Status code can be used.

README.md

@@ -83,6 +83,10 @@ jobs:
 - `working_dir` AWS CDK working directory. (default: '.')
 - `actions_comment` Whether or not to comment on pull requests. (default: true)
 
+## Outputs
+
+- `status_code` Returned status code.
+
 ## ENV
 
 - `AWS_ACCESS_KEY_ID` **Required**

action.yml

@@ -20,6 +20,9 @@ inputs:
   actions_comment:
     description: 'Whether or not to comment on pull requests.'
     default: true
+outputs:
+  status_code:
+    description: 'Returned status code.'
 runs:
   using: 'docker'
   image: './Dockerfile'

entrypoint.sh

@@ -45,6 +45,7 @@ function runCdk(){
 	echo "Run cdk ${INPUT_CDK_SUBCOMMAND} ${*} ${INPUT_CDK_STACK}"
 	output=$(cdk ${INPUT_CDK_SUBCOMMAND} ${*} ${INPUT_CDK_STACK} 2>&1)
 	exitCode=${?}
+	echo ::set-output name=status_code::${exitCode}
 	echo "${output}"
 
 	commentStatus="Failed"

examples/notify_difference_to_slack.yaml

@@ -0,0 +1,29 @@
+# If Stack has difference, notify to slack
+
+on: [pull_request]
+
+jobs:
+  aws_cdk:
+    runs-on: ubuntu-latest
+    steps:
+      - name: cdk diff
+        id: diff
+        uses: youyo/aws-cdk-github-actions@master
+        with:
+          cdk_subcommand: 'diff'
+          actions_comment: true
+        env:
+          AWS_ACCESS_KEY_ID: ${{ secrets.AWS_ACCESS_KEY_ID }}
+          AWS_SECRET_ACCESS_KEY: ${{ secrets.AWS_SECRET_ACCESS_KEY }}
+          AWS_DEFAULT_REGION: 'ap-northeast-1'
+
+      # https://github.com/marketplace/actions/action-slack
+      - name: notify slack
+        uses: 8398a7/action-slack@v2
+        with:
+          status: ${{ job.status }}
+          author_name: GitHubActions
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          SLACK_WEBHOOK_URL: ${{ secrets.SLACK_WEBHOOK_URL }}
+        if: ${{ steps.diff.outputs.status_code }} == 1