feat: add automated Slack release notifications (#1045)

* docs: add release validation and announcement sections to release guide

Add two new sections to the release guide:
- Release Validation: documents the current approach (e2e tests) and
  includes a validation checklist for before publishing
- Announce the Release: documents the Slack announcement process for
  #topic-cf-gitops-runtime and #team-support-announcements

* feat: add automated Slack release notifications

Add GitHub Actions workflow that posts to Slack when a release is published:
- Posts to #topic-cf-gitops-runtime with release version and link
- Cross-posts to #team-support-announcements
- Includes workflow_dispatch trigger for manual testing

Update release guide:
- Document that announcements are now automated
- Add troubleshooting section for Slack notifications
- Add Slack integration setup instructions in Reference section

Author: dmaizel

.github/workflows/release-notification.yaml

@@ -0,0 +1,59 @@
+# ABOUTME: GitHub Actions workflow that posts Slack notifications when a release is published.
+# ABOUTME: Notifies #topic-cf-gitops-runtime and cross-posts to #team-support-announcements.
+
+name: Release Notification
+
+on:
+  release:
+    types: [published]
+  workflow_dispatch:
+    inputs:
+      tag:
+        description: 'Release tag to simulate (e.g., 0.27.0)'
+        required: true
+
+jobs:
+  notify-slack:
+    runs-on: ubuntu-latest
+    env:
+      RELEASE_TAG: ${{ github.event.release.tag_name || inputs.tag }}
+      RELEASE_URL: ${{ github.event.release.html_url || format('https://github.com/{0}/releases/tag/{1}', github.repository, inputs.tag) }}
+    steps:
+      - name: Notify #topic-cf-gitops-runtime
+        uses: slackapi/[email protected]
+        with:
+          method: chat.postMessage
+          token: ${{ secrets.SLACK_BOT_TOKEN }}
+          payload: |
+            channel: ${{ vars.SLACK_CHANNEL_GITOPS_RUNTIME }}
+            text: "GitOps Runtime ${{ env.RELEASE_TAG }} has been released"
+            blocks:
+              - type: header
+                text:
+                  type: plain_text
+                  text: "🚀 GitOps Runtime Release"
+              - type: section
+                fields:
+                  - type: mrkdwn
+                    text: "*Version:*\n${{ env.RELEASE_TAG }}"
+              - type: actions
+                elements:
+                  - type: button
+                    text:
+                      type: plain_text
+                      text: "View Release Notes"
+                    url: ${{ env.RELEASE_URL }}
+
+      - name: Cross-post to #team-support-announcements
+        uses: slackapi/[email protected]
+        with:
+          method: chat.postMessage
+          token: ${{ secrets.SLACK_BOT_TOKEN }}
+          payload: |
+            channel: ${{ vars.SLACK_CHANNEL_SUPPORT_ANNOUNCEMENTS }}
+            text: "GitOps Runtime ${{ env.RELEASE_TAG }} has been released"
+            blocks:
+              - type: section
+                text:
+                  type: mrkdwn
+                  text: "*GitOps Runtime ${{ env.RELEASE_TAG }}* has been released.\n\n<${{ env.RELEASE_URL }}|View release notes>"

docs/RELEASE_GUIDE.md

@@ -18,12 +18,13 @@ The instructions below explain how to do everything manually if you prefer that
 2. [Prerequisites](#prerequisites)
 3. [Release Types](#release-types)
 4. [Creating a New Minor Release](#creating-a-new-minor-release)
-5. [Publishing a Release](#publishing-a-release)
-6. [Creating a Patch Release](#creating-a-patch-release)
-7. [Cherry-Picking Fixes](#cherry-picking-fixes)
-8. [Writing Release Notes](#writing-release-notes)
-9. [Troubleshooting](#troubleshooting)
-10. [Reference](#reference)
+5. [Release Validation](#release-validation)
+6. [Publishing a Release](#publishing-a-release)
+7. [Creating a Patch Release](#creating-a-patch-release)
+8. [Cherry-Picking Fixes](#cherry-picking-fixes)
+9. [Writing Release Notes](#writing-release-notes)
+10. [Troubleshooting](#troubleshooting)
+11. [Reference](#reference)
 
 ---
 
@@ -141,6 +142,27 @@ Or visit:
 
 ---
 
+## Release Validation
+
+After the prepare-release PR is automatically created and before publishing the release, the release should be validated to ensure stability.
+
+### Current Approach
+
+The CI pipeline runs e2e tests on every PR. If these tests pass, the release is considered validated and ready to publish.
+
+> **Note**: Previously, releases were validated by deploying to staging environments and letting them run for a period before publishing. This approach is no longer in use. If additional validation is needed in the future, consider introducing a manual testing stage or dedicated validation environments.
+
+### Validation Checklist
+
+Before publishing, ensure:
+
+- [ ] All CI checks pass (unit tests, linting, e2e tests)
+- [ ] The prepare-release PR has been reviewed
+- [ ] Release notes accurately reflect the changes
+- [ ] No known critical issues exist in the changes being released
+
+---
+
 ## Publishing a Release
 
 ### Step 1: Check PR Status
@@ -186,6 +208,14 @@ Check the release:
 gh release view 0.27.0 --repo codefresh-io/gitops-runtime-helm
 ```
 
+### Step 5: Announcement (Automated)
+
+When a release is published, a GitHub Actions workflow automatically posts announcements to:
+- `#topic-cf-gitops-runtime` - Primary announcement with release version and link
+- `#team-support-announcements` - Cross-post for the support team
+
+No manual action required. If notifications don't appear, see [Troubleshooting: Slack Notifications Not Sent](#slack-notifications-not-sent).
+
 ---
 
 ## Creating a Patch Release
@@ -388,6 +418,25 @@ git push --force-with-lease
    gh release edit 0.27.0 --repo codefresh-io/gitops-runtime-helm --draft=false
    ```
 
+### Slack Notifications Not Sent
+
+**Symptom**: Release published but no Slack notifications appeared
+
+**Check**:
+1. Verify the `release-notification` workflow ran:
+   - Go to Actions tab → "Release Notification" workflow
+   - Check for failed runs
+2. If workflow failed, check for:
+   - Missing `SLACK_BOT_TOKEN` secret
+   - Missing `SLACK_CHANNEL_GITOPS_RUNTIME` or `SLACK_CHANNEL_SUPPORT_ANNOUNCEMENTS` variables
+   - Bot not invited to the channels
+3. Manual fallback - post manually to Slack:
+   ```
+   🚀 GitOps Runtime vX.Y.Z has been released!
+
+   Release notes: https://github.com/codefresh-io/gitops-runtime-helm/releases/tag/X.Y.Z
+   ```
+
 ---
 
 ## Reference
@@ -428,6 +477,7 @@ git push --force-with-lease
 |------|---------|
 | `charts/gitops-runtime/Chart.yaml` | Version, changelog annotations |
 | `charts/gitops-runtime/values.yaml` | Component versions, defaults |
+| `.github/workflows/release-notification.yaml` | Slack release announcements |
 
 ---