direnv for Node and Python

I use direnv to manage per-directory environment variables, which comes in handy when a project needs its own Python or Node (or whatever) environment.

Installation #

Install direnv from apt, brew, or whatever. Then install into your .bashrc like so:

if which direnv &> /dev/null; then
  eval "$(direnv hook bash)"
fi

Node #

One time, install node like the following. I use nodeenv to pull in whatever version I want, but the important thing is the target directory and naming scheme.

nodeenv -n 22.3.0 $HOME/node_versions/node-v22.3.0 --pre-built

Add the following globally (e.g., to .bashrc):

export NODE_VERSIONS=$HOME/node_versions

And then, here's the per-project Node incantation of .envrc:

use node 22.3.0
layout node

See the direnv-stdlib(1) for more details.

Python #

Python is a bit different. Here's the .envrc:

layout python3

It creates the virtualenv for you!

$ which python
[...]/.direnv/python-3.12/bin/python