Frozen gems in Merb == gems installed inside the application.

That's clever because now you can use the standard tools for installing and managing the installed gems. For example, you get dependency checking and so on for free. Add -i gems to the command line options to specify the install location.

gem install merb-core -i gems

That's the simplest case (run it from the root of you merb app). It fetches the merb-core gem from the gem servers and installs it inside a gems directory.

However, in many cases that's not what you want. Really you want to freeze the version you're currently developing on. Maybe one you've installed from the merb-core git repository. That's really easy because you have the gem package files on your system already. For me they're in /Library/Ruby/Gems/1.8/cache. Get your location by running gem environment gemdir and look for a cache folder. Install the package with

gem install /Library/Ruby/Gems/1.8/cache/merb-core-0.9.1.gem -i gems

You should add /gems/doc to your .gitignore since you definitely don't want ri and rdoc files in your repository. Alternatively add --no-ri --no-rdoc to the gem install command.

The final challenge is actually getting merb started. Right now I'm relying on a pastie that google found for me (I'm sorry I have no idea who the author is). Make that executable and use it to run merb with the usual merb command line options. That's surely a bit of a hack though and I'm hoping that someone will point out a better way :) Update: Thanks Steve - I hadn't spotted the generator. Run merb-gen freezer frozen-merb and then run Merb with ./script/frozen-merb passing the usual merb command line options.