Jenkins on Raspberry Pi 2

I had an old Raspberry Pi which was fun to play with but really too underpowered to do much with. However, I recently took part in the BCS Womens App-athon World Record attempt where I had a chat with a guy about Pis and running Minecraft and he pointed out the newer Pi2 was quite capable of running MCServer (a C++ implementation of a Minecraft Server).

But I wanted a Pi2 for something more serious - something running Jenkins to manage the various bits of codes I knock up. I'd tried this on the original Pi but it was unusable...

Install from instructions Random Code Solutions were ok but the version installed via apt-get was old and slow and couldn't easily be updated (managed package). I removed this and installed Tomcat 7 but this bizarrely used Java 1.6 and similarly wasn't easily changed...

Managed packages, they make life easy but you're dependent on them keeping things up to date.

So the process I finally used was:

1. Install Java 8, the Oracle version. This was already there on the version of Raspbian I was using.

2. Ensure this JVM is set as the default:
update-alternatives --config java

Should give you something like image below. Select the version corresponding to java 8...

update-alternatives --config java

3. Download Tomcat. Version 7.0.62 was the one I used.
cd /usr/local/bin
wget http://www.mirrorservice.org/sites/ftp.apache.org/tomcat/tomcat-7/v7.0.62/bin/apache-tomcat-7.0.62.tar.gz
tar -zxf apache-tomcat-7.0.62.tar.gz

4. Jenkins will complain about URI charset on startup so before installing change the URIEncoding parameter for Tomcat i18n in apache-tomcat-7.0.62/conf/server.xml to set the URIEncoding as UTF-8:
<Connector port="8080" URIEncoding="UTF-8"/>

5. Startup Tomcat

Check this is running by hitting the server: http://{server}:8080/ and you should see something like below:

Tomcat Successful Install

6. Download Jenkins (just grab the jenkins latest release though at time of writing the version I have is 1.617) and put this into the webapps folder under Tomcat. Or...
wget http://mirrors.jenkins-ci.org/war/latest/jenkins.war -O /usr/local/bin/apache-tomcat-7.0.62/webapps/jenkins.war

7. Tomcat will now deploy the WAR. This can take a little time and the easiest way to see it running is to run "top" and you should see Java consuming 100% CPU. When this drops to 0% it'll be done.

8. You should now be able to see Jenkins running on http://{server}:8080/jenkins/ (on my network it's called raspberrypi2  - genius huh!).

All done! Kind of, it's best to update all plugins and restart, configure security, set access control and configure an email server for alerting.

A simple task runs ok and Jenkins is quite responsive when nothing else is running on the server...

I can run MCServer ok at the same time but Jenkins gets slow when the world is in use. Otherwise no issues yet though I suspect as I add more jobs it'll probably run out of RAM. We shall see. Perhaps I'll be buying another one of these Pi2's; wife will be pleased.. ;)

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