Kubernetes agents in Jenkins - Mini Project: Build & Apply

Kubernetes Agents with Jenkins

📖 Scenario: You are setting up a Jenkins pipeline that runs jobs on Kubernetes agents. This allows Jenkins to create fresh, isolated environments for each job automatically.

🎯 Goal: Build a Jenkins pipeline script that defines a Kubernetes agent with a specific container image, runs a simple shell command inside the container, and prints the output.

📋 What You'll Learn

Create a Jenkins pipeline with a Kubernetes agent block

Specify the container image alpine:3.14 for the agent

Run a shell command echo Hello from Kubernetes agent inside the container

Print the command output in the Jenkins console

💡 Why This Matters

🌍 Real World

Many companies use Jenkins with Kubernetes agents to run CI/CD jobs in isolated, scalable environments.

💼 Career

Understanding Kubernetes agents in Jenkins is valuable for DevOps engineers managing cloud-native build pipelines.

1

Define a basic Jenkins pipeline

Create a Jenkins pipeline script with a pipeline block and an empty agent section.

Jenkins

pipeline {
    agent {}
    stages {
        // Your code here
    }
}

Need a hint?

Start with the pipeline block and add an empty agent block inside it.

2

Configure the Kubernetes agent with container image

Modify the agent block to use kubernetes with a containerTemplate specifying the container image alpine:3.14 and container name alpine.

Jenkins

pipeline {
    agent {
        kubernetes {
            containerTemplate {
                // Your code here
            }
        }
    }
    stages {
    }
}

Need a hint?

Use containerTemplate inside kubernetes agent to specify the container image and name.

3

Add a stage to run a shell command inside the container

Add a stage named Run Command with a steps block that uses container('alpine') to run sh 'echo Hello from Kubernetes agent'.

Jenkins

pipeline {
    agent {
        kubernetes {
            containerTemplate(name: 'alpine', image: 'alpine:3.14', ttyEnabled: true)
        }
    }
    stages {
        // Your code here
    }
}

Need a hint?

Inside stages, add a stage with steps that run the shell command inside the alpine container.

4

Print the output of the shell command

Add a script block inside container('alpine') to capture the output of sh(script: 'echo Hello from Kubernetes agent', returnStdout: true) into a variable output and then print it using echo output.

Jenkins

pipeline {
    agent {
        kubernetes {
            containerTemplate(name: 'alpine', image: 'alpine:3.14', ttyEnabled: true)
        }
    }
    stages {
        stage('Run Command') {
            steps {
                container('alpine') {
                    // Your code here
                }
            }
        }
    }
}

Need a hint?

Use sh with returnStdout: true inside a script block to capture and print the command output.