How to add custom gems to PDK in an Airgapped/Offline environment without functioning rubygems server

[Cinderhaze]

Describe the bug
It is difficult to add new gems to an airgapped machine without a functioning rubygems server.
The Omnibus/All in one package for the PDK makes it really easy to get started using the default/provided gems. Is there a good way to add additional gems when you don't have access to a working rubygems server?

I noticed that if you do a pdk bundle exec gem install ~/path/to.gem, it will install the gem into ~/.gem/ruby, but the pdk seems to expect things to be cached in ~/.pdk/cache/ruby`.

If I cp -r --no-clobber ~/.gem/ruby ~/.pdk/cache/ , I can then get pdk bundle install --local to work (after adding my gems to my Gemfile). Is there a better way to do this?

Expected behavior
I know it is more a lack of understanding bundler, and how things are configured for the PDK, but I had expected pdk bundle exec gem install foo.gem to install the gem 'locally' for the pdk session, and pdk bundle install --local to work with the above installed gem after adding it to your Gemfile.

Should we have instructions added to the documentation for pdk bundle install --local to function as expected with the right command to populate ~/.pdk/cache directory from some on-disk gems?

Additional context

• Your PDK installation method : Native Packages
• Your PDK version (pdk --version): 3.0.1
• Your operating system / platform : RHEL 8