Setup Ubuntu Jenkins Master

By Kristina Bankova | March 18, 2018 | Comments 0 Comment

This article is a guide for a setup of a new Ubuntu Jenkins master. The setup is made entirely via the terminal, without any GUI client. The migration of the data is done through Windows machine. Ubuntu is selected as OS for Jenkins master because it is very light and with good performance. After the setup the occupied hard disk space was 4GB.

If you do not feel quite comfortable with terminal commands, see this article.

After you log in on your Ubuntu machine, it is time to install some packages:

1. Add repository key to the machine. The system will return OK when ready.

wget -q -O - https://pkg.jenkins.io/debian/jenkins-ci.org.key | sudo apt-key add -

2. Add the Debian package repository address to the server’s sources.list:

echo deb https://pkg.jenkins.io/debian-stable binary/ | sudo tee /etc/apt/sources.list.d/jenkins.list

3. Update packages:

sudo apt-get update

4. Install Jenkins:

sudo apt-get install jenkins

If you need specific Jenkins version use:

sudo apt-get install jenkins=2.89.3 Just put your preferred version in the place of 2.89.3.

5. Install git:

sudo apt-get install git

6. Install Node.js:

sudo apt-get install nodejs

7. Install tools for mounting Windows folders. This is needed if you will transfer files to/from a Windows machine.

sudo apt-get install cifs-utils

8. Install the WinDirStat GUI-less equivalent in Ubuntu. It is extremely useful when you run out of hard disk space and you need to know what is the cause for that.

sudo apt-get install ncdu
There is a nice NCDU guide if you want to learn more.

9. Make directory on the Ubuntu machine that will contain the mounted Windows share.

mkdir ~/windows-share-migration

The tilde (~) symbol is substitute for /home/yourusername.

10. Mount Windows folder that contains your Jenkins backups or configurations files. Use IP instead of machine name. Jenkins user is with uid 112 in the example below. The uid is needed if you want the Jenkins process to have write permissions in the mounted folder.

sudo mount.cifs //myIP/myWindowsSharedFolder/ ~/windows-share-migration -o user=myusername,domain=mydomain,vers=3.0,uid=112,gid=1000
Unmount share:

sudo umount ~/windows-share-migration

See all mounted:

mount

11. Get admin password so that you can login in the newly created Jenkins server web interface:

sudo cat /var/lib/jenkins/secrets/initialAdminPassword

12. Login with admin password on http://YourJenkinsUbuntuMachineIP:8080 on your Windows PC.

13. Install ThinBackup plugin if you plan to restore settings from other Jenkins server with it. I have some mixed feeling for this plugin. From one side, it does a good job in filtering your most important configuration and backing them up. From other side you should be aware that the archive can be corrupted if you select improper setting. So to be on the safe side, do a test migration with it before the real one.

14. Restore the ThinBackup archive or copy files from your old Jenkins server to the new Ubuntu server. Do not forger secrets and email-templates folders.

sudo cp -a ~/windows-share-migration/secrets/. /var/lib/jenkins/secrets/

15. If you have copied files with root, change their owner back to jenkins process, R option will do it recursively:

sudo chown -R jenkins:jenkins /var/lib/jenkins

16. Change Java heap size:

In Windows this is done in jenkins.xml file.
In Ubuntu you should change the `JAVA_ARGS=”-Xmx2048m”` in the /etc/default folder, jenkins file.
Check out this article for more details.

17. Add your SSL certificates to cacerts java security folder if you use any (/usr/lib/jvm/java-8-openjdk-amd64/jre/lib/security/cacerts). This step could be also needed if a build is failing because of this error:

Caused by: javax.net.ssl.SSLHandshakeException: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target

If you upgrade the Java version you could follow one of the options below. Option 2 is the recommended one.

Copy the old version cacerts file into the new Java home /jre/security folder so that it overwrites the new version of cacerts.
Import the certificates into the new java version cacerts file.
Make a copy of the file just in case the import breaks the file.

sudo cp -a /usr/lib/jvm/java-8-openjdk-amd64/jre/lib/security/cacerts ~/windows-share-migration/

Export the certificate from the Chrome Browser. Place the certificate in the same folder as the cacerts file. Import it in the current Java certificates store.

sudo keytool -import -alias yourcertificate201901 -keystore cacerts -file yourcertificate201901.cer

Configuration Files

You can check the folders used by Jenkins in the system info. (http://YourJenkinsUbuntuMachineIP:8080/systemInfo)
If you followed the steps above your Jenkins home will be /var/lib/jenkins.
Several other folders that contain Jenkins configurations (jenkins.xml does nothing in Ubuntu system):
War file is in /usr/share/jenkins/jenkins.war.
Logs are in /var/log/jenkins. If you have suddenly run out of disk space, graphs for the test builds are missing or you see that the log files are big, check out this article.
Java certificate store is in /usr/lib/jvm/java-8-openjdk-amd64/jre/lib/security.
Jenkins defaults are in the folder /etc/default/.
Logrotate config is in /etc/logrotate.d/. The file is named jenkins. For logrotate configuration check out this article. If you need a beginner guide on logrotate, check out this article.

Additional Resources

Install Jenkins on Ubuntu 16.04 Guide
Setup firewall
SSL setup

Summary

My opinion is that Jenkins server is much more stable on Ubuntu than it is on Windows. This is why I wrote this article on you how to setup Jenkins server on Ubuntu machine. The article consists of easy to follow steps to install new Jenkins server, configure it and migrate data from a shared Windows folder.