When Bundler complains about “not being allowed to install to the system RubyGems” we have two solutions:

  1. Configure Bundler to install gems in the user directory, where we have write permissions; or

  2. Configure Bundler to install gems in the project directory, just like NPM installs modules locally.

Let’s explore solution 2 this time.

Inside a project directory, we can check if gems are being installed locally:

$ bundle config path
Settings for `path` in order of priority. The top value will be used
You have not configured a value for `path`

Here we can see that no path is configured. This means gems are installed in the default directory, according to $BUNDLE_PATH and $GEM_HOME.

Let’s configure this path then:

$ bundle config path 'vendor/bundle' --local

This creates a .bundle folder with a single file named config inside. Its contents are the following:

---
BUNDLE_PATH: "vendor/bundle"

Now, when the run:

$ bundle config path
Settings for `path` in order of priority. The top value will be used
Set for your local app (~/Projects/guilhermesimoes.github.io/.bundle/config): "vendor/bundle"

We can see that a path is configured. This makes it so that bundle install installs gems in the vendor/bundle folder.

Let’s try it:

$ bundle install
...
Fetching jekyll 3.7.0
Installing jekyll 3.7.0
...
Bundle complete! 4 Gemfile dependencies, 28 gems now installed.
Bundled gems are installed into `./vendor/bundle`

That’s it! Done!

Points worthy of note:

  • I recommend adding whatever you configure as your path (in this case vendor/bundle) to your .gitignore so that your gems are untracked by Git.

  • bundle install can also receive a path flag but this is not remembered in subsequent commands.

  • bundle install can also receive a deployment flag which does a bunch of funky things including changing where the gems are installed.