Fix(log flags): handle log streams correctly by lxuan94-pp · Pull Request #8836 · kubernetes/autoscaler

lxuan94-pp · 2025-11-20T19:56:44Z

What type of PR is this?

/kind bug

Optionally add one or more of the following kinds if applicable:
/kind regression

What this PR does / why we need it:

After upgrading to Autoscaler v1.30.x, the log file no longer exists and is not created. This PR fixes the issue without modifying component-base or klog in vendor

Which issue(s) this PR fixes:

Fixes #7842

Special notes for your reviewer:

Persist the behavior from klog:

commandLine.StringVar(&logging.logFile, "log_file", "", "If non-empty, use this log file (no effect when -logtostderr=true)")
commandLine.BoolVar(&logging.toStderr, "logtostderr", true, "log to standard error instead of files")
commandLine.BoolVar(&logging.alsoToStderr, "alsologtostderr", false, "log to standard error as well as files (no effect when -logtostderr=true)")

Does this PR introduce a user-facing change?

None

For more information on release notes see: https://git.k8s.io/community/contributors/guide/release-notes.md
-->

Fixed an issue where the --log-file option stopped working. Logging now correctly writes to the specified file in addition to standard error.

Additional documentation e.g., KEPs (Kubernetes Enhancement Proposals), usage docs, etc.:

Tested in OCI cluster

k8s-ci-robot · 2025-11-20T19:56:54Z

Hi @lxuan94-pp. Thanks for your PR.

I'm waiting for a github.com member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

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jackfrancis · 2025-11-20T23:38:18Z

 sigs.k8s.io/structured-merge-diff/v6 v6.3.0/go.mod h1:M3W8sfWvn2HhQDIbGWj3S099YozAsymCo/wrT5ohRUE=
 sigs.k8s.io/yaml v1.6.0 h1:G8fkbMSAFqgEFgh4b1wmtzDnioxFCUgTZhlbj5P9QYs=
-sigs.k8s.io/yaml v1.6.0/go.mod h1:796bPqUfzR/0jLAl6XjHl3Ck7MiyVv8dbTdyT3/pMf4=
+sigs.k8s.io/yaml v1.6.0/go.mod h1:796bPqUfzR/0jLAl6XjHl3Ck7MiyVv8dbTdyT3/pMf4=


please remove this newline change, thank you!

I think it was changed by go mod tidy I ran, which caused different line endings. I have reverted it to the master version.

…stderr logging.

jackfrancis · 2025-11-21T19:50:12Z

+	// default: both to stderr
+	var infoW, errW io.Writer = os.Stderr, os.Stderr
+
+	if logFilePath != "" && !logToStderr {


Can we drop the -alsologtostderr option?

If just --log-file is set but no --logtostderr (default to false), then we configure logging for redirecting both info and err logging to the configured log file.

If --log-file is set and --logtostderr=true we intrepret that as:

configure logging for redirecting both info and err logging to the configured log file

also tee log info and err output to stderr

We can drop -alsologtostderr if we want to follow this model, but just to note: klog’s guidance is that --log-file and --alsologtostderr are ignored when --logtostderr=true

commandLine.StringVar(&logging.logFile, "log_file", "", "If non-empty, use this log file (no effect when -logtostderr=true)") commandLine.BoolVar(&logging.toStderr, "logtostderr", true, "log to standard error instead of files") commandLine.BoolVar(&logging.alsoToStderr, "alsologtostderr", false, "log to standard error as well as files (no effect when -logtostderr=true)")

from klog/v2 https://pkg.go.dev/k8s.io/klog/v2#klog.go

I’m fine proceeding with your proposed interpretation, as long as we’re aware it slightly diverges from the standard klog usage pattern. Let me know if you want me to update the flags accordingly.

@jackfrancis Please advise on how we should proceed, and I can update or keep the change accordingly.

ACK, probably best not to overthink and follow that guidance

jackfrancis · 2025-11-21T19:50:30Z

/ok-to-test

jackfrancis · 2025-11-26T21:29:06Z

/test pull-cluster-autoscaler-e2e-azure-master

lxuan94-pp · 2025-12-15T21:41:14Z

Hi @jackfrancis, pls check the comment #8836 (comment) and advise on how we should proceed. IMO I want to keep the current behavior to align with klog.

lxuan94-pp · 2026-01-14T16:11:13Z

Bumping #8836 (comment)
cc:@jackfrancis

jackfrancis

/lgtm
/approve

jackfrancis · 2026-01-22T15:50:23Z

+	// default: both to stderr
+	var infoW, errW io.Writer = os.Stderr, os.Stderr
+
+	if logFilePath != "" && !logToStderr {


ACK, probably best not to overthink and follow that guidance

k8s-ci-robot · 2026-01-22T15:51:08Z

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: jackfrancis, lxuan94-pp

The full list of commands accepted by this bot can be found here.

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Needs approval from an approver in each of these files:

~~cluster-autoscaler/OWNERS~~ [jackfrancis]

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jackfrancis · 2026-01-22T15:57:52Z

/cherry-pick cluster-autoscaler-release-1.32

k8s-infra-cherrypick-robot · 2026-01-22T15:58:32Z

@jackfrancis: new pull request created: #9101

Details

In response to this:

/cherry-pick cluster-autoscaler-release-1.32

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jackfrancis · 2026-01-22T15:59:55Z

/cherry-pick cluster-autoscaler-release-1.33
/cherry-pick cluster-autoscaler-release-1.34
/cherry-pick cluster-autoscaler-release-1.35

k8s-infra-cherrypick-robot · 2026-01-22T16:00:34Z

@jackfrancis: new pull request created: #9102

Details

In response to this:

/cherry-pick cluster-autoscaler-release-1.33
/cherry-pick cluster-autoscaler-release-1.34
/cherry-pick cluster-autoscaler-release-1.35

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository.

k8s-infra-cherrypick-robot · 2026-01-22T16:01:12Z

@jackfrancis: new pull request created: #9103

Details

In response to this:

/cherry-pick cluster-autoscaler-release-1.33
/cherry-pick cluster-autoscaler-release-1.34
/cherry-pick cluster-autoscaler-release-1.35

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository.

k8s-infra-cherrypick-robot · 2026-01-22T16:01:49Z

@jackfrancis: new pull request created: #9104

Details

In response to this:

/cherry-pick cluster-autoscaler-release-1.33
/cherry-pick cluster-autoscaler-release-1.34
/cherry-pick cluster-autoscaler-release-1.35

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository.

k8s-ci-robot requested review from BigDarkClown and aleksandra-malinowska November 20, 2025 19:56

k8s-ci-robot added the needs-ok-to-test Indicates a PR that requires an org member to verify it is safe to test. label Nov 20, 2025

lxuan94-pp force-pushed the xl/klog-file branch from 1010e06 to 9ad01ac Compare November 20, 2025 19:59

k8s-ci-robot added size/L Denotes a PR that changes 100-499 lines, ignoring generated files. and removed size/S Denotes a PR that changes 10-29 lines, ignoring generated files. labels Nov 20, 2025

lxuan94-pp force-pushed the xl/klog-file branch from 9ad01ac to 3de2db7 Compare November 20, 2025 20:09

k8s-ci-robot removed the needs-rebase Indicates a PR cannot be merged because it has merge conflicts with HEAD. label Nov 20, 2025

lxuan94-pp force-pushed the xl/klog-file branch from 3de2db7 to de1f71e Compare November 20, 2025 20:13

jackfrancis requested changes Nov 20, 2025

View reviewed changes

lxuan94-pp force-pushed the xl/klog-file branch from de1f71e to 7f925c7 Compare November 21, 2025 01:53

Handle log streams correctly for default stderr, file-only, and file+…

72888ba

…stderr logging.

lxuan94-pp force-pushed the xl/klog-file branch from 7f925c7 to 72888ba Compare November 21, 2025 01:57

jackfrancis reviewed Nov 21, 2025

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k8s-ci-robot added the ok-to-test Indicates a non-member PR verified by an org member that is safe to test. label Nov 21, 2025

k8s-ci-robot removed the needs-ok-to-test Indicates a PR that requires an org member to verify it is safe to test. label Nov 21, 2025

lxuan94-pp requested a review from jackfrancis November 25, 2025 22:53

jackfrancis approved these changes Jan 22, 2026

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k8s-ci-robot assigned jackfrancis Jan 22, 2026

k8s-ci-robot added the lgtm "Looks good to me", indicates that a PR is ready to be merged. label Jan 22, 2026

k8s-ci-robot added the approved Indicates a PR has been approved by an approver from all required OWNERS files. label Jan 22, 2026

k8s-ci-robot merged commit 872d31f into kubernetes:master Jan 22, 2026
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k8s-infra-cherrypick-robot mentioned this pull request Jan 22, 2026

[cluster-autoscaler-release-1.32] Fix(log flags): handle log streams correctly #9101

Closed

k8s-infra-cherrypick-robot mentioned this pull request Jan 22, 2026

[cluster-autoscaler-release-1.33] Fix(log flags): handle log streams correctly #9102

Merged

k8s-infra-cherrypick-robot mentioned this pull request Jan 22, 2026

[cluster-autoscaler-release-1.34] Fix(log flags): handle log streams correctly #9103

Merged

k8s-infra-cherrypick-robot mentioned this pull request Jan 22, 2026

[cluster-autoscaler-release-1.35] Fix(log flags): handle log streams correctly #9104

Merged

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