Update PR comments in place (#4620)

* Update PR comments in place

Currently, we post a new comment for each change, which is just spam for PRs
with many iterations.

* Pin actions by hash

Author: pquentin

.github/validate-pr/index.js

@@ -141,12 +141,10 @@ async function run() {
     }
     comment += `\nYou can validate ${table.length === 1 ? 'this' : 'these'} API${table.length === 1 ? '' : 's'} yourself by using the ${tick}make validate${tick} target.\n`
 
-    await octokit.rest.issues.createComment({
-      owner: 'elastic',
-      repo: 'elasticsearch-specification',
-      issue_number: context.payload.pull_request.number,
-      body: comment
-    })
+    core.setOutput('has_results', 'true')
+    core.setOutput('comment_body', comment)
+  } else {
+    core.setOutput('has_results', 'false')
   }
 
   core.info('Done!')

.github/workflows/validate-pr.yml

@@ -63,15 +63,25 @@ jobs:
         env:
           GCS_CREDENTIALS: ${{ secrets.GCS_CREDENTIALS }}
 
-      - name: Remove previous comment
-        uses: maheshrayas/action-pr-comment-delete@v1
-        with:
-          github_token: ${{ secrets.GITHUB_TOKEN }}
-          org: elastic
-          repo: elasticsearch-specification
-          user: github-actions[bot]
-          issue: ${{ github.event.number }}
-
       - name: Run validation
+        id: validation
         working-directory: ./elasticsearch-specification
         run: node .github/validate-pr --token ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Find existing comment
+        uses: peter-evans/find-comment@3eae4d37986fb5a8592848f6a574fdf654e61f9e # v3.1.0
+        id: find-comment
+        with:
+          issue-number: ${{ github.event.pull_request.number }}
+          comment-author: 'github-actions[bot]'
+          body-includes: 'Following you can find the validation results'
+
+      - name: Create or update comment
+        if: steps.validation.outputs.has_results == 'true'
+        uses: peter-evans/create-or-update-comment@71345be0265236311c031f5c7866368bd1eff043 # v4.0.0
+        with:
+          token: ${{ secrets.GITHUB_TOKEN }}
+          comment-id: ${{ steps.find-comment.outputs.comment-id }}
+          issue-number: ${{ github.event.pull_request.number }}
+          body: ${{ steps.validation.outputs.comment_body }}
+          edit-mode: replace