Continuous Deployment to Kubernetes Engine using Jenkins

This tutorial shows you how to set up a continuous delivery pipeline using Jenkins and GKE, as described in the following diagram.

Objectives

• Understanding a sample application.
• Deploying an application to Kubernetes.
• Uploading code to Cloud Source Repositories.
• Creating deployment pipelines in Jenkins.
• Deploying development environments.
• Deploying a canary release.
• Deploying production environments.

Costs

This tutorial uses billable components of Google Cloud Platform (GCP), including:

• Compute Engine
• Google Kubernetes Engine
• Cloud Build

Use the Pricing Calculator to generate a cost estimate based on your projected usage for this tutorial. New GCP users might be eligible for a free trial.

Before you begin

1. Sign in to your Google Account.

   If you don't already have one, sign up for a new account.

2. Select or create a GCP project.

   Note: If you don't plan to keep the resources you create in this tutorial, create a new project instead of selecting an existing project. After you finish, you can delete the project, removing all resources associated with the project and tutorial.

   Go to the Manage resources page

3. Make sure that billing is enabled for your project.

   Learn how to enable billing

4. Enable the Compute Engine, Kubernetes Engine, and Cloud Build APIs.

   Enable the APIs

Preparing your environment

1. Complete the Setting up Jenkins on GKE tutorial.

2. In Cloud Shell, navigate to the sample application directory.

   cd continuous-deployment-on-kubernetes/sample-app
   

Understanding the application

You'll deploy the sample application, gceme, in your continuous deployment pipeline. The application is written in the Go language, and is located in the repo's sample-app directory. When you run the gceme binary on a Compute Engine instance, the app displays the instance's metadata in an info card.

The application mimics a microservice by supporting two operation modes.

• In backend mode, gceme listens on port 8080 and returns Compute Engine instance metadata in JSON format.

• In frontend mode, gceme queries the backend gceme service, and renders the resulting JSON in the user interface.

  

The frontend and backend modes support two additional URLs.

• /version prints the running version.
• /healthz reports the application's health. In frontend mode, the health displays as OK if the backend is reachable.

Deploying the sample app to Kubernetes

Deploy the gceme frontend and backend to Kubernetes using manifest files that describe the deployment environment. The files use a default image that is updated later in this tutorial.

Deploy the applications into two environments.

• Production. The live site that your users access.

• Canary. A smaller-capacity site that receives a percentage of your user traffic. Use this environment to sanity check your software with live traffic before it's released to the live environment.

First, deploy your application into the production environment to seed the pipeline with working code.

1. Create the Kubernetes namespace to logically isolate the production deployment.

   kubectl create ns production
   

2. Create the canary and production deployments and services.

   kubectl --namespace=production apply -f k8s/production
   kubectl --namespace=production apply -f k8s/canary
   kubectl --namespace=production apply -f k8s/services
   

3. Scale up the production environment frontends.

   kubectl --namespace=production scale deployment gceme-frontend-production --replicas=4
   

4. Retrieve the external IP for the production services. It can take several minutes before you see the load balancer IP address.

   kubectl --namespace=production get service gceme-frontend
   

   When the process completes, an IP address displays in the EXTERNAL-IP column.

   NAME             TYPE           CLUSTER-IP     EXTERNAL-IP    PORT(S)        AGE
   gceme-frontend   LoadBalancer   10.35.254.91   35.196.48.78   80:31088/TCP   1m
   

5. Store the frontend service load balancer IP in an environment variable.

   export FRONTEND_SERVICE_IP=$(kubectl get -o jsonpath="{.status.loadBalancer.ingress[0].ip}"  --namespace=production services gceme-frontend)
   

6. Confirm that both services are working by opening the frontend external IP address in your browser.

7. Open a separate terminal and poll the production endpoint's /version URL so you can observe rolling updates in the next section.

   while true; do curl http://$FRONTEND_SERVICE_IP/version; sleep 1;  done
   

Creating a repository to host the sample app source code

Next, create a copy of the gceme sample app and push it to Cloud Source Repositories.

1. Create the repository in Cloud Source Repositories.

   gcloud source repos create gceme
   

2. Initialize the local Git repository.

   git init
   git config credential.helper gcloud.sh
   export PROJECT_ID=$(gcloud config get-value project)
   git remote add origin https://source.developers.google.com/p/$PROJECT_ID/r/gceme
   

3. Set the username and email address for your Git commits in this repository.

   git config --global user.email "[EMAIL_ADDRESS]"
   

   Replace [EMAIL_ADDRESS] with your Git email address.

   git config --global user.name "[USERNAME]"
   

   Replace [USERNAME] with your Git username.

4. Add, commit, and push the files.

   git add .
   git commit -m "Initial commit"
   git push origin master
   

Creating a pipeline

Use Jenkins to define and run a pipeline for testing, building, and deploying your copy of gceme to your Kubernetes cluster.

Adding your service account credentials

Configure your credentials to allow Jenkins to access the code repository.

1. In the Jenkins user interface, Click Credentials in the left navigation.

2. Click the Jenkins link in the Credentials table.

   

3. Click Global Credentials.

4. Click Add Credentials in the left navigation.

5. Select Google Service Account from metadata from the Kind dropdown.

6. Click OK.

There are now two global credentials. Make a note of second credential's name for use later on in this tutorial.

Creating a Jenkins job

Next, use the Jenkins Pipeline feature to configure the build pipeline. Jenkins Pipeline files are written using a Groovy-like syntax.

Navigate to your Jenkins user interface and follow these steps to configure a Pipeline job.

1. Click the Jenkins link in the top left of the interface.

2. Click the New Item link in the left navigation.

3. Name the project sample-app, then choose the Multibranch Pipeline option, then click OK.

4. On the next page, click Add Source and select git.

5. Paste the HTTPS clone URL of your sample-app repo in Cloud Source Repositories into the Project Repository field. Replace [PROJECT_ID] with your project ID.

   https://source.developers.google.com/p/[PROJECT_ID]/r/gceme
   

6. From the Credentials dropdown, select the name of the credentials you created when adding your service account.

7. In the Scan Multibranch Pipeline section, select the Periodically if not otherwise run box. Set the Interval value to '1 minute'.

8. Click Save.

   

After you complete these steps, a job named "Branch indexing" runs. This meta-job identifies the branches in your repository and ensures changes haven't occurred in existing branches. If you refresh Jenkins, the master branch displays this job.

The first run of the job fails until you make a few code changes in the next step.

Modifying the Pipeline definition

Create a branch for the canary environment, called canary.

git checkout -b canary

The Jenkinsfile container that defines that pipeline is written using the Jenkins Pipeline Groovy syntax. Using a Jenkinsfile allows an entire build pipeline to be expressed in a single file that lives alongside your source code. Pipelines support powerful features like parallelization and requiring manual user approval.

Modify the Jenkinsfile so that it contains your project ID on line 1.

Deploying a canary release

Now that your pipeline is configured properly, it's time to make a change to the gceme application and let your pipeline test, package, and deploy it.

The canary environment is set up as a canary release. As such, your change is released to a small percentage of the pods behind the production load balancer. You accomplish this in Kubernetes by maintaining multiple deployments that share the same labels. For this application, the gceme-frontend services load balance across all pods that have the labels app: gceme and role: frontend. The k8s/frontend-canary.yaml canary manifest file sets the replicas to 1 and includes labels required for the gceme-frontend service.

Currently, you have 1 out of 5 of the frontend pods running the canary code while the other 4 are running the production code. This helps ensure that the canary code doesn't negatively affect users before rolling out to your full fleet of pods.

1. Open html.go and replace the two instances of blue with orange.

2. Open main.go and change the version number from 1.0.0 to 2.0.0.

    const version string = "2.0.0"
   

3. Next, add and commit those files to your local repository.

    git add Jenkinsfile html.go main.go
    git commit -m "Version 2"
   

4. Finally, push your changes to the remote Git server.

    git push origin canary
   

5. After the change is pushed to the Git repository, navigate to the Jenkins user interface where you can see that your build started.

   

6. After the build is running, click the down arrow next to the build in the left navigation and select Console Output.

   

7. Track the output of the build for a few minutes and watch for the kubectl --namespace=production apply... messages to begin. When they start, check back on the terminal that was polling the production /version URL and observe begin to change in some of the requests. You have now rolled out that change to a subset of users.

8. After the change is deployed to the canary environment, you can continue to roll it out to the rest of your users by merging the code with the master branch and pushing that to the Git server.

   git checkout master
   git merge canary
   git push origin master
   

9. In approximately 1 minute, the master job in the sample-app folder kicks off.

   

10. Clicking on the master link shows you the stages of your pipeline, as well as pass/fail information and timing characteristics.

    

11. Poll the production URL to verify that the new version 2.0.0 has been rolled out and is serving requests from all users.

    export FRONTEND_SERVICE_IP=$(kubectl get -o jsonpath="{.status.loadBalancer.ingress[0].ip}" --namespace=production services gceme-frontend)
    while true; do curl http://$FRONTEND_SERVICE_IP/version; sleep 1;  done
    

You can look at the Jenkinsfile in the project to see the workflow.

Deploying a development branch

Sometimes you need to work with non-trivial changes that can't be pushed directly to the canary environment. A development branch is a set of environments your developers use to test their code changes before submitting them for integration into the live site. These environments are a scaled-down version of your application, but are deployed using the same mechanisms as the live environment.

To create a development environment from a feature branch, you can push the branch to the Git server and let Jenkins deploy your environment. In a development scenario, you wouldn't use a public-facing load balancer. To help secure your application you can use kubectl proxy. The proxy authenticates itself with the Kubernetes API, and proxies requests from your local machine to the service in the cluster without exposing your service to the Internet.

1. Create another branch and push it to the Git server.

   git checkout -b new-feature
   git push origin new-feature
   

A new job is created and your development environment is in the process of being created. At the bottom of the console output of the job are instructions for accessing your environment.

1. Start the proxy in the background.

   kubectl proxy &
   

2. Verify that your application is accessible by using localhost.

   curl http://localhost:8001/api/v1/proxy/namespaces/new-feature/services/gceme-frontend:80/
   

3. You can now push code to this branch to update your development environment. When you are done, merge your branch back into canary to deploy that code to the canary environment.

   git checkout canary
   git merge new-feature
   git push origin canary
   

4. When you are confident that your code won't cause problems in the production environment, merge from the canary branch to the master branch to kick off the deployment.

   git checkout master
   git merge canary
   git push origin master
   

5. When you are done with the development branch, delete it from the server and delete the environment from your Kubernetes cluster.

   git push origin :new-feature
   kubectl delete ns new-feature
   

Cleaning up

To avoid incurring charges to your Google Cloud Platform account for the resources used in this tutorial:

Deleting the project

The easiest way to eliminate billing is to delete the project you created for the tutorial.

To delete the project:

Caution: Deleting a project has the following effects:

• Everything in the project is deleted. If you used an existing project for this tutorial, when you delete it, you also delete any other work you've done in the project.
• Custom project IDs are lost. When you created this project, you might have created a custom project ID that you want to use in the future. To preserve the URLs that use the project ID, such as an appspot.com URL, delete selected resources inside the project instead of deleting the whole project.

If you plan to explore multiple tutorials and quickstarts, reusing projects can help you avoid exceeding project quota limits.

1. In the GCP Console, go to the Projects page.

   Go to the Projects page

2. In the project list, select the project you want to delete and click Delete.
3. In the dialog, type the project ID, and then click Shut down to delete the project.

What's next

• Learn more about Jenkins on GKE best practices.

• See the setting up Jenkins on GKE tutorial.

• Learn about how to configure Jenkins for GKE.

• Try out other Google Cloud Platform features for yourself. Have a look at our tutorials.