Jenkins (CI) Pipeline Setup

Speed ​​and reliability are critical in modern software development.
In this guide, you will integrate Jenkins running on your Ubuntu 20.04 server with GitHub and set up a CI pipeline that runs automatic tests with every code submission.

Thanks to Docker containers, tests run in isolation and environment differences are eliminated.

What Will You Learn in This Guide?

• Giving Docker permission to Jenkins server
• Set up Token and Webhook between GitHub and Jenkins
• Defining the CI process as code with Jenkinsfile
• Triggering automatic tests with GitHub push actions

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Prerequisites

Before you start, you should have the following ready:

• Server: Ubuntu 20.04, at least 1 GB RAM (ex: GenixNode VDS)
• Software: Jenkins (SSL configured), Nginx and Docker
• Account: GitHub account

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1. Granting Docker Privilege to Jenkins User

We must authorize Jenkins to run Docker containers.

sudo usermod -aG docker jenkins

• This command adds the Jenkins user to the Docker group.

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Verify authorization:

grep docker /etc/group

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• Restart Jenkins for the changes to take effect:

sudo systemctl restart jenkins

Note: From the Jenkins panel, in the Manage Jenkins → Manage Plugins section

• Make sure Docker and Docker Pipeline plugins are installed.

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2. Creating a GitHub Personal Access Token (PAT)

An access key is required for Jenkins to monitor your GitHub repository.

• Follow this path on GitHub:

1. Settings → Developer settings → Personal access tokens

2. When creating a token, grant these permissions:

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3. repo:status

4. repo:public_repo

5. admin:org_hook

6. Copy the token as soon as you create it. It cannot be viewed later.

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3. Defining GitHub Token to Jenkins

• Follow this path in the Jenkins panel:

1. Manage Jenkins → Manage Credentials → (global) → Add Credentials

Fill in the fields as follows:

1. Kind: Secret text

2. Secret: GitHub token

3. Description: GitHub CI Token

Save.

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Then:

1. Manage Jenkins → Configure System → GitHub

2. Add new GitHub Server

3. Select token as Credential

4. Verify with test connection

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4. Preparing the Sample Project

• We use a ready-made Node.js project to test the CI process.

• Fork the following project to your own GitHub account:

http//github.com/content-demo/hello-hapi

• This project contains a Jenkinsfile.

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5. Jenkinsfile Structure

pipeline {
    agent {
        docker {
            image 'node'
            args '-u root'
        }
    }

    stages {
        stage('Build') {
            steps {
                sh 'npm install'
            }
        }
        stage('Test') {
            steps {
                sh 'npm test'
            }
        }
    }
}

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• This structure:

1. Runs tests in Docker

2. Jenkins isolates the host server

3. Conforms to CI standards

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6. Creating a Jenkins Pipeline

1. On the Jenkins main screen:

• New Item → Pipeline

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Settings:

1. GitHub project: Repo URL

2. Build Trigger GitHub hook trigger

3. Pipeline Definition: Pipeline script from SCM

4. SCM: Go

5. Repository URL: Forked repo

6. Save.

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7. First Build and Webhook Creation

For automatic addition of the webhook, the first build is started manually.

On the Pipeline screen:

• Build Now

After the build is completed, go to GitHub → Settings → Webhooks

You will see the Jenkins webhook created.

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8. Testing Auto Trigger

• Make a small change in the GitHub repo and commit it.

• You will see a new build starting automatically in the Jenkins panel.

• Your CI line is now active

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Frequently Asked Questions (FAQ)

1. Why do we use Docker agents? It ensures that tests run in an isolated and clean environment.

2. What should I do if the webhook does not occur? You can add a manual webhook from the GitHub repo settings.

3. Is it necessary to use Jenkinsfile? No, but “Pipeline as Code” is the industry standard.

Result

You have established a modern GitHub-integrated, Docker-based Jenkins CI pipeline on Ubuntu 20.04. Now every commit is automatically tested and errors are caught early.

You can safely scale your CI/CD processes by running this structure on the GenixNode infrastructure