asdf: a version manager to rule them all

We keep using more and more programming languages, and we need to control their versions. Enter asdf!

Written in Development by Marc Riera — February 13, 2020

When I started programming in Ruby, I had to install rvm (Ruby Version Manager) to use the correct Ruby version for each of the different projects I was in. After some time, I switched to rbenv (yes, that's another Ruby version manager) because rvm was too slow. but then a workmate appeared, saying chruby (you guessed it, yet another Ruby version manager) was even faster, so I switched again. All was good, flowers were blooming, rainbows appeared in the sky and butterflies... Butterflied? Butterflew? Well, whatever, butterflies did their thing.

Then NodeJS appeared and, of course, I had to install its own version manager. I went with nvm (Node Version Manager), but then I switched laptops and I tried n, a lighter version manager. I had some problems with it, so I finally went back to nvm. Butterflies started getting worried.

Then I started programming in Elixir. Guess my next step.

At this point, butterflies got sad and stopped butterflying.

This setup is not sustainable, for me. I need to keep remembering how to install new language versions, and when setting up a project I need to remember what files each of the version managers use to define what version this project uses. Oh, and I need to actually install all the needed version managers, and you'd probably want to set the version autodiscovery, so you always run the correct language version when changing projects...

"But Marc, you only need to install a new version once in a while, and you can set a project template that adds all the needed files", you might say. And you'd be right, it's not a big deal. But (of course there was a "but", otherwise this post would not make sense) this forces all devs in the project to install a version manager for each of the languages we need, and manually install the correct versions. This doesn't scale well.

Can we do better? Of course we can.

Enter asdf!

Managing the managers

asdf is a version manager version manager. No, that's not a typo! With asdf you install language version managers, and it offers a common syntax to install language versions:

asdf plugin-install elixir
asdf plugin-install ruby
asdf install elixir latest
asdf install ruby 2.7.0

See? I don't even need to know what version managers it uses, internally. And in your project you can setup the project language versions like this:

# .tool-versions
ruby 2.7.0
node 12.8
elixir 1.4.0

When cding to this project, asdf will automatically set the correct versions for you. And the best thing is that, if some workmate enters the project and they don't have the dependencies installed they can run this command:

asdf install

And asdf will install all the needed managers and versions! You can see the list of plugins here. Be sure to check the official docs for other useful commands!

Switching to asdf

Switching all your projects to asdf, though, might be a little tiring. And maybe not everyone in the team will want to use it (yet). In these cases, asdf lets you fallback to legacy version files, so that managers that support it fallback correctly (e.g. the .ruby-version file for rbenv):

# ~/.asdfrc
legacy_version_file = yes

Wrapping up

I hope you see the advantages of using asdf in your local machine. It's been a game changer for me, and since I installed it I haven't had any problem remembering how to install new language versions or how to change them.

Thanks for reading!

Photo by Kaung Myat Min on Unsplash

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