Add a global cache for .gem files, shared by all Bundler and RubyGems installs

[indirect]

As discussed in #6102, it would save hard drive space, network bandwidth, and download time to have a single global cache of .gem files shared across all versions of Ruby, RubyGems, and Bundler.

My proposal for the default location for this cache is ~/.cache/rubygems/gems.

[simi]

My proposal for the default location for this cache is ~/.cache/rubygems/gems.

What about "#{Gem.cache_home}/gem/gems"? That's closer to other directories . Gem.cache_home respects XDG_CACHE_HOME and defaults to "#{Gem.user_home}/.cache" which is usually ~/.cache as suggested and other gem directories are using gem subdirectory in XDG dirs as a "namespace".

[indirect]

#{Gem.cache_home}/gem/gems sounds good to me 👍🏻

[deivid-rodriguez]

I think bundler already has an opt-in global cache, enabled with the global_gem_cache setting.

[indirect]

Sounds like we might be able to resolve this issue by turning on the global cache by default, then? 😅

[deivid-rodriguez]

Yes! Although it still wouldn't be shared by RubyGems.

[indirect]

Oh! Right, of course. I will keep this ticket open as a placeholder for a fully global gem cache, then, shared by both RubyGems and Bundler, and enabled by default. 👍🏻

[h3xx]

I think bundler already has an opt-in global cache, enabled with the global_gem_cache setting.

@deivid-rodriguez I was unable to find any references to the global_gem_cache setting. Can you please link me to the documentation and/or provide an example of how to set this up?

[deivid-rodriguez]

See https://bundler.io/v2.4/man/bundle-config.1.html#LIST-OF-AVAILABLE-KEYS.