Run Docker commands inside Jenkins Docker container

#docker #jenkins #devops

Introduction

If you want to initiate docker containers from within your jenkin containers,this is what you have to do:

In the Jenkins Dockerfile, add commands to get docker, docker-compose installed.
bind mount the docker socket.

And thats it! This is how the Dockerfile looks like:

Jenkins Dockerfile

FROM jenkins/jenkins

# Docker install
USER root
RUN apt-get update && apt-get install -y \
       apt-transport-https \
       ca-certificates \
       curl \
       gnupg2 \
       software-properties-common \


RUN curl -fsSL https://download.docker.com/linux/debian/gpg | apt-key add -
RUN apt-key fingerprint 0EBFCD88
RUN add-apt-repository \
       "deb [arch=amd64] https://download.docker.com/linux/debian \
       $(lsb_release -cs) \
       stable"

RUN curl -L https://github.com/docker/compose/releases/download/1.27.4/docker-compose-`uname -s`-`uname -m` -o /usr/local/bin/docker-compose \
&& chmod +x /usr/local/bin/docker-compose

RUN apt-get update && apt-get install -y docker-ce-cli

USER jenkins

Now to build the image:

docker build -t jenkins-docker .

To run the docker-image, including the volume mounts:

 docker run -d --group-add $(stat -c '%g' /var/run/docker.sock) \
-v /var/run/docker.sock:/var/run/docker.sock -p 8080:8080 -p 50000:50000 \
-v `pwd`/jenkins:/var/jenkins_home --log-opt max-size=50k   --log-opt max-file=5   --name jenkins -P jenkins-docker

Here you can see docker.sock file has been mounted.Also, jenkins_home folder has been mounted so that you can persist the information regarding your pipeline/configuration/users etc.
Dont forget to take backup of jenkins_home directory!

I have uploaded a makefile and a similar Dockerfile on github.

And thats it!