Add Slack build notification action#432
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Composite action that sends Slack notifications on build state transitions on main. Detects when a previously-passing workflow starts failing, and when a previously-failing workflow recovers. - Queries GitHub API for previous workflow run conclusions - Skips cancelled runs when determining state transitions - Failure messages include failed job/step names with links - Recovery messages include consecutive failure count and date - Uses Slack Block Kit for structured messages
- Wrap entire script in try/catch, warning on error - Add text fallback to Slack payload for notification previews - Handle empty failure details with informative fallback - Increase job listing page size to 100 for large matrices
- Add github.repository_owner == 'posit-dev' guard so the notification only fires in posit-dev repos - Document the state comparison mismatch between alls-green (build-only) and workflow conclusion (all jobs including clean)
Query the previous run's jobs and compare the CI meta-job's conclusion instead of the workflow-level conclusion. This prevents clean-job flaps from triggering false recovery notifications. Falls back to workflow conclusion if no CI job is found.
Sanitize &, <, > in commit message text before inserting into Slack Block Kit mrkdwn to prevent injection of mentions like <!here> or formatting breakage.
Show at most 5 failed jobs with an "… and N more" summary when there are many failures (e.g. content image matrix). Include total failed job count in the header line.
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Pull request overview
Adds a new reusable composite GitHub Action to post Slack notifications when CI transitions between passing and failing states, intended for use by image repos’ CI meta-job on main.
Changes:
- Introduces
.github/actions/slack-build-notify/composite action usingactions/github-scriptto compare current vs previous run state. - Sends Slack Block Kit messages for “failure” (with failed job/step details) and “recovery” (with consecutive failure count).
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ianpittwood
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Apr 9, 2026
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LGTM but some of the Copilot feedback may be actionable
Include timed_out and action_required conclusions in the failed job list, not just failure. A timed-out job would otherwise show "No individual job failures identified."
Extract previousConclusion variable so the log message reflects the CI job conclusion when available, matching the value actually used for state transition comparison.
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Summary
Adds a reusable composite action at
.github/actions/slack-build-notify/that sends Slack notifications on build state transitions onmain:Designed for use in the CI meta-job across product image repos (
images-connect,images-package-manager,images-workbench).Design decisions
actions/github-scriptfor pre-authenticated GitHub API accesscontinue-on-errorin callers so notification issues never block CIposit-dev/repos viagithub.repository_ownerguardtextfallback for notification previewsRequired setup
Each product repo needs a
SLACK_WEBHOOK_URLrepository secret pointing at the#platform-builds-imageschannel webhook.Test plan
SLACK_WEBHOOK_URLsecret to a test repomainand verify Slack message appears