What is Jenkins

Jenkins (http://jenkins-ci.org) is almost the standard for CI (continuous integration) now. It has a big community with lots of plugins for nice features, in order to learn those things, it will be good to practice it by setting the environment.

Also if you want to introduce new features of jenkins to others, you want to have a demo environment for them quickly.

How this can be done easily? Docker is my favorite to achieve this.

In this blog series, I use some examples to describe how to achieve this step by step.

Demo jenkins small feature – AnsiColor plugin

Jenkins AnsiColor plugin is one of my favorite small plugin, it can turn console log looks better.

So I want to setup a demo environment for everyone can try it locally without installation, since mostly we want to try before deployment.

Result

Let’s see result first since you may just interesting this feature

docker run –p 8080:8080 –t larrycai/jenkins-demo1

The jenkins is started in console, then open the browser to access 8080 port.

Looks great, one craft sample job is there and Jenkins is latest LTS version 1.580.1

Click Craft job and run it, then check the console, great, it shows the color in console

Then back to see how it is configured

Now the demo is completed

How it works

Here is the Dockerfile, see source

FROM ubuntu:trusty

MAINTAINER Larry Cai <larry.caiyu@gmail.com>

ENV REFRESHED_AT 2014-11-03

RUN apt-get update  && apt-get install -qqy curl openjdk-6-jdk

ENV JENKINS_HOME /opt/jenkins/data
ENV JENKINS_MIRROR http://mirrors.jenkins-ci.org

# install jenkins.war and plugins

RUN mkdir -p $JENKINS_HOME/plugins $JENKINS_HOME/jobs/craft
RUN curl -sf -o /opt/jenkins/jenkins.war -L $JENKINS_MIRROR/war-stable/latest/jenkins.war

RUN for plugin in chucknorris greenballs scm-api git-client ansicolor description-setter \
    envinject job-exporter git ws-cleanup ;\
    do curl -sf -o $JENKINS_HOME/plugins/${plugin}.hpi \
       -L $JENKINS_MIRROR/plugins/${plugin}/latest/${plugin}.hpi ; done

# ADD sample job craft

ADD craft-config.xml $JENKINS_HOME/jobs/craft/config.xml

# start script

ADD ./start.sh /usr/local/bin/start.sh
RUN chmod +x /usr/local/bin/start.sh

EXPOSE 8080

CMD [ "/usr/local/bin/start.sh" ]

Started with installing openjdk/curl package and setting related environment which is needed when jenkins starts.

Jenkins app (.war) can be found in http://jenkins-ci.org/, you can choose latest version or LTS (Long Term Support) stable version, here I choose LTS version http://mirrors.jenkins-ci.org/war-stable/latest/jenkins.war

All the plugins can be found in mirror sites: http://mirrors.jenkins-ci.org/, you need to find the Plugin Id for your plugin like ansicolor, which can be mapped to http://mirrors.jenkins-ci.org/plugins/ansicolor/latest/ansicolor.hpi

In jenkins, job’s configuration is saved as config.xml, you can prepare in advance and put it under $JENKINS_HOME/jobs/craft in docker image.

<?xml version='1.0' encoding='UTF-8'?>
<project>
  <actions/>
  <description></description>
  <keepDependencies>false</keepDependencies>
  <properties/>
  <scm class="hudson.scm.NullSCM"/>
  <canRoam>true</canRoam>
  <disabled>false</disabled>
  <blockBuildWhenDownstreamBuilding>false</blockBuildWhenDownstreamBuilding>
  <blockBuildWhenUpstreamBuilding>false</blockBuildWhenUpstreamBuilding>
  <triggers/>
  <concurrentBuild>false</concurrentBuild>
  <builders>
    <hudson.tasks.Shell>
      <command>#!/bin/bash
env
echo -e "\e[1;31;42m Using docker to demo is awful, v5 \e[0m"
echo see more in http://misc.flogisoft.com/bash/tip_colors_and_formatting
</command>
    </hudson.tasks.Shell>
  </builders>
  <publishers/>
  <buildWrappers>
    <hudson.plugins.ansicolor.AnsiColorBuildWrapper plugin="ansicolor@0.4.0">
       <colorMapName>xterm</colorMapName>
    </hudson.plugins.ansicolor.AnsiColorBuildWrapper>
  </buildWrappers>
</project>

The most easy way is to get the file from running jenkins directly (append config.xml in your job URL)

And in the end, add small start.sh which will start your jenkins during startup.

exec java -jar /opt/jenkins/jenkins.war

Then you can build your docker image

docker build –t larrycai/jenkins-demo1 .

How to share it public

You can put your project into github or bitbucket and run your build in http://hub.docker.com , then others can simple run docker command to run it (you can search for guideline)

Summary

In this blog, we demoed how to dockerize your jenkins application with sample job, which is well prepared for the configuration. It will be easily for your audience to know your demo feature.

Now you can pack your nice jenkins feature into the docker.

In next blog, I will show how to organize the JENKINS home better

Docker can help us a lot.