fix(ci): create one layer artifact per region & merge (#2095)

* chore(ci): restore layer arn artifact uploads

* chore(ci): step name

* chore(ci): remove artifact name

* chore(ci): remove trailing slash from path

* chore(ci): add comment

Author: dreamorosi

.github/workflows/publish_layer.yml

@@ -94,11 +94,12 @@ jobs:
         uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11  # v4.1.1
         with:
           ref: ${{ github.sha }}
-      - name: Download CDK layer artifact
+      - name: Download CDK layer artifacts
         uses: actions/download-artifact@eaceaf801fd36c7dee90939fad912460b18a1ffe # v4.1.2
         with:
-          name: cdk-layer-stack
-          path: cdk-layer-stack/
+          path: cdk-layer-stack
+          pattern: cdk-layer-stack-* # merge all Layer artifacts created per region earlier (reusable_deploy_layer_stack.yml; step "Save Layer ARN artifact")
+          merge-multiple: true
       - name: Replace layer versions in documentation
         run: |
           ls -la cdk-layer-stack/

.github/workflows/reusable_deploy_layer_stack.yml

@@ -93,10 +93,9 @@ jobs:
         if: ${{ inputs.stage == 'PROD' }}
         uses: actions/upload-artifact@5d5d22a31266ced268874388b861e4b58bb5c2f3 # v4.3.1
         with:
-          name: cdk-layer-stack
+          name: cdk-layer-stack-${{ matrix.region }}
           path: ./cdk-layer-stack/* # NOTE: upload-artifact does not inherit working-directory setting.
           if-no-files-found: error
           retention-days: 1
-          overwrite: true
       - name: CDK deploy canary
         run: npm run cdk -w layers -- deploy --app cdk.out --context region=${{ matrix.region }} 'CanaryStack' --require-approval never --verbose --outputs-file cdk-outputs.json