Caching Ruby Gems

Ruby Gems are installed into a single directory by default. You can get the location of this directory with gem environment gemdir. If you want to change this directory you can set the $GEM_HOME environment variable, this will be picked up by gem install and it’ll install the Gems to the location specified by $GEM_HOME.

How to reference env vars in input fields

You cannot simply add gem environment gemdir to the input of your Cache steps. You can only reference Environment Variables in the inputs directly, and $GEM_HOME is not set by default on the Bitrise.io VMs.

Open your app’s Workflow Editor.
Add a Script step to your workflow.

Set the $GEM_HOME environment variable in the Script step.

 - script:
     title: Set GEM_HOME env var
     inputs:
     - content: |-
         #!/bin/bash
         set -ev
         envman add --key GEM_HOME --value "$(gem environment gemdir)"

Insert the Cache:Pull step after the Git Clone but before the Android Build steps.

IMPORTANT: Make sure that your step is version 1.0.0 or newer.
Insert the Cache:Push step to the very end of your workflow.

And you’re done!