I use EngineYard, and I have a deployment that is failing. I am getting this message:
Some gems seem to be missing from your vendor/cache directory.
Could not find rspec-core-2.6.0.rc2 in any of the sources
How do I make sure those gems get in that directory?
Bundler ships a command which explicitly creates this cache
bundle package
After you've done this bundle install will check and keep the vendor/cache directory up to date.
If you then want to install the gems on a machine without checking on rubygems, you just run
bundle install --local
However, beware, if you are upgrading gems frequently (like I do every time a subrelease of Rails comes out), your vendor/cache can quickly grow.
My current project's git repository is 80mb, of which more than 30mb is data stored in vendor/cache.
It seemed like a good idea to speed up deploys, but overall its just made our repository much bigger.