Utilize Dockerfile Agent

Overview

Leveraging a Dockerfile agent in Jenkins lets you build a custom Docker image with all the CLI tools your pipeline requires. This approach ensures:

Consistent environments across builds
Isolation for each job
Flexibility to install any SDKs, CLIs, or dependencies

Prerequisites

Requirement	Purpose
Jenkins 2.10+	Pipeline support for `dockerfile` agent
Docker Daemon	Must be available on the agent node
Git Repository	Contains both `Jenkinsfile` and `Dockerfile.cowsay`

Ensure your Jenkins agent node has Docker installed and that the Jenkins user has permission to run Docker commands.

Step 1: Example with the Standard Node.js Alpine Image

Here’s a simple Jenkinsfile using the official node:18-alpine image:

pipeline {
    agent any
    stages {
        stage('S4 - Standard Node.js Image') {
            agent {
                docker {
                    image 'node:18-alpine'
                    label 'ubuntu-docker-jdk17-node20'
                }
            }
            steps {
                sh 'node -v'
                sh 'npm -v'
                sh 'cowsay -f dragon "Hello from Docker Container"'
            }
        }
    }
}

When executed, the first two commands succeed, but cowsay is missing:

/home/jenkins-agent/.../script.sh: line 1: cowsay: not found

The image shows a Jenkins dashboard displaying the activity of a pipeline named "pipeline-external-agent," with details on the status, run number, message, duration, and completion time of recent builds.

Step 2: Create a Custom Dockerfile

To include cowsay, create Dockerfile.cowsay:

FROM node:18-alpine

RUN apk update && \
    apk add --no-cache git perl && \
    git clone https://github.com/jasonm23/cowsay.git /tmp/cowsay && \
    cd /tmp/cowsay && \
    ./install.sh /usr/local && \
    rm -rf /tmp/cowsay

This Dockerfile:

Updates the Alpine package index
Installs Git and Perl
Clones and installs cowsay
Cleans up temporary files

Always remove temporary directories like /tmp/cowsay to keep your image size small.

Step 3: Switch to the `dockerfile` Agent

Update your Jenkinsfile to build the custom image on the fly:

pipeline {
    agent any
    stages {
        stage('S4 - Dockerfile Agent') {
            agent {
                dockerfile {
                    filename 'Dockerfile.cowsay'
                    label 'ubuntu-docker-jdk17-node20'
                }
            }
            steps {
                sh 'node -v'
                sh 'npm -v'
                sh 'cowsay -f dragon "This is running on Docker Container"'
            }
        }
    }
}

Behind the scenes, Jenkins will:

Read Dockerfile.cowsay from the workspace

Run:

docker build -t <generated-image-id> -f "Dockerfile.cowsay" .

Launch a container from the new image and execute your steps

Step 4: Confirm Successful Build

In the Jenkins console you’ll see:

docker build -t 0f559f3f6a2c220b616594d407b50bd36d837f4 -f "Dockerfile.cowsay" .
docker inspect -f '{{.Id}}' 0f559f3f6a2c220b616594d407b50bd36d837f4
v18.20.4
10.7.0
This is running on Docker Container

All commands now succeed, including cowsay.

Links and References

Watch Video

Utilize Docker Image Agent

Utilize newContainerPerStage

Shared Libraries in Jenkins

Agents and Nodes in Jenkins

Pipeline Enhancement and Caching

Pipeline Structure and Scripted vs Declarative

Jenkins Administration and Monitoring

Backup and Configuration Management

Introduction

Utilize Dockerfile Agent

Overview

Prerequisites

Step 1: Example with the Standard Node.js Alpine Image

Step 2: Create a Custom Dockerfile

Step 3: Switch to the `dockerfile` Agent

Step 4: Confirm Successful Build

Links and References

Watch Video

​Overview

​Prerequisites

​Step 1: Example with the Standard Node.js Alpine Image

​Step 2: Create a Custom Dockerfile

​Step 3: Switch to the dockerfile Agent

​Step 4: Confirm Successful Build

​Links and References

Watch Video

Overview

Prerequisites

Step 1: Example with the Standard Node.js Alpine Image

Step 2: Create a Custom Dockerfile

Step 3: Switch to the `dockerfile` Agent

Step 4: Confirm Successful Build

Links and References