Add a workflow to schedule an upgrade test (#260)

Call the test-upgrade workflow weekly on a Thursday and
post to Slack if it is unsuccessful.

Author: m-bull

.github/workflows/schedule-upgrade.yml

@@ -0,0 +1,39 @@
+---
+name: Scheduled upgrade
+
+permissions:
+  contents: read
+  packages: write
+  id-token: write
+
+on:
+  # Run weekly on a Thursday at 6am
+  schedule:
+    - cron: "0 6 * * 4"
+
+jobs:
+  test_upgrade:
+    runs-on: ubuntu-latest
+    if: github.repository == 'azimuth-cloud/azimuth-config'
+    steps:
+      - name: Find latest tagged release
+        id: get-tag
+        run: >-
+          echo "latest=$(gh release view --json tagName --jq .tagName)" >> "$GITHUB_OUTPUT"
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Run upgrade workflow
+        uses: ./.github/workflows/test-upgrade.yml
+        with:
+          from-ref: ${{ steps.get-tag.outputs.latest }}
+          to-ref: "devel"
+
+      - name: Send message to Slack
+        uses: slackapi/slack-github-action@v2.1.1
+        with:
+          webhook: "${{ secrets.SLACK_WEBHOOK_URL }}"
+          webhook-type: incoming-webook
+          payload: |
+            text: ":siren: Scheduled Azimuth upgrade test failed\n"${{ github.server_url }}/${{ github.repository }}/actions/runs/${{ github.run_id }}""
+        if: ${{ failure() }}

.github/workflows/test-upgrade.yml

@@ -9,6 +9,19 @@ permissions:
   id-token: write
 
 on:
+  # Allow to be called by other workflows
+  workflow_call:
+    inputs:
+      from-ref:
+        description: >-
+          The git ref to use for the initial deployment.
+        type: string
+      to-ref:
+        description: >-
+          The git ref to test an upgrade to.
+        type: string
+        default: devel
+
   # Allow manual execution on any branch
   workflow_dispatch:
     # checkov:skip=CKV_GHA_7: "The build output cannot be affected by user parameters other than the build entry point and the top-level source location. GitHub Actions workflow_dispatch inputs MUST be empty. "