So, what if you want to run jenkins locally on a mac? What if you want it to build from a private github repository, and you want it to use its own private key? And you’re on a mac?

Get Jenkins

First, you need to get jenkins. On my homebrew-enabled mac, I ran brew install jenkins. Without homebrew, you can just download the latest war file. (You will need java 6 to run jenkins.) Homebrew provides a plist for launching jenkins when you log in. If that’s adequate, then you can stop reading.

Create a service account

Next you need to create a user to run jenkins. This is the most challenging part of the process. (I used a script from a pastebin as reference.) Here’s what I did:

sudo mkdir /var/jenkins
sudo /usr/sbin/dseditgroup -o create -r 'Jenkins CI Group' -i 600 _jenkins
sudo dscl . -append /Groups/_jenkins passwd "*"
sudo dscl . -create /Users/_jenkins
sudo dscl . -append /Users/_jenkins RecordName jenkins
sudo dscl . -append /Users/_jenkins RealName "Jenkins CI Server"
sudo dscl . -append /Users/_jenkins uid 600
sudo dscl . -append /Users/_jenkins gid 600
sudo dscl . -append /Users/_jenkins shell /usr/bin/false
sudo dscl . -append /Users/_jenkins home /var/jenkins
sudo dscl . -append /Users/_jenkins passwd "*"
sudo dscl . -append /Groups/_jenkins GroupMembership _jenkins
sudo chown -R jenkins /var/jenkins

Before I ran through that, I did check that the ids were available. You can search for users with dscl . -search /Users uid 600 and groups with dscl . -search /Groups gid 600.

Also, I don’t think the uid and gid need to be the same, but most of the builtin service accounts (e.g. jabber) are, so I just went along with it.

Create the daemon

Mac OS uses launchd to control daemons and agents. It’s pretty easy to create a launch daemon. Create the file /Library/LaunchDaemons/org.jenkins-ci.plist with the following content, based on the plist from the homebrew jenkins formula. You may need to update the version number in the ProgramArguments.

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "">
<plist version="1.0">

I think I had to load the daemon (sudo launchctl load /Library/LaunchDaemons/org.jenkins-ci.plist). Rebooting should work, too.

Create an ssh key

Like I said, I wanted jenkins to have its own ssh identity. This is fairly easy: sudo -u jenkins ssh-keygen

The new key is in /var/jenkins/.ssh/ and can be copied to github, or wherever you have your source code.

Set up a build

Now you need to configure jenkins. Open http://localhost:8080/, click “Manage Jenkins”, “Manage Plugins”, then “Available”. I installed the git and github plugins. The git plugin gives you basic git functionality. The github plugin gives you links from the build info pages to github commit pages. After the install is complete, click the “Schedule a restart” button.

After jenkins restarts, configure git. From the “Manage Jenkins” page, “Configure System” and make sure the path for git is right. (It wasn’t for me: /usr/bin/git is the default, but homebrew put it in /usr/local/bin/git.)

Now, you can create your project. The rest of this post is a description of how I set up the build for my rails 3.0 project.

Click “New Job” in the menu on the left. Choose the “free-style” option. On the configuration page, set the github url prefix (e.g. Set the source code as git, with the repo url (e.g.; if your url starts with git:// or http://, then you probably don’t need to do the ssh key stuff earlier). I set branches to build to “master”, but leaving it blank is sometimes useful. I chose to Poll SCM, with a schedule of “* * * * *”, though I didn’t set that up until after I had the build mechanics set up right.

The only build step is to execute a shell. Here’s what I’m using. There are a few things to note here. I’m using a system-installed rvm, so all the ruby commands are run through it. Jenkins can collect JUnit test results and produce some trend graphs, so I use the ci_reporter gem’s ci:setup:testunit to format the results JUnit-style.

/usr/local/rvm/bin/rvm 1.8.7 exec bundle --path .bundle/gems

cat <config/database.yml
  adapter: sqlite3
  database: db/development.sqlite3
  adapter: sqlite3
  database: db/test.sqlite3

/usr/local/rvm/bin/rvm 1.8.7 exec bundle exec rake db:bootstrap db:migrate ci:setup:testunit test --trace