkg/util/net+ errno unwrapshouldReportUnreachable: power-of-two schedule (report on 1st, 2nd, 4th, 8th, 16th... attempt)Daemon.shouldReportSyncError: counter management integrating with the daemonpkg/daemon/daemon.goapiUnreachableFailurescounter toDaemonhandleErrnow only re-reports degraded state on exponentially-spaced attempts for connection errorspkg/daemon/backoff_test.go(new)Impact
Reduces ~28 identical
MachineConfigNodeFailedevents to ~5 during a typical SNO upgrade API outage, well below the pathological events threshold. No behavior change for multi-node clusters or non-connectivity errors.Analogous to machine-api-operator#1526 (event-spam reduction during slow SNO rollouts).
Jira
Related: OCPBUGS-112466
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@neisw requested in Slack thread
Summary by CodeRabbit
Bug Fixes
Tests