Docker-based jenkins slaves

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Created: November 6, 2015 / Updated: May 16, 2018 / Status: unknown / 4 min read (~712 words)
DevOps docker jenkins

In this article, we'll go over how to setup Jenkins on an Ubuntu machine to run PHP 7.1 jobs. The steps should easily be adapted for any other OS and target environment.

  • Docker Slaves Plugin

  • In a Dockerfile

FROM ubuntu:xenial

COPY sources.list /etc/apt/sources.list
RUN useradd -m --uid=1001 jenkins
COPY known_hosts /home/jenkins/.ssh/known_hosts
RUN chown jenkins:jenkins -R /home/jenkins/.ssh

RUN apt-get update
RUN DEBIAN_FRONTEND="noninteractive" apt-get install -y git vim curl wget build-essential python-software-properties software-properties-common unzip

RUN add-apt-repository -y ppa:ondrej/php
RUN apt-get update
RUN DEBIAN_FRONTEND="noninteractive" apt-get install -y --force-yes php7.1 php7.1-xml php7.1-mbstring php7.1-zip php7.1-pdo-mysql php7.1-pdo-sqlite

RUN apt-get -y autoremove && apt-get clean && apt-get autoclean && rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/*
  • docker build -t your/image:1.0.0 -t your/image:latest .

  • your/image (will use your/image:latest)

This is particularly useful if you need to pull git repositories from a private repository.

As of December 2016, if you want to be able to use the SSH key in a docker container, you have to first start the ssh agent on the node used that will run the docker container and when you run the docker image, pass in the SSH_AUTH_SOCK as a volume so that it is shared with its host.

sshagent(['IDENTIFIER']) {
    docker.image('your/jenkins-slave-image').inside('--volume $SSH_AUTH_SOCK:$SSH_AUTH_SOCK') {
        // Here your SSH_AUTH_SOCK is shared with the host machine, which may be a jenkins slave
        // All commands that would use SSH for authentication (such as git or composer when installing from private repositories) should work

node('docker') {
    catchError {
        timestamps {
            wrap([$class: 'AnsiColorBuildWrapper']) {
                sshagent(['private-git']) {
                    docker.image('tomzx/jenkins-slave').inside('--volume $SSH_AUTH_SOCK:$SSH_AUTH_SOCK') {
                        stage 'Checkout'
                            checkout scm

                        stage 'Setup dependencies'
                            sh 'wget -nc'
                            sh 'php composer.phar install'

                        stage 'Test'
                            sh 'vendor/bin/phpunit'