asdf is a general purpose version manager that can manage versions of most programming language runtimes through a set of plugins.

With micro-services being all the rage and the ever changing landscape of the development world, it is rare to utilize a single version of language runtime. Even when you want to upgrade from one to the other you'll need both usable on your system at the same time.

I've used tools like pyenv and nvm in the past when I needed to change versions depending on which project I'm contributing to. But with asdf you have one tool to rule them all!

Getting Started

The first thing you need to do when working with asdf is grab the plugins for the languages you are interested in working with. You can list what plugins are available:

> asdf plugin list all
golang                       *https://github.com/kennyp/asdf-golang.git
golangci-lint                 https://github.com/hypnoglow/asdf-golangci-lint.git
nodejs                       *https://github.com/asdf-vm/asdf-nodejs.git
poetry                       *https://github.com/asdf-community/asdf-poetry.git
python                       *https://github.com/danhper/asdf-python.git
yarn                         *https://github.com/twuni/asdf-yarn.git

On the left will be the name of the plugin and on the right will be the repository where it lives. It'll me marked with an asterisk if you already have it installed.

To install a plugin you say asdf plugin add <plugin> to get it installed. You can also provide the repository where you want it pulled from, for example:

> asdf plugin add nodejs https://github.com/asdf-vm/asdf-nodejs.git
> asdf plugin add python https://github.com/danhper/asdf-python.git

This will not give you any version of those languages, it is only installing the plugin that knows how to work with those languages. You are ready to pull down any versions you want at that point:

> asdf install nodejs 14.19.0
> asdf install python 3.9.10

Once you have the versions installed you will be able to view them like this:

> asdf list
golang
  1.17.7
nodejs
  --help
  12.22.10
  14.19.0
  16.14.0
  17.5.0
poetry
  1.1.13
python
  3.9.10
yarn
  1.22.17

Using the installed languages

To activate a specific version of a language you have you have three options:

Make it global

You can make it global, meaning when you run the tool like python it'll use this version for the system:

> asdf global python 3.9.10

Make it local

You can make it local, which means it will generate a file in the current directory named .tool-versions and so whenever you change into a directory it will activate the versions defined in there.

> asdf local nodejs 12.22.10
> cat .tool-versions 
nodejs 12.22.10

The great thing about this is you can commit that file to git and then anyone who checks out the project and uses asdf will have the same versions activated!

Temporary

If you want to activate a version of a language temporarily you can swap to it for the current shell:

> asdf shell golang 1.17.7
> env|grep -i ASDF
ASDF_GOLANG_VERSION=1.17.7

It sets an environment variable that will have preference over the file. If you ever wonder what versions a directory is using you can run:

> asdf current
golang          ______          No version set. Run "asdf <global|shell|local> golang <version>"
nodejs          12.22.10        .tool-versions
poetry          ______          No version set. Run "asdf <global|shell|local> poetry <version>"
python          3.9.10          .tool-versions
yarn            1.22.17         .tool-versions

Conclusion

asdf is an AWESOME tool to utilize if you find yourself using many different languages or many different versions of the same language. You should check it out and see if it can improve your workflow.