Wednesday, January 31, 2018

Ruby on openSUSE

Ruby is a wonderful programming language. Every year in December as a kind of Christmas present there is a new release. It's great to be on a language which is kept up to date but it comes with the challenge to manage multiple Ruby versions. There are a couple of solutions around such as RVMrbenv, or chruby but they all have their drawbacks.

What would a Linux distribution do? At openSUSE, we package all the versions in the Build Service. We also package many gems but this is an effort which is sort of futile given the huge and growing number of gems and their versions. But you do reliably get the Ruby interpreter and gem tool as openSUSE package. To not create conflicts all the executables are suffixed with the Ruby version. That allows for parallel installation of multiple Ruby versions. It also works for all the executables installed through gems. The drawback is that you don't get the executable names you would expect because of the additional suffix.

So how does the ideal solution look like? We want the distribution maintained interpreter packages, the co-installability of multiple Ruby versions, the native executable names, and the full power of gem.

There is a nice solution to that. It looks like this:

Native executable names can be achieved by creating symbolic links in the bin directory of the user for the tools which come with the Ruby package: ruby, gem, erb, and rake.

Setting the GEMHOME environment variable to a directory in the user's home nicely isolates installation of gems. Parallel versions are handled by gem anyway. You don't need root to install gems and you can easily get rid of an installation if needed.

By setting `install: --no-format-executable` in your .gemrc you get executables with their native names in the GEMHOME directory. So you only have to set the PATH environment variable to let your shell pick them up so that you can call bundle, rspec, etc as it's meant to be.

All this needs a little bit of setup work. To make this easier we have created a tool for openSUSE to manage this for you. It's called orr.

With orr you can just do `orr install 2.4` and it installs the required packages, creates the links, and configures the environment variables so that you can use Ruby 2.4 right away. That works for any other version as well of course.

This setup brings you the best of both worlds, Ruby and openSUSE. Enjoy. And provide feedback.

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