Fix image sync detection to log both source and target digests for debugging

[deepsm007]

Improves logging in ci-images-mirror to include both source and target digests when skipping image sync operations.

Currently, when ci-images-mirror determines that an image is already in sync (source and target digests match), it logs a debug message but only includes the target digest. This makes it difficult to debug cases where:

• Images appear to be out of sync (e.g., different release labels) but are marked as "already in sync"
• The digest comparison logic needs verification
• Troubleshooting requires manual cross-referencing of multiple log entries

The "Image needs sync" log already includes both digests for comparison, but the "already in sync" log was missing this critical information.

Manual verification showed the images are out of sync:
Source image (internal registry for app.ci): Release label 202601261115.p2.gf3ceb77.assembly.stream.el9
Target image (QCI): Release label 202601201943.p2.g7a68b22.assembly.stream.el9

Example

Before:
{"level":"debug","msg":"Image already in sync, skipping","target":"quay.io/openshift/ci:ocp_4.22_base-rhel9","digest":"sha256:3955031d..."}
After:
{"level":"debug","msg":"Image already in sync, skipping","target":"quay.io/openshift/ci:ocp_4.22_base-rhel9","source":"registry.ci.openshift.org/ocp/4.22:base-rhel9","sourceDigest":"sha256:3955031d...","targetDigest":"sha256:3955031d..."}

[openshift-ci-robot]

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[coderabbitai]

Walkthrough

A single file receives logging enhancements and comment clarifications in the mirror digest comparison logic. The changes add detailed logging when digests match, insert debug information via "Image needs sync" messages, and expand comments to clarify target digest behavior.

Changes

Cohort / File(s)	Summary
Logging and comment enhancements cmd/ci-images-mirror/main.go	Enhanced logging to include target, source, sourceDigest, and targetDigest fields when digests match. Added info-level log "Image needs sync" with digest details before proceeding. Expanded comments to clarify behavior when target digest is empty.

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~3 minutes

✨ Finishing touches

• 📝 Generate docstrings

---

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[coderabbitai]

Actionable comments posted: 0

Caution

Some comments are outside the diff and can’t be posted inline due to platform limitations.

⚠️ Outside diff range comments (1)

cmd/ci-images-mirror/main.go (1)

199-207: Remove duplicate “Image needs sync” log entry.

Two identical Info logs will fire back-to-back, producing redundant noise. Keep only one.

🛠️ Proposed fix

-		// Log sync needed with digest details for debugging
-		s.logger.WithField("source", source).WithField("target", targetImage).
-			WithField("sourceDigest", sourceInfo.Digest).WithField("targetDigest", targetInfo.Digest).
-			Info("Image needs sync")
-
 		s.logger.WithField("source", source).WithField("target", targetImage).
 			WithField("sourceDigest", sourceInfo.Digest).WithField("targetDigest", targetInfo.Digest).
 			Info("Image needs sync")

[openshift-ci]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: deepsm007, Prucek

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• OWNERS [Prucek,deepsm007]

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[openshift-ci-robot]

/retest-required

Remaining retests: 0 against base HEAD 9c27eed and 2 for PR HEAD 9757457 in total

[openshift-ci-robot]

Scheduling required tests:
/test e2e

Scheduling tests matching the pipeline_run_if_changed or not excluded by pipeline_skip_if_only_changed parameters:
/test integration-optional-test

[openshift-ci]

@deepsm007: The following test failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
ci/prow/breaking-changes	9757457	link	false	/test breaking-changes

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