Jenkins

Ruby, Jenkins and Mac OS


I’ve been using Jenkins as my CI server for a while and though user permissions has always been a bit of an issue (I’ll explain why in another blog post covering my Unity build process) running command line tools has never been to much of a problem once it got going.

At least not until I tried to run Ruby 1.9.3 via RVM on our Mac Jenkins server.

I’d developed the Ruby scripts outside Jenkins so I knew they worked, but when I came to run them through Jenkins (using nothing more than the ‘Execute Shell’ build step) it started behaving strangely. Running the script caused the step to fail instantly claiming it couldn’t find any of my installed Gems.

A quick ‘gem query –local’ on the command line listed all the gems I needed were there.

As an experiment I added a build step that installed the Trollop gem (a fantastic gem, you should check it out!) to see if that made any difference, in effect forcing the install in the service that would run the Ruby script. I was surprised when the install worked, but it installed it for Ruby 1.8 rather than Ruby 1.9.

Adding ‘ruby –version’ as a build step showed that for some reason the Jenkins server was using Ruby 1.8.7 rather than 1.9.3.

It turns out that RVM is not available when run through a non-interactive shell script, which is a bit inconvenient when you need it run as part of an automated process.

Searching around I came across this Stack Overflow answer suggesting I make changes to my .bash_profile but those changes were already present meaning I had little luck in finding a solution.

Other suggestions involved rather convoluted steps to just get the thing working, something I neither had the time for nor thought should be required.

Luckily Jenkins provides a RVM Plugin which allows the build step to run inside an RVM managed environment meaning it will respect the RVM settings I’ve set outside of Jenkins…

Now when running ‘rvm list’ via a build script shows that we have multiple versions of Ruby available with 1.9.3 set as the default.

And all of a sudden my Ruby scripts work like a charm!