Deploy / destroy review apps with CodeBuild

Instead of running Terraform directly in the GitHub Actions runners, we
now trigger AWS CodeBuild projects to handle the deployment and
destruction of review apps. This means that the repository no longer
needs extensive AWS permissions in GitHub Actions, and the actual available
AWS operations are limited.

Author: whi-tw

.github/workflows/review_apps_on_pr_change.yml

@@ -1,18 +1,15 @@
 name: "Review apps: on PR change"
 on:
   pull_request:
-    # being explicit about what to trigger on.
-    # matches the docs for the default types
-    # https://docs.github.com/en/actions/writing-workflows/choosing-when-your-workflow-runs/events-that-trigger-workflows#pull_request
     types: [opened, reopened, synchronize]
 
 concurrency:
   group: "review-apps-forms-admin-pr-${{ github.event.pull_request.number }}"
   cancel-in-progress: false
+
 jobs:
   update-review-app:
     runs-on: ubuntu-24.04-arm
-
     permissions:
       id-token: write
       contents: read
@@ -24,69 +21,68 @@ jobs:
         with:
           role-to-assume: arn:aws:iam::842676007477:role/review-github-actions-forms-admin
           aws-region: eu-west-2
-      - name: Generate container image URI
-        run: |
-          echo "CONTAINER_IMAGE_URI=842676007477.dkr.ecr.eu-west-2.amazonaws.com/forms-admin:pr-${{github.event.pull_request.number}}-${{github.event.pull_request.head.sha}}-$(date +%s)" >> "$GITHUB_ENV"
 
       - name: Checkout code
         uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
 
-      - name: Build container
+      - name: Generate container image URI
         run: |
-          docker build \
-            --tag "${{env.CONTAINER_IMAGE_URI}}" \
-            .
+          echo "CONTAINER_IMAGE_URI=842676007477.dkr.ecr.eu-west-2.amazonaws.com/forms-admin:pr-${{github.event.pull_request.number}}-${{github.event.pull_request.head.sha}}-$(date +%s)" >> "$GITHUB_ENV"
+
+      - name: Build container
+        run: docker build --tag "${{env.CONTAINER_IMAGE_URI}}" .
 
       - name: Push container
-        id: build-container
         run: |
           aws ecr get-login-password --region eu-west-2 \
           | docker login --username AWS --password-stdin 842676007477.dkr.ecr.eu-west-2.amazonaws.com
-
-          echo "Pushing container image"
-          echo "${{env.CONTAINER_IMAGE_URI}}"
-
           docker push "${CONTAINER_IMAGE_URI}"
 
-      - name: Determine Terraform version
-        id: terraform-version
-        run: |
-          cat .review_apps/.terraform-version | xargs printf "TF_VERSION=%s" >> "$GITHUB_OUTPUT"
-
-      - uses: hashicorp/setup-terraform@b9cd54a3c349d3f38e8881555d616ced269862dd # v3.1.2
+      - name: Deploy review app via CodeBuild
+        id: codebuild
+        uses: aws-actions/aws-codebuild-run-build@4d15a47425739ac2296ba5e7eee3bdd4bfbdd767 # v1.0.18
         with:
-          terraform_version: ${{steps.terraform-version.outputs.TF_VERSION}}
+          project-name: review-forms-admin-deploy
+          env-vars-for-codebuild: |
+            PR_NUMBER,
+            CONTAINER_IMAGE
+        env:
+          PR_NUMBER: ${{ github.event.pull_request.number }}
+          CONTAINER_IMAGE: ${{ env.CONTAINER_IMAGE_URI }}
 
-      - name: Deploy review app
-        id: deploy
+      - name: Fetch terraform outputs
+        id: outputs
         run: |
-          cd .review_apps/
+          # Extract build UUID from ARN (format: arn:aws:codebuild:region:account:build/project:uuid)
+          BUILD_ID="${{ steps.codebuild.outputs.aws-build-id }}"
+          BUILD_UUID="${BUILD_ID##*:}"
 
-          terraform init -backend-config="key=review-apps/forms-admin/pr-${{github.event.pull_request.number}}.tfstate"
+          # Download artifact
+          aws s3 cp "s3://forms-review-codebuild-artifacts/${BUILD_UUID}/review-forms-admin-deploy/outputs.json" outputs.json
 
-          terraform apply \
-            -var "pull_request_number=${{github.event.pull_request.number}}" \
-            -var "forms_admin_container_image=${{env.CONTAINER_IMAGE_URI}}" \
-            -no-color \
-            -auto-approve
+          # Parse outputs
+          {
+            echo "REVIEW_APP_URL=$(jq -r '.review_app_url.value' outputs.json)"
+            echo "ECS_CLUSTER_ID=$(jq -r '.review_app_ecs_cluster_id.value' outputs.json)"
+            echo "ECS_SERVICE_NAME=$(jq -r '.review_app_ecs_service_name.value' outputs.json)"
+          } >> "$GITHUB_OUTPUT"
 
-          echo "REVIEW_APP_URL=$(terraform output -raw review_app_url)" >> "$GITHUB_OUTPUT"
-          echo "ECS_CLUSTER_ID=$(terraform output -raw review_app_ecs_cluster_id)" >> "$GITHUB_OUTPUT"
-          echo "ECS_SERVICE_NAME=$(terraform output -raw review_app_ecs_service_name)" >> "$GITHUB_OUTPUT"
+          # Clean up artifact
+          aws s3 rm "s3://forms-review-codebuild-artifacts/${BUILD_UUID}/review-forms-admin-deploy/outputs.json"
 
       - name: Wait for AWS ECS deployments to finish
         run: |
           aws ecs wait services-stable \
-            --cluster "${{steps.deploy.outputs.ECS_CLUSTER_ID}}" \
-            --services "${{steps.deploy.outputs.ECS_SERVICE_NAME}}"
+            --cluster "${{ steps.outputs.outputs.ECS_CLUSTER_ID }}" \
+            --services "${{ steps.outputs.outputs.ECS_SERVICE_NAME }}"
 
       - name: Comment on PR
         env:
           COMMENT_MARKER: <!-- review apps on pr change -->
           GH_TOKEN: ${{ github.token }}
         run: |
           cat <<EOF > "${{runner.temp}}/pr-comment.md"
-          :tada: A review copy of this PR has been deployed! You can reach it at: ${{steps.deploy.outputs.REVIEW_APP_URL}}
+          :tada: A review copy of this PR has been deployed! You can reach it at: ${{steps.outputs.outputs.REVIEW_APP_URL}}
 
           It may take 5 minutes or so for the application to be fully deployed and working. If it still isn't ready
           after 5 minutes, there may be something wrong with the ECS task. You will need to go to the integration AWS account
@@ -97,6 +93,7 @@ jobs:
           $COMMENT_MARKER
           EOF
 
+          # shellcheck disable=SC2016
           old_comment_ids=$(gh api "repos/{owner}/{repo}/issues/${{github.event.pull_request.number}}/comments" --jq 'map(select((.user.login == "github-actions[bot]") and (.body | endswith($ENV.COMMENT_MARKER + "\n")))) | .[].id')
           for comment_id in $old_comment_ids; do
             gh api -X DELETE "repos/{owner}/{repo}/issues/comments/${comment_id}"

.github/workflows/review_apps_on_pr_close.yml

@@ -1,14 +1,12 @@
 name: "Review apps: on PR close"
 on:
   pull_request:
-    # only run when a PR is closed or merged
     types: [closed]
 
 concurrency:
   group: "review-apps-forms-admin-pr-${{ github.event.pull_request.number }}"
   cancel-in-progress: false
-env:
-  IMAGE_TAG: "842676007477.dkr.ecr.eu-west-2.amazonaws.com/forms-admin:pr-${{github.event.pull_request.number}}-${{github.event.pull_request.head.ref}}"
+
 jobs:
   delete-review-app:
     runs-on: ubuntu-24.04-arm
@@ -22,25 +20,12 @@ jobs:
         with:
           role-to-assume: arn:aws:iam::842676007477:role/review-github-actions-forms-admin
           aws-region: eu-west-2
-      - name: Checkout code
-        uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
-
-      - name: Determine Terraform version
-        id: terraform-version
-        run: |
-          cat .review_apps/.terraform-version | xargs printf "TF_VERSION=%s" >> "$GITHUB_OUTPUT"
 
-      - uses: hashicorp/setup-terraform@b9cd54a3c349d3f38e8881555d616ced269862dd # v3.1.2
+      - name: Destroy review app via CodeBuild
+        uses: aws-actions/aws-codebuild-run-build@4d15a47425739ac2296ba5e7eee3bdd4bfbdd767 # v1.0.18
         with:
-          terraform_version: ${{steps.terraform-version.outputs.TF_VERSION}}
-
-      - name: Delete review app
-        run: |
-          cd .review_apps/
-
-          terraform init -backend-config="key=review-apps/forms-admin/pr-${{github.event.pull_request.number}}.tfstate"
-          terraform destroy \
-            -var "pull_request_number=${{github.event.pull_request.number}}" \
-            -var "forms_admin_container_image=${{env.IMAGE_TAG}}" \
-            -no-color \
-            -auto-approve
+          project-name: review-forms-admin-destroy
+          env-vars-for-codebuild: |
+            PR_NUMBER
+        env:
+          PR_NUMBER: ${{ github.event.pull_request.number }}