Kubernetes Application: CI/CD pipeline - Part I

Overview

Teaching: 0 min
Exercises: 0 min

Questions

Objectives

• Being able to deploy a Jenkins server inside Kubernetes and integrate with GitHub for automated building/testing.

1. Preparation: individual!

• Each student should launch an experiment of their own.
• Visit Dr. Ngo’s Kubernetes-Jenkins branch and create a copy of this branch in your GitHub CloudLab profile repository.
• You can overwrite the existing main branch, or, even better, create a new branch.
• Once the experiment is fully deployed, and all Startup Finished running:
• SSH into the head node and run the followings

$ cd
$ bash /local/repository/launch_network.sh
$ kubectl get nodes

2. Introduction to Jenkins

• Jenkins
• Open-source automation server that allows continuous integration:
  • Recognized whenever source code is changed and/or updated.
  • Automatic building and testing of updated codes.

3. Deploy Jenkins on Kubernetes

• SSH to the headnode of your Kubernetes cluster.

$ kubectl create namespace jenkins
$ kubectl create -f /local/repository/jenkins.yaml --namespace jenkins
$ kubectl get pods -n jenkins

• Repeat the kubectl get pods -n command a few time until you see that the jenkins pod is up and running.

• What did we just deploy: jenkins.yaml.
  • Kubernetes’ deployment template.
  • spec.replicas: 1
  • spec.containers: linhbngo/jenkins-gcc:latest
  • spec.containers.ports: http-port:8000 and jnlp-port:50000
  • …
• Next, run the commands to create Service.
  • A Service is an abstraction that defines a logical set of Pods and a policy by which to access them.
  • The set of pods targeted by a service is determined by a selector.
  • It allows the decoupling of the microservices provided by the pods and the actual pods themselves (which could be created and destroyed as needed).
• The service file for the Jenkins’ pod.

$ kubectl create -f /local/repository/jenkins-service.yaml --namespace jenkins
$ kubectl get services --namespace jenkins

$ kubectl get nodes -o wide

• Grab one of the values of INTERNAL-IP, open a browser and go to INTERNAL-IP:30000

• To find the default password:
  • Write down the NAME value from the first command and use that for the second command.

$ kubectl get pods -n jenkins
$ kubectl logs jenkins-794699f9bc-45tkq -n jenkins

• Copy and paste the initial admin password to the Jenkins’ page and hit Continue.

4. Configure Jenkins

• Click on Install selected plugins

• You can either try to create the first admin user or Skip and continue as admin.

• Click Save and Finish, then Start using Jenkins

5. Integrate Git and Jenkins

• Create a new public GitHub repository named hello with the contents similar to this repository
• In your hello repo, go to Settings/Webhooks and add a new webhook with the settings similar to the screenshot.
  • NOTE: The Payload URL should be YOUR jenkin server URL.
  • Click Add webhook when done.

• On your Jenkins dashboard, select New Item, then setup the new project with the settings similar to the screenshot below. Clicl OK when done.

• Click Source Code Management:

• Click Build Triggers and select GitHub hook trigger for GITScm polling.
• Click Build/Add build step and select Execute shell.

• Enter make in the Command box, then click Save.

• Make an edit to your C file in the hello repo and observe how the jenkins server launches a build.

• Explore the interface to learn more about the details of the build.
• Try to push an incorrect edit to the C file and see how the Jenkins server update the build.

6. Setup Jenkins agents to run on the Kubernetes cluster

• Reminder: If you are launching a new experiment

$ bash /local/repository/launch_network.sh

• Expand NodePort range by editing /etc/kubernetes/manifests/kube-apiserver.yaml and add the following line:
  • service-node-port-range=30000-50000

• sa stands for service account.

$ kubectl create namespace jenkins
$ kubectl create clusterrolebinding permissive-binding --clusterrole=cluster-admin --user=admin --user=kubelet --group=system:serviceaccounts
$ kubectl -n kube-system create sa jenkins
$ kubectl create clusterrolebinding jenkins --clusterrole cluster-admin --serviceaccount=jenkins:jenkins
$ kubectl create -f /local/repository/jenkins.yaml --namespace jenkins
$ kubectl create -f /local/repository/jenkins-service.yaml --namespace jenkins

After setup Jenkins (see slides 4), let’s add Kubernetes support

• Go to Manage Jenkins, then Manage Nodes and Clouds, go to the setting of the built-in node and set the number of executors to 0.

• Go to Manage Jenkins, then Manage Plugins
  • Type Kubernetes into the search box and select the Kubernetes plugin.
  • Click Install without Restart.
  • Scroll to the bottom of the following page and check the Restart Jenkins after installing box.
  • Wait until Jenkins restart and log back in.

• Manage Jenkins, then Manage Nodes and Clouds, then Configure Cloud.
• Select Kubernetes from Add a new cloud dropbox.

7. Setup Jenkins/Kubernetes: configure Kubernetes Cloud details

• Run kubectl cluster-info to get the information about the Kubernetes control plane.

$ kubectl cluster-info

• Enter the information as shown in the figure below:
  • Kubernetes URL: use the information from Kubernetes control plane.
  • Check Direct Connection box.
  • Click Test Connection to confirm successful connection.

8. Setup Jenkins/Kubernetes: configure Pod Templates

• Click Pod Templates.
  • Click Add Pod Template.
  • Click Add Container.
• Fill in information about the template for Pod/Container as shown below

• Click Save.

9. Launch a new pipeline

• Create a branch from your hello repository and named it hello_kube. Make sure that this hello_kube branch is copied from the instructor’s hello repo’s hello_kube branch

• In Jenkins, create a New Item of type Pipeline and name it hello_kube.
• Under Build Triggers and check GitHub hook trigger for GITScm polling.
• Under Pipeline select Pipeline script from SCM.
• Once SCM appears, select Git and provide the Repository URL for your hello repo.
• Under Branch to build, change */master to */hello_kube.
• Make sure that Script Path, enter Jenkinsfile.
  • This is the Jenkinsfile in the hello_kube branch.
  • Click Apply.

• Click Save.

10. Where the wild things are

Key Points