Fix CI for forks by moving merge queue runs into a separate workflow

.github/workflows/ci-merge-queue.yml

@@ -0,0 +1,93 @@
+# Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+# SPDX-License-Identifier: Apache-2.0
+
+# This workflow runs CI for the GitHub merge queue.
+
+name: Merge Queue CI
+on:
+  merge_group:
+    types: [checks_requested]
+
+# Allow one instance of this workflow per merge
+concurrency:
+  group: ci-merge-queue-yml-${{ github.ref }}
+  cancel-in-progress: true
+
+env:
+  ecr_repository: public.ecr.aws/w0m4q9l7/github-awslabs-smithy-rs-ci
+
+jobs:
+  # This job will, if possible, save a docker login password to the job outputs. The token will
+  # be encrypted with the passphrase stored as a GitHub secret. The login password expires after 12h.
+  # The login password is encrypted with the repo secret DOCKER_LOGIN_TOKEN_PASSPHRASE
+  save-docker-login-token:
+    name: Save a docker login token
+    outputs:
+      docker-login-password: ${{ steps.set-token.outputs.docker-login-password }}
+    permissions:
+      id-token: write
+      contents: read
+    continue-on-error: true
+    runs-on: ubuntu-latest
+    steps:
+    - name: Attempt to load a docker login password
+      uses: aws-actions/configure-aws-credentials@v1-node16
+      with:
+        role-to-assume: ${{ secrets.SMITHY_RS_PUBLIC_ECR_PUSH_ROLE_ARN }}
+        role-session-name: GitHubActions
+        aws-region: us-west-2
+    - name: Save the docker login password to the output
+      id: set-token
+      run: |
+        ENCRYPTED_PAYLOAD=$(
+          gpg --symmetric --batch --passphrase "${{ secrets.DOCKER_LOGIN_TOKEN_PASSPHRASE }}" --output - <(aws ecr-public get-login-password --region us-east-1) | base64 -w0
+        )
+        echo "docker-login-password=$ENCRYPTED_PAYLOAD" >> $GITHUB_OUTPUT
+
+  # This job detects if the PR made changes to build tools. If it did, then it builds a new
+  # build Docker image. Otherwise, it downloads a build image from Public ECR. In both cases,
+  # it uploads the image as a build artifact for other jobs to download and use.
+  acquire-base-image:
+    name: Acquire Base Image
+    needs: save-docker-login-token
+    runs-on: ubuntu-latest
+    env:
+      ENCRYPTED_DOCKER_PASSWORD: ${{ needs.save-docker-login-token.outputs.docker-login-password }}
+      DOCKER_LOGIN_TOKEN_PASSPHRASE: ${{ secrets.DOCKER_LOGIN_TOKEN_PASSPHRASE }}
+    permissions:
+      id-token: write
+      contents: read
+    steps:
+    - uses: actions/checkout@v3
+      with:
+        path: smithy-rs
+    - name: Acquire base image
+      id: acquire
+      env:
+        DOCKER_BUILDKIT: 1
+      run: ./smithy-rs/.github/scripts/acquire-build-image
+    - name: Acquire credentials
+      uses: aws-actions/configure-aws-credentials@v1-node16
+      with:
+        role-to-assume: ${{ secrets.SMITHY_RS_PUBLIC_ECR_PUSH_ROLE_ARN }}
+        role-session-name: GitHubActions
+        aws-region: us-west-2
+    - name: Upload image
+      run: |
+        IMAGE_TAG="$(./smithy-rs/.github/scripts/docker-image-hash)"
+        docker tag "smithy-rs-base-image:${IMAGE_TAG}" "${{ env.ecr_repository }}:${IMAGE_TAG}"
+        aws ecr-public get-login-password --region us-east-1 | docker login --username AWS --password-stdin public.ecr.aws
+        docker push "${{ env.ecr_repository }}:${IMAGE_TAG}"
+
+  # Run shared CI after the Docker build image has either been rebuilt or found in ECR
+  ci:
+    needs:
+    - save-docker-login-token
+    - acquire-base-image
+    if: ${{ github.event.pull_request.head.repo.full_name == 'awslabs/smithy-rs' || toJSON(github.event.merge_group) != '{}' }}
+    uses: ./.github/workflows/ci.yml
+    with:
+      run_sdk_examples: true
+    secrets:
+      ENCRYPTED_DOCKER_PASSWORD: ${{ needs.save-docker-login-token.outputs.docker-login-password }}
+      DOCKER_LOGIN_TOKEN_PASSPHRASE: ${{ secrets.DOCKER_LOGIN_TOKEN_PASSPHRASE }}

.github/workflows/ci-pr.yml

@@ -6,8 +6,6 @@
 name: CI
 on:
   pull_request:
-  merge_group:
-    types: [checks_requested]
 
 # Allow one instance of this workflow per pull request, and cancel older runs when new changes are pushed
 concurrency:
@@ -23,7 +21,7 @@ jobs:
   # The login password is encrypted with the repo secret DOCKER_LOGIN_TOKEN_PASSPHRASE
   save-docker-login-token:
     name: Save a docker login token
-    if: ${{ github.event.pull_request.head.repo.full_name == 'awslabs/smithy-rs' || toJSON(github.event.merge_group) != '{}' }}
+    if: ${{ github.event.pull_request.head.repo.full_name == 'awslabs/smithy-rs' }}
     outputs:
       docker-login-password: ${{ steps.set-token.outputs.docker-login-password }}
     permissions:
@@ -53,7 +51,7 @@ jobs:
   acquire-base-image:
     name: Acquire Base Image
     needs: save-docker-login-token
-    if: ${{ github.event.pull_request.head.repo.full_name == 'awslabs/smithy-rs' || toJSON(github.event.merge_group) != '{}' }}
+    if: ${{ github.event.pull_request.head.repo.full_name == 'awslabs/smithy-rs' }}
     runs-on: ubuntu-latest
     env:
       ENCRYPTED_DOCKER_PASSWORD: ${{ needs.save-docker-login-token.outputs.docker-login-password }}
@@ -88,7 +86,7 @@ jobs:
     needs:
     - save-docker-login-token
     - acquire-base-image
-    if: ${{ github.event.pull_request.head.repo.full_name == 'awslabs/smithy-rs' || toJSON(github.event.merge_group) != '{}' }}
+    if: ${{ github.event.pull_request.head.repo.full_name == 'awslabs/smithy-rs' }}
     uses: ./.github/workflows/ci.yml
     with:
       run_sdk_examples: true