In this blog post we are going to detail the process of setting up a continuous delivery environment with Jenkins starting from a basic CentOS install. We are going to illustrate a step by step process, explain it, and present some solutions to issues which might arise.
Briefly our journey will take you through these steps:
1. installing a VNC server
2. adding Jenkins
3. adding maven to the system
4. creating a Jenkins job
Why did we setup a continuous build environment?
It basically boils down to these two facts; A) that we needed to have stable tests (no false positives/negatives) generated by automation and B) a way to test quick (late modifications before sending out the kit or making a demo).
What we have is a project with Maven profiles for building and running our tests (Selenium based). In case you’re wondering how to do such a thing, please run a google search on “How to Setup a CI using Eclipse, Selenium Webdriver, Maven, and Hudson”.
We started with a CentOS Linux server installed and this is briefly what we did:
1. Install VNC Server to get GUI access to the machine (as it did not have a monitory + keyboard)
yum install vnc-server edit /etc/sysconfig/vncservers to a config VNCSERVERS="1:cmsivnc" VNCSERVERARGS="-geometry 1024x768"
Check your server which will start at the next boot: /sbin/chkconfig vncserver on
Start it manually now: /sbin/service vncserver start
Connect with your favorite VNC Client to test it works to: <your_ip>:1
If you are able to connect, congratulations! If not, then you can check your firewall to see if the port (5901) is open.
add the line:
-A INPUT -p tcp -m state --state NEW -m tcp -m multiport 5901:5999 -j ACCEPT to /etc/sysconfig/iptables and restart iptables ( service iptables restart )
So you’ll have VNC access to 99 VNCscreens.
2. Install Jenkins
First check JAVA Development Kit is installed, if not do run the following command:
yum install jdk-7u51-linux-x64.rpm
get Jenkins, install, start
wget http://pkg.jenkins-ci.org/redhat/jenkins-1.555-1.1.noarch.rpm yum install jenkins-1.555-1.1.noarch.rpm service jenkins start
check the server is running:
[root@server~]# ps -ef | grep jenkins
should have a line as:
jenkins 28520 1 0 Apr15 ? 00:19:24 /etc/alternatives/java -Dcom.sun.akuma.Daemon=daemonized -Djava.awt.headless=true -DJENKINS_HOME=/var/lib/jenkins -jar /usr/lib/jenkins/jenkins.war --logfile=/var/log/jenkins/jenkins.log --webroot=/var/cache/jenkins/war --daemon --httpPort=8080 --ajp13Port=-1 --debug=5 --handlerCountMax=100 --handlerCountMaxIdle=20
and check the log file
if you have something like:
WARNING: FAILED SelectChannelConnector@0.0.0.0:8080: java.net.BindException: Address already in use java.net.BindException: Address already in use at sun.nio.ch.Net.bind0(Native Method)
The port 8080 is already taken so chose another (8081) by editing /var/lib/jenkins/jenkins.model.JenkinsLocationConfiguration.xml and changing the line to use the new port <jenkinsUrl>servername:8081/</jenkinsUrl>
service jenkins restart
and add the new port in iptables as done above
-A INPUT -p tcp -m state --state NEW -m tcp -m multiport 5901:5999,8081 -j ACCEPT
Now we have a running Jenkins. Just check the IP of the server:8081 in your favorite browser.
3. Adding Maven to the system
As currently we have Jenkins running we should define some jobs for it as well, this depends on your project, but first we should add a project management and comprehension tool.
In our case we use Maven for the builds so we installed that and configured it in Jenkins.
extract it in /usr/local and link to /usr/local/maven
We thought of doing a bit of configuration on default Jenkins (from Manage Jenkins link Configure Jenkins) such as the number of executors (Manage Jenkins -> configure -> # of executors) but ran into jobs running in parallel which were using the same port so better keep it to 1 if you can’t control the types of jobs running in parallel
4. Creating a Jenkins job
Next step is to actually create a job (New Item) based on your particular project
We have a step which builds the system, one which deploys an Apache/tomcat and our app inside and then a less gracious shell to execute mave profile with tests:
mvn -pl selenium-tests verify -P seleniumTest
Then we ran into some errors (from in the console of the job)
Taking aside the trivial such as:
FATAL: command execution failed java.io.IOException: Cannot run program "mvn" (in directory "/var/lib/jenkins/jobs/test/workspace"): error=2, No such file or directory
where your jenkins user does not know or have enough rights to run maven.
We had some of case where DISPLAY variable was not set so the fix was to add
1.0 should be replaced by the value available in your environment (to find out add an env to a Jenkins job shell script and see what value the DISPLAY gets)
and that Webdriver could not start with a message in jenkinse console output (Error: no display specified). That was fixed by using the command:
Of course this will not last through a system restart and a quick fix is to create an executable file:
touch /etc/X11/xinit/xinitrc.d/jenkinsuser.sh chmod 755 /etc/X11/xinit/xinitrc.d/jenkinsuser.sh
with content as:
#!/bin/sh [ -x /usr/bin/xhost ] && [ -x /usr/bin/id ] && xhost +si:localuser:jenkins >& /dev/null
With these steps you can have the build and test running and actually see them in a GUI by connecting to your VNC server to the same DISPLAY and enjoying the show. Once tests are done, successfully, you can deliver.
Setting up the specifics to run Selenium can be made simpler by using Jenkins plugins. For a server with GUI use Xvnc plugin (install from Manage Jenkins link Plugin Manager on the Available tab) and configure to your system specifics (in Manage Jenkins link Configure Jenkins). In case the server you’re running on does not have a GUI installed use the Xvfb plugin. Same places you can configure as Xvnc plugin. The only down-side is that you cannot see the tests running. The closest thing I found is the handy xwud command which lets you examine the content of the frame buffer file Xvfb uses.
In the conclusion I would like to draw your attention to some benefits we observed:
The purpose of this post is to help others save time in setting up a similar setup. Hope it helps and if you have questions drop me a word using the comment box below.