Installing Jenkins OS X Homebrew

Homebrew is the easiest way to install and manage applications on OS X. Let's go through how we
install and configure Jenkins.

Installation

Follow the instructions at http://brew.sh/ if you have not had Homebrew installed. Then, let's proceed to install Jenkins

$ brew update && brew install jenkins

Jenkins is a Java web application. Download and install the latest Java Runtime Environment manually, or use Homebrew Cask to install it

$ brew cask install java

Starting Jenkins

After Jenkins is installed successfully, follow the instructions to start Jenkins on login

$ ln -sfv /usr/local/opt/jenkins/*.plist ~/Library/LaunchAgents

If you want to configure Jenkins to launch on system startup, for all users on OS X, then copy the plist file to the system Launchd location instead

$ sudo cp -fv /usr/local/opt/jenkins/*.plist /Library/LaunchDaemons
$ sudo chown `whoami` /Library/LaunchDaemons/homebrew.mxcl.jenkins.plist

You can always start Jenkins manually with

$ /usr/local/bin/jenkins

or if you have set up your PATH correctly when installing Homebrew, simply

$ jenkins

Restarting Jenkins

If you have an older version of Jenkins and you are upgrading it, then you can restart it this way:

$ launchctl unload ~/Library/LaunchAgents/homebrew.mxcl.jenkins.plist
$ launchctl load ~/Library/LaunchAgents/homebrew.mxcl.jenkins.plist

Jenkins Options

The default Jenkins startup command in ~/Library/LaunchAgents/homebrew.mxcl.jenkins.plist is very simple.

      <string>/usr/bin/java</string>
      <string>-Dmail.smtp.starttls.enable=true</string>
      <string>-jar</string>
      <string>/usr/local/opt/jenkins/libexec/jenkins.war</string>
      <string>--httpListenAddress=127.0.0.1</string>
      <string>--httpPort=8080</string>

Launchd starts a java command, listening on only the loopback network interface and using the port 8080 and listen to SMTP connection over TLS. 

Network Port

8080 is a common network port for web development. Tomcat defaults to 8080. On my machine, I run Gitbucket on 8080. Let's change it to "8181"

<string>--httpPort=8080</string>

Java Options

If you have any additional Java runtime options, add them to the configuration file. For example, we want to set:

• Initial and maximum VM size to 1G
• Use CMS garbage collector for more responsive system
• Garbage collect PermGen classes - more details here
• Limit PermGen size

    <string>-Xms1G</string>
    <string>-Xmx1G</string>

    <string>-XX:+UseConcMarkSweepGC</string>
    <string>-XX:+CMSClassUnloadingEnabled</string>
    <string>-XX:MaxPermSize=256m</string>

More information for Hotspot Java VM options.

 Jenkins Plugins

A fresh Jenkins installation is ready to be used, especially if you only need to manage Java projects. There are many Jenkins plugins that can make Jenkins much more powerful. To access Plugin Manager, go to Jenkins ⇒ Dashboard ⇒ Plugin Manager or the url http://jenkins:8181/pluginManager/available.

The easiest way to install a plugin is to view the list of all published plugins in the Plugin Manager, click and Install and restart Jenkins. To install a plugin manually, copy the plugin-name.hpi file to Jenkin's directory. In the Homebrew installation, that will be $HOME/.jenkins/plugins. Restart Jenkins and the plugin will be installed.

These are the plugins I have installed:

• Git
• Gitbucket

Jenkins configuration

Besides the launchd configuration file explained above, all other Jenkins configuration is stored in $HOME/.jenkins. The main configuration file is config.xml. You really should not edit the configuration files by hand. Use the Jenkins web interface to make changes http://jenkins:8181/manage

Upgrading Jenkins

As a continuous integration server, Jenkins itself is frequently updated. You can check if a new version of Jenkins is available

$ brew update && brew outdated jenkins

Upgrading jenkins is as easy as

$ brew upgrade jenkins

Homebrew's default behaviour is to keep older versions. If you don't need the older versions of Jenkins anymore, you can remove them

$ brew cleanup jenkins

Preserve Configuration And Plugins

You don't want to set up Jenkins all over again on every upgrade. The good news is, Jenkins server files and your configuration are in separate locations. Your new Jenkins installation will automatically pick up your existing configurations and plugins at "$HOME/.jenkins"

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