What does Bundler offer over RVM?

Question

I am not sure what the differences are between these two tools. There seems to be a big overlap, but I have been using RVM and facing some miss-compatibility issues.

What does Bundler do that RVM does not?

Answer 1

They serve different purposes. RVM creates a sandbox to manage your Ruby installations. As a part of that, it also lets you define gemsets.

Bundler doesn't manage your Rubies, it works with the currently selected Ruby.

So, I think you should consider RVM as the configuration manager for your development environment, and Bundler the gem manager for an application.

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EDIT: Additional thoughts -

Whether we use RVM or not, typically we'd have to load all the gems we're going to use for an app by hand, using gem install blah, for every gem we want to use.

I end up managing my gems across multiple Rubies by hand. Once they're installed I can create gemsets using RVM, but RVM won't automatically retrieve a particular version of a gem if it's not installed, or go get it again if it was removed. Because RVM is more concerned with your Ruby environment, it mostly leaves the versioning of gems to gem and to us.

Bundler, on the other hand, does care about those missing parts in RVM. When you create the Gemfile for bundler, it will retrieve the necessary gems and specific versions if specified. So, the task of installing a Ruby app on a different machine becomes much simpler. Push the files to the other machine, then run bundle install and it'll do the rest.

It works nicely with Rails and is a sensible solution for my production files. It will be much simpler than how I have to handle Perl distributions in order to run Perl apps on the same hosts.

Answer 2

To directly answer your question...

What does Bundler do that RVM does not?

Bunlder will install all gems that are needed by a project (that uses bundler, and have all needed gems specified in a Gemfile). RVM does not do this.

Using the Gemfile you can specify what gem groups (ie: development, testing)...

There are many 'small' things like these that bundler does but RVM does not. In general as the good people above explained, RVM has a different set of goals from that of bundler. RVMs about managing ruby runtimes while bundler is about managing dependent gems for a application.

Answer 3

RVM is more like a containment unit. While Bundler is like a manifest (dependency manager) of what the application will require or use in it's lifecycle (among other things).

If you are working in Rails, you will not be able to escape Bundler. But I use it all the time just so I know what Gems I'll need, and so will others who later come into the project.

RVM helps me separate out my Rubies and then further into Rubies/projects. This way I don't have a slew of Gems and different versions all in one pile.

Not exactly the most action packed answer, but hope it helps a little.

Answer 4

Bundler is a tool for managing dependencies in your code -- i.e., all the gems it requires. It will make sure that all the gems you specify in your Gemfile, and any dependencies, are installed on your system. It doesn't really care which version of ruby you are using, it just installs the gems for you under whichever interpreter is in use.

RVM is a tool for running multiple rubies, and in theory, multiple gemsets as well. It doesn't handle dependencies for you at all -- it's still up to you to install the gems.

My experience (and I'm new to RVM), is that you don't want to bother with RVM unless you have a need for running multiple rubies, or need gems installed for different projects that somehow conflict with each other. Even if you are using RVM, it makes sense to use Bundler to manage gem dependencies so that your Gemfile can be tracked in whatever code repository you are using.