Update existing message

.github/workflows/release-notify.yml

@@ -61,7 +61,7 @@ jobs:
               elements: [
                 {
                   type: "mrkdwn",
-                  // text: `Release PR: <${urlForPr(context.payload.number)}|${urlForPr(context.payload.number)}>`,
+                  // text: `Release PR: ${urlForPr(context.payload.number)`,
                   // TODO: revert back
                   text: `Release PR: <${urlForPr(5202)}|${urlForPr(5202)}>`,
                 },
@@ -77,11 +77,21 @@ jobs:
             }
 
             blocks.push({
+              "type": "divider"
+            }, {
               type: "section",
               text: {
                 type: "mrkdwn",
                 text: messageBody,
               },
+            }, {
+              "type": "divider"
+            }, {
+              type: "context",
+              elements: [{
+                type: "plain_text",
+                text: `Updated at <!date^${Date.now() / 1000}^{date_num} {time_secs}|${new Date().toISOString()}>`,
+              }],
             })
 
             const slackMessage = {
@@ -94,9 +104,34 @@ jobs:
 
             return JSON.stringify(slackMessage)
 
+      - uses: actions/cache/restore@v3
+        with:
+          path: release-notify.json
+          key: release-notify-${{ github.event.number }}.json
+
+      - id: message-id
+        run: |
+          if [ -f release-notify.json ]; then
+            UPDATE_TS=$(cat release-notify.json | jq --raw-output '.ts')
+          else
+            UPDATE_TS=""
+          fi
+
+          echo "update-ts=${UPDATE_TS}" >> $GITHUB_OUTPUT
+
       - uses: slackapi/slack-github-action@v1
+        id: slack
         env:
           SLACK_BOT_TOKEN: ${{ secrets.SLACK_BOT_TOKEN }}
         with:
           channel-id: "C05QQ9J1BRC" # #test-release-notifications
+          update-ts: ${{ steps.message-id.outputs.update-ts }}
           payload: ${{ steps.commitlist.outputs.result }}
+
+      - run: |
+          echo '{"ts": "${{ steps.slack.outputs.ts }}"}' > release-notify.json
+
+      - uses: actions/cache/save@v3
+        with:
+          path: release-notify.json
+          key: release-notify-${{ github.event.number }}.json