partD-ci-pr.md

Part D - Creating a Pull Request

Now that we've tested the new frontend feature locally using the dev cluster, we are ready to put out a Pull Request in the cymbalbank-app-source repository. We will also explore how to stage a pull request's code on the staging GKE cluster, using Cloud Build and the skaffold.yaml file we used in part C.

1. View the Cloud Build pipeline for Pull Requests to the app source repo.

Run these commands from the cymbalbank-app-source root directory:

cp ../cloudbuild-ci-pr.yaml . 
cat cloudbuild-ci-pr.yaml

Expected output:

steps: 
- name: 'gcr.io/google-samples/intro-to-krm/skaffold-mvn:latest'
  id: Deploy to Staging Cluster 
  entrypoint: /bin/sh
  args:
  - '-c'
  - |
    git clone "https://github.com/$$GITHUB_USERNAME/cymbalbank-app-config"
    gcloud container clusters get-credentials ${_CLUSTER_NAME} --zone ${_CLUSTER_ZONE} --project ${PROJECT_ID} 
    skaffold run --profile=staging --default-repo="gcr.io/${PROJECT_ID}/cymbal-bank/${BRANCH_NAME}" --status-check --tail=false --force=true
  secretEnv: ['GITHUB_USERNAME']
substitutions:
  _CLUSTER_NAME: 'cymbal-staging'
  _CLUSTER_ZONE: 'us-central1-a'
availableSecrets:
  secretManager:
  - versionName: projects/${PROJECT_ID}/secrets/github-username/versions/latest
    env: 'GITHUB_USERNAME'
timeout: '1200s' #timeout - 20 minutes
options:
  machineType: 'E2_HIGHCPU_8'

This Cloud Build pipeline is designed to run on open Pull Requests in the cymbalbank-app-source repo. This means that when the build pipeline runs, it will run out of the cymbalbank-app-source directory, at the branch corresponding to the pull request - meaning, the build already will have your frontend banner code.

This build has one step, and runs from a custom skaffold-mvn container, which is just an environment with skaffold, Maven, and kustomize pre-installed. (Maven is needed to build the Java images.) This build does the following:

1. Clones the app config YAML repo into the source repo, like we did locally in Part C.
2. Connects to the GKE staging cluster we created during setup.
3. Uses skaffold run to build and deploy the pull request code to the staging GKE cluster. This skaffold command uses the --status-check flag to ensure that all the pods are running before completing successfully.
4. Waits for the pods to be ready.

Also note how Cloud Build gets the name of the cymbalbank-app-config repo from the GITHUB_USERNAME secret that Terraform added to Secret Manager in Part 1. You can see the Secret Manager secrets for your project in the Google Cloud Console.

Note - this is a basic pull request pipeline. In a real use case, you'd likely run different tests, like linters, unit tests, and integration tests, before staging the code. Also, in a real use case a repo will likely have multiple PRs open at once, and with this build as-is, different PRs would clobber each other because they're trying to deploy the same services to the same namespaces. The way to get around this would be adding a namespaces suffix like frontend-pr1 -- or deploying all the services into the same namespace, eg. pr1.

2. Create the Continuous Integration - PR trigger.

We want Cloud Build to run this build pipeline on every commit to open Github pull requests targeted at the main branch.

Navigate to Cloud Build in the console, then click Triggers. Click Create Trigger.

From the Create Trigger menu, set the fields as follows:

• Name: continuous-integration-pr
• Event: Pull Request
• Repository: <github-username>/cymbalbank-app-source
• Base branch: ^main$
• Configuration: Cloud Build configuration - /cloudbuild-ci-pr.yaml
• Click Create.

3. Return to your terminal, and push your local frontend-banner branch to remote.

git add .
git commit -m "Add frontend banner, PR CI pipeline" 
git push origin frontend-banner

Note - you may see a warning that you've added another repo (cymbalbank-app-config) as an "embedded repo" - this is okay, you can ignore the warning.

warning: adding embedded git repository: cymbalbank-app-config
hint: You've added another git repository inside your current repository.
hint: Clones of the outer repository will not contain the contents of
hint: the embedded repository and will not know how to obtain it.
hint: If you meant to add a submodule, use:

4. Navigate to Github > cymbalbank-app-source and open a pull request in your frontend-banner branch.

This will trigger the cloudbuild-ci-pr.yaml Cloud Build pipeline.

5. Navigate to Cloud Build: History. Watch the Continuous Integration - Pull Request pipeline run.

Note - it may take 5-10 minutes for this pipeline to complete.

6. View the frontend banner in staging.

kubectx cymbal-staging
kubectl get svc frontend -n frontend

Now let's pretend that your pull request was reviewed by a developer teammate, and you're ready to merge the pull request and get your code into production.

Continue to Part E - Merging Your Pull Request.