Add a new Ruby version

Infrastructure

Last updated: 3 Aug 2020

The Ruby language is a core part of GOV.UK - most of our applications are written in it.

Managing different versions of Ruby

Each app can use whatever version of Ruby it wants. We manage this with rbenv.

Setting up rbenv

We set up rbenv differently depending on what's going on:

Interactive login shells: /etc/profile.d/rbenv.sh sets up rbenv
Applications: govuk_setenv and a .ruby-version in the app directory set up rbenv
Deployment: Capistrano uses a non -login shell so we set default_environment (commit)
Testing: Jenkins uses a non-login shell so we add /usr/lib/rbenv/shims to the PATH
Cronjobs: some cronjobs start with /bin/bash -l -c which runs a login shell

Add a new Ruby version in puppet

You will need to build a new fpm package with the new Ruby version. This package can then be copied to Aptly machine, and the new version added to puppet.

Building the fpm package.

Add a new recipe for the ruby version in Packager. The folder name will be the Ruby version, and contain a recipe.rb file. See previous entries for examples. The recipe will require the SHA256 of the version's tar.gz, available at Ruby cache.
Once the Packager change is merged, build the package.

Use the VM to test the recipe

To make sure it has been successful:

rbenv versions to make sure your version is available
rbenv local X.X.X to use your new version
ruby -v to make sure your version is in use

Copying to Aptly

See Uploading a new package

Add to Puppet

Once it's available as a package in Aptly you can install it everywhere using Puppet. Machines only run apt-get update periodically so it might take a little time for the package to become available.

Testing whether a version of Ruby is in use

You can use the Fabric task rbenv.version_in_use to find out which applications are using a specific version of Ruby on GOV.UK. For example:

fab production puppet_class:govuk_rbenv::all rbenv.version_in_use:2.3.1