Saturday, August 29, 2015

Configure Jenkins on Tomcat


I installed Jenkins under Tomcat 7. Initially, it appears so easy. After I copied war file under webapps directory, I can access Jenkins from the browser right away. However, that's only the beginning. It has been a couple of days, I'm still fighting with endless problems.

1.Where is the configure file for Jenkins.

I got my clue from this post http://stackoverflow.com/questions/9640030/where-does-jenkins-store-job-and-node-configuration

The installer username for Jenkins is "tomcat", but "tomcat" home directory is not in the standard place like my normal login user.

run this:

$ grep tomcat /etc/passwd
tomcat:x:496:10002::/opt/apache-tomcat-7.0.63:/bin/bash

that tells me "tomcat" home directory is actually /opt/apache-tomcat-7.0.63.

Do a "ls -a" in the directory reveals Jenkins configuration is stored under ".jenkins". That solved my puzzle since a week ago.

It would be too easy if that's the end of the story. So the question is:

2. Who is running Jenkins' processes?

Since Jenkins is installed as an web app, when Jenkins executes various processes, which user name is it using? It turned out, it has huge significance as I start to configure build jobs.

I finally realized that the user who starts "tomcat" will be the user who owns all Jenkins processes. I wasn't paying close attention to this before. I was using either "root' or "tomcat" to run "startup.sh" for tomcat. Imagine, when you run "startup.sh" as "root", then Jenkins configure directory will end up  under "/root/.jenkins", that can create so many unintended consequences!
1). First, it switches ".jenkins" directory. Whatever, you have configured under "tomcat" suddenly disappear from you. 2). Then there is the user permission issue, A command runs fine with "root" user may not run under "tomcat, such as "ssh-keygen" command. 3). finally there is a "credential" or identity problem. It took me forever to figure out I am fighting with two SSH keys (one is for "root" and one is for "tomcat", when I was configuring "git" integration. That alone deserves another blog that I'll post after this one.

3. Environment variables: I created a .bash_profile for "tomcat":

JAVA_HOME=/opt/jdk1.8.0_45 export JAVA_HOME M2_HOME=/opt/apache-maven-3.3.3 export M2_HOME M2=$M2_HOME/bin export M2 PATH=$PATH:$JAVA_HOME/bin PATH=$PATH:$M2 export PATH

otherwise, "mvn", java may not be available inside Jenkins.
I think I may need to set JENKINS_HOME later as well, I'm worried I may encounter other issues without proper jenkins home env.

Just too many things to worry about...

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