feat: show deployment plan only if it has changed (#61)

Author: lemmih

.github/workflows/deploy.yml

@@ -47,14 +47,23 @@ jobs:
         run: terraform plan -no-color -input=false
         continue-on-error: true
 
-      - name: Update Pull Request
-        uses: mshick/add-pr-comment@v2
-        if: github.event_name == 'pull_request'
+      - name: Find Comment
+        uses: peter-evans/find-comment@v2
+        id: fc
+        with:
+          issue-number: ${{ github.event.pull_request.number }}
+          comment-author: 'github-actions[bot]'
+          body-regex: "^### Snapshot Service Plan"
+
+      # If the new deployment plan contains changes, post it in a comment.
+      - name: Create or update comment
+        uses: peter-evans/create-or-update-comment@v2
+        if: github.event_name == 'pull_request' && !contains(steps.plan.outputs.stdout, 'No changes. Your infrastructure matches the configuration.')
         with:
-          github-token: ${{ secrets.GITHUB_TOKEN }}
-          with:
-          message: |
-            #### Terraform Plan 📖${{ steps.plan.outcome }}
+          comment-id: ${{ steps.fc.outputs.comment-id }}
+          issue-number: ${{ github.event.pull_request.number }}
+          body: |
+            ### Snapshot Service Plan: ${{ steps.plan.outcome }}
 
             <details><summary>Show Plan</summary>
 
@@ -63,7 +72,15 @@ jobs:
             ```
 
             </details>
+          edit-mode: replace
 
+      # If the new deployment plan contains no changes, delete the last posted plan.
+      - name: Delete comment
+        uses: detomarco/[email protected]
+        if: github.event_name == 'pull_request' && contains(steps.plan.outputs.stdout, 'No changes. Your infrastructure matches the configuration.')
+        with:
+          comment-id: ${{ steps.fc.outputs.comment-id }}
+      
       - name: Terraform Plan Status
         if: steps.plan.outcome == 'failure'
         run: exit 1