Deploy / destroy review apps with CodeBuild

whi-tw · whi-tw · commit 26ffaa2316c8 · 2026-01-23T16:20:01.000Z
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.
diff --git a/.github/workflows/review_apps_on_pr_change.yml b/.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-runner-pr-${{ github.event.pull_request.number }}"
   cancel-in-progress: false
+
 jobs:
   update-review-app:
     runs-on: ubuntu-24.04-arm
-
     permissions:
       id-token: write
       contents: read
@@ -24,63 +21,61 @@ jobs:
         with:
           role-to-assume: arn:aws:iam::842676007477:role/review-github-actions-forms-runner
           aws-region: eu-west-2
-      - name: Generate container image URI
-        run: |
-          echo "CONTAINER_IMAGE_URI=842676007477.dkr.ecr.eu-west-2.amazonaws.com/forms-runner:pr-${{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 "${{env.CONTAINER_IMAGE_URI}}" \
-            .
+          echo "CONTAINER_IMAGE_URI=842676007477.dkr.ecr.eu-west-2.amazonaws.com/forms-runner:pr-${{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: |
-          echo "TF_VERSION=$(< .review_apps/.terraform-version)" >> "$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-runner-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-runner/pr-${{github.event.pull_request.number}}.tfstate"
+          # Download artifact
+          aws s3 cp "s3://forms-review-codebuild-artifacts/${BUILD_UUID}/review-forms-runner-deploy/outputs.json" outputs.json
 
-          terraform apply \
-            -var "pull_request_number=${{github.event.pull_request.number}}" \
-            -var "forms_runner_container_image=${{env.CONTAINER_IMAGE_URI}}" \
-            -no-color \
-            -auto-approve
+          # Parse outputs
+          {
+            echo "REVIEW_APP_URL=$(jq -r '.review_app_url.value' outputs.json)"
+            echo "ADMIN_APP_URL=$(jq -r '.admin_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"
 
-            # shellcheck disable=SC2129 # SC2129 is "mainly a stylistic issue" and it breaks our flow
-            echo "REVIEW_APP_URL=$(terraform output -raw review_app_url)" >> "$GITHUB_OUTPUT"
-            echo "ADMIN_APP_URL=$(terraform output -raw admin_app_url)" >> "$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-runner-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:
@@ -90,8 +85,8 @@ jobs:
           cat <<EOF > "${{runner.temp}}/pr-comment.md"
           :tada: A review copy of this PR has been deployed! It is made of up two components
 
-          1. [A review copy of forms-runner](${{steps.deploy.outputs.REVIEW_APP_URL}})
-          2. [A production copy of forms-admin](${{steps.deploy.outputs.ADMIN_APP_URL}})
+          1. [A review copy of forms-runner](${{steps.outputs.outputs.REVIEW_APP_URL}})
+          2. [A production copy of forms-admin](${{steps.outputs.outputs.ADMIN_APP_URL}})
 
           > [!IMPORTANT]
           > Not all of the functionality of forms-runner is present in review apps.
@@ -109,9 +104,7 @@ jobs:
           $COMMENT_MARKER
           EOF
 
-          # shellcheck disable=SC2016
-          # `jq` uses single-quote characters on Unix shells
-          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($ENV.COMMENT_MARKER + "\n")))) | .[].id')
+          old_comment_ids=$(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}"
           done
diff --git a/.github/workflows/review_apps_on_pr_close.yml b/.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-runner-pr-${{ github.event.pull_request.number }}"
   cancel-in-progress: false
-env:
-  IMAGE_TAG: "842676007477.dkr.ecr.eu-west-2.amazonaws.com/forms-runner:pr-${{github.event.pull_request.number}}-${{github.event.pull_request.head.ref}}"
+
 jobs:
   delete-review-app:
     runs-on: ubuntu-24.04-arm
@@ -22,25 +20,12 @@ jobs:
         with:
           role-to-assume: arn:aws:iam::842676007477:role/review-github-actions-forms-runner
           aws-region: eu-west-2
-      - name: Checkout code
-        uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
-
-      - name: Determine Terraform version
-        id: terraform-version
-        run: |
-          echo "TF_VERSION=$(< .review_apps/.terraform-version)" >> "$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: ${{steps.terraform-version.outputs.TF_VERSION}}
-
-      - name: Delete review app
-        run: |
-          cd .review_apps/
-
-          terraform init -backend-config="key=review-apps/forms-runner/pr-${{github.event.pull_request.number}}.tfstate"
-          terraform destroy \
-            -var "pull_request_number=${{github.event.pull_request.number}}" \
-            -var "forms_runner_container_image=${{env.IMAGE_TAG}}" \
-            -no-color \
-            -auto-approve
+          project-name: review-forms-runner-destroy
+          env-vars-for-codebuild: |
+            PR_NUMBER
+        env:
+          PR_NUMBER: ${{ github.event.pull_request.number }}
