Add Slack alerts for Build workflow failures (#389)

.github/workflows/build.yml

@@ -303,3 +303,52 @@ jobs:
           name: bw-snap-sha256-${{ env._PACKAGE_VERSION }}.txt
           path: ./dist/snap/bw-snap-sha256-${{ env._PACKAGE_VERSION }}.txt
           if-no-files-found: error
+
+
+  check-failures:
+    name: Check for failures
+    if: always()
+    runs-on: ubuntu-20.04
+    needs:
+      - cloc
+      - setup
+      - cli
+      - snap
+    steps:
+      - name: Check if any job failed
+        env:
+          CLOC_STATUS: ${{ needs.cloc.result }}
+          SETUP_STATUS: ${{ needs.setup.result }}
+          CLI_STATUS: ${{ needs.cli.result }}
+          SNAP_STATUS: ${{ needs.snap.result }}
+        run: |
+          if [ "$CLOC_STATUS" = "failure" ]; then
+              exit 1
+          elif [ "$SETUP_STATUS" = "failure" ]; then
+              exit 1
+          elif [ "$CLI_STATUS" = "failure" ]; then
+              exit 1
+          elif [ "$SNAP_STATUS" = "failure" ]; then
+              exit 1
+          fi
+      - name: Login to Azure - Prod Subscription
+        uses: Azure/login@77f1b2e3fb80c0e8645114159d17008b8a2e475a
+        if: failure()
+        with:
+          creds: ${{ secrets.AZURE_PROD_KV_CREDENTIALS }}
+
+      - name: Retrieve secrets
+        id: retrieve-secrets
+        uses: Azure/get-keyvault-secrets@80ccd3fafe5662407cc2e55f202ee34bfff8c403
+        if: failure()
+        with:
+          keyvault: "bitwarden-prod-kv"
+          secrets: "devops-alerts-slack-webhook-url"
+
+      - name: Notify Slack on failure
+        uses: act10ns/slack@e4e71685b9b239384b0f676a63c32367f59c2522  # v1.2.2
+        if: failure()
+        env:
+          SLACK_WEBHOOK_URL: ${{ steps.retrieve-secrets.outputs.devops-alerts-slack-webhook-url }}
+        with:
+          status: ${{ job.status }}