Jenkins Installation & Configuration CentOs

Practical guide for installing Jenkins as part of setting up Continuous Integration (CI) server.

This guide can be applied to any Linux distribution, but tested only on Centos 6.6.

Git Bare Repo

Create a new user called git that will be used to create the bare git repo. Add ssh authorized_keys file to allow ssh authentication without password. Prevent interactive ssh login to git user account by changing login shell to the special git-shell.

adduser git
su git - # Switch to git user
cd
mkdir .ssh && chmod 700 .ssh
touch .ssh/authorized_keys && chmod 600 .ssh/authorized_keys
exit # exit git shell and return to root user
cat /root/.ssh/authorized_keys >> /home/git/.ssh/authorized_keys
which git-shell >> vi /etc/shells
chsh git -s `which git-shell`

Make sure that the server has Git installed, then follow the guide to create new bare git repository.

Post Git Init Checks

After creating the new Git bare repository, remember to: * You have added all allowed users passwords in the .ssh/authorized_keys file in git home directory.

Jenkins Installation

Jenkins official documentation for installation covers the basic steps and gotchas that you might face while installing Jenkins.

Post Installation Checks

  • Make sure that Jenkins default port (8080) is open in the firewall configuration.
  • Jenkins will try to execute binaries from /tmp folder. Make sure that /tmp folder is not mounted with option noexec using mount command. Otherwise (change Jenkins temporary folder](#change-jenkins-temp-folder)

Change Jenkins Temp Folder

If you have problems starting Jenkins and the log say it can’t execute with exception like InvocationTargetException “Operation not permitted”, most probably you’ll need to change the temporary folder that Jenkins uses.

  1. Open /etc/sysconfig/jenkins.
  2. Change the Java options line
  • From: JENKINS_JAVA_OPTIONS=”-Djava.awt.headless=true”
  • To: JENKINS_JAVA_OPTIONS=”-Djava.awt.headless=true -Djava.io.tmpdir=$JENKINS_HOME/tmp”
  1. Find the JENKINS_HOME directory value from the same file (Usually: /var/lib/jenkins).
  2. Create an empty tmp folder inside the JENKINS_HOME directory.
  3. Make sure that the tmp folder is writable by the Jenkins user.
  4. Start Jenkins: service jenkins start

Jenkins Security Configuration

By default Jenkins allow anonymous users to do everything. To tighten Jenkins security we will prevent anonymous user from doing anything. Only authenticated user will be able to do everything.

For small and medium teams, we will use Jenkin’s Own User database. The official documentation explains the steps clearly.

To disallow anonymous users from accessing any information on Jenkins, we will use Matrix-based Security

  • Go to Jenkins Dashboard, usually http://server_domain:8080.
  • Select Manage Jenkins then Configure Global Security.
  • Click Enable Security.
  • Select Jenkins’ own user database.
  • In Authorization section, select Logged-in users can do anything.
  • Make sure you click Save
  • You’ll be promoted to create your first user. Remember the username and password.

Jenkins Git Configuration

By default, Jenkins doesn’t come with Git plugin. You’ll need to find and install the Git Plugin, configure Jenkins ssh authorization to access the bare Git repo.

  • Go To http://_server_:8080/pluginManager/available

  • Search for git

  • Select and Install GIT plugin

  • Restart Jenkins

  • Go to JENKINS_HOME directory (defaults to /var/lib/jenkins.

  • Change user to jenkins: su jenkins

  • Generate ssh keys: ssh-keygen

  • Make sure that the generated key is found at $JENKINS_HOME/.ssh/id_rsa

  • The .ssh folder has permission 700 and the id_rsa file has permission 600

  • Append file $JENKINS_HOME/.ssh/id_rsa.pub to git user authorized_keys file

    cat /var/lib/jenkins/.ssh/id_ras.pub >> /home/git/.ssh/authorized_keys

  • When creating a new workspace, make sure that the authorization is using jenkins private key file.

Jenkins Git Plugin and CentOS 6.6

Jenkins Git Plugin requires git of version 1.7.9 minimum, 1.8.x recommended. The default git version on CentOs 6.6 is 1.7.1.

As a workaround, you can use JGit a Java git implementation that is bundles with Git Client a Jenkins plugin dependency for Git Plugin.