Overview

Documents things related to running Jenkins locally for testing of stuff / development.

We can run Jenkins locally to test out functionality related to Jenkins such as jobs/plugins or develop with Jenkins shared library instead of testing them on the actual deployed Jenkins.

Understanding

The run.sh script makes use of the .env file and a .tmpl file to substitute values using envsubst generating a .yaml file, the final output which is the .yaml file is then used as a value file to helm.

Prerequisites

• Configure your local development environment.

• How to setup MacBook for DevOps Role

• Assumes deploying to minikube

  • using the VirtualBox driver

• helm v3 CLI installed

• envsubst installed

• kubectl installed

• kubernetes-chart git repository cloned

Usage

1. In your terminal, change to the kubernetes-charts/charts/jenkins folder

2. Create a .env file with the following content, see table below for an explanation of the properties:

   1. Get your personal access token:https://docs.github.com/en/github/authenticating-to-github/creating-a-personal-access-token

   2. 1

GITHUB_TOKEN_JENKINS_EXCHANGE=<GITHUB PERSONAL ACCESS TOKEN>;

2. 3. 
      

   4. 2

NAMESPACE=jenkins-test;

2. 5. 
      

3. Run the run-local.sh script, run-local.sh local

   1. Make sure minikube is running with enough memory allocation.

   2. 1

   3. minikube start --memory=8g

   4. runs of run-local.sh is idempotent, it will do a refresh reinstall, by deleting the helm release, and the PVC.

      1. it also always switches your kubectl context to minikube

   5. Check the namespace you installed to for the status of Jenkins pod to be ready:

      1. kubectl get po -n jenkins-test

   6. The installation can take up to 10 mins

4. When it is ready, we can access Jenkins by port-forwarding to the minikube port:

   1. 1

export POD_NAME=$(kubectl get pods --namespace jenkins-test -l "app.kubernetes.io/component=jenkins-master" -l "app.kubernetes.io/instance=jenkins" -o jsonpath="{.items[0].metadata.name}")

4. 2. 
      

   3. 2

kubectl --namespace jenkins-test port-forward $POD_NAME 8080:8080

4. 4. 
      

5. Access http://localhost:8080 with the following credentials:

   1. Username: admin

   2. Password: admin

.env file properties:

Key

Default Value

Description

GITHUB_TOKEN_JENKINS_EXCHANGE

to be filled

This is your personal Github token, this is used to create a Jenkins credential that will be used to access Github repositories

It is important to take note that the token is not checked-into git, as such the generated local.yaml file with the token is added to .gitignore

NAMESPACE

jenkins-test

The namespace where to deploy Jenkins, the value is also used in some parts of the Jenkins configuration, and in subsequent commands.

Adding a Jenkins test job

Jenkins jobs are essentially .xml files, we can retrieve these files by doing the following:

• Going to the Jenkins home folder and copying the .xml file

• adding /config.xml at the end of a job URL, to retrieve the .xml job config

The job config.xml can then be appended to the helm value for the job to be persisted on subsequent runs. See local.tmpl master.jobs section

test job example

The following test job will perform the following:

• Pull dockerhub image alpine/git

  • test capability to pull images from the internet

• Run commands in the container

  • test capability to run commands in the correct container

  • test capability to spin up a ephermeral container agent

• Run the pipelinePrepare() function from jenkins-global-libraries and fail

  • This stage’s failure is to be expected.

  • test capability to use the global library

Create the test job through Jenkins UI New Item → Enter a job name → Pipeline → Scroll down to the Script textfield and copy paste the below:

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@Library('jenkins-global-libraries') _

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pipeline {

3

agent {

4

kubernetes {

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yaml '''

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apiVersion: v1

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kind: Pod

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spec:

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containers:

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- name: shell

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image: alpine/git:v2.26.2

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command:

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- sleep

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args:

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- infinity

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'''

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defaultContainer 'shell'

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}

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}

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stages {

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stage('Test') {

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steps {

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sh 'hostname'

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sh 'env'

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}

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}

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stage('Test global library') {

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environment {

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PROJECT_NAME = 'local'

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}

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steps {

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pipelinePrepare()

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}

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}

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}

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}

Adding a Jenkins shared library locally

Using the filescm plugin, we can load a Jenkins shared library that is mounted to minikube from our local workstation, this allows us to test our locally developed shared library instead of pushing it to a remote Git repository.

This is done from the following block:

1

persistence:

2

volumes:

3

- name: source-code

4

hostPath:

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path: /Users

6

mounts:

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- mountPath: /Users

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name: source-code

We mounted our host /Users directory to the pod, assuming our Jenkins shared library source codes are at /Users/mylib we can create a global Jenkins shared library under Manage Jenkins and use the FileSCM option to refer to /Users/mylib

Loading a image into minikube docker daemon

We can test private repositories(AWS ECR) images by downloading them into the minikube docker daemon.

1. First, we mount the minikube docker daemon

2. 1

3. eval $(minikube -p minikube docker-env)

2. Then we proceed to retrieve the required images, which will download them into the mounted minikube docker daemon:

Elastic Container Registry

3. In our Jenkins kubernetes agent, inorder to use the newly downloaded docker image , we need something like:

1

agent {

2

kubernetes {

3

defaultContainer 'diginex-cli'

4

yaml """

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apiVersion: v1

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kind: Pod

7

...

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- name: diginex-cli

9

image: 929981421241.dkr.ecr.ap-southeast-1.amazonaws.com/diginex-cli:latest

10

imagePullPolicy: Never

11

...

12

"""

13

}

Note the imagePullPolicy:Never , this is important so that kubernetes will not attempt to reach out to the internet, and will instead use what is available.

4. Finally, when we are done we can unmount to ensure we are using our own docker daemon:

1

eval $(minikube -p minikube docker-env -u)