quickenv: An unintrusive environment manager

direnv is a manager for loading/unloading environment variables per-project. It achieves this by hooking into your shell and executing a shellscript called .envrc upon cd, loading environment variables generated by that shellscript into your current shell. It is useful for automatically activating virtualenvs, for example.

Unfortunately direnv can be a little bit "intrusive" to use. For a start, it runs its own code in your shell. This alone is not noticeable in terms of terminal responsiveness, but the various .envrcs that people end up writing sometimes are. direnv does not have a reliable, out-of-the-box way to cache the execution of .envrcs, as it is arbitrary code, and so it runs everytime you cd in and out of a project.

quickenv is a replacement for direnv. It works with existing .envrcs, and as such is a drop-in replacement, but how you interact with quickenv and how it loads environment variables is fundamentally different.

• quickenv does not hook into your shell. It only requires an addition to your PATH.
• quickenv does not load .envrc when changing directories. Instead you need to initialize quickenv per-project using quickenv reload, and rerun that command everytime the .envrc changes.
• quickenv does not even load environment variables into your shell. Instead it creates shim binaries that dispatch to the right executable.

quickenv is heavily inspired by volta which achieves version management for nodejs by also providing "shim" binaries for the most common commands (yarn, npm, node).

Installation

Install quickenv:

• from GitHub as a standalone binary
• from AUR for ArchLinux, e.g. paru -S quickenv
• or build from source

Then set it up in your shell:

# Into your bashrc/zshrc. This should be at the front of your PATH, such that
# quickenv can shim/shadow binaries effectively.
export PATH=$HOME/.quickenv/bin/:$PATH

# You can remove "direnv hook" from your bashrc/zshrc, but the tool needs to
# stay installed.

Some notes:

• quickenv currently assumes direnv is in your path, in order to load its "standard library".

• quickenv also currently does not have pre-built binaries. You need to install Rust and install it using Rust's package manager, Cargo.

• quickenv assumes a POSIX environment.

Building from source

cargo install quickenv  # latest stable release
cargo install --git https://github.com/untitaker/quickenv  # latest git SHA

Usage

We're going to check out sentry, because that's one of the .envrcs I use. Note that Sentry's .envrc only works on MacOS.

git clone https://github.com/getsentry/sentry
cd sentry

# Execute the .envrc and cache the resulting environment variables in ~/.quickenv/envs/.
# Sentry will prompt you to create a virtualenv, install dependencies via homebrew, etc.
# Re-run this command manually everytime the .envrc changes.
quickenv reload

# As part of executing the .envrc, a virtualenv has been created at './.venv/'.
# There are multiple commands available in '.venv/bin/', such as 'pytest' (a test
# runner), or 'sentry' (the main application).

# 'quickenv shim' makes those commands available in your shell.
quickenv shim

# These commands will now run with the virtualenv enabled.
sentry devserver --workers
pytest tests/sentry/

Advanced usage

# Alternatively you can shim commands explicitly. Be careful: Any command you
# missed (such as 'python' or 'pip') would run outside of the virtualenv!
quickenv shim sentry pytest

# You can also run commands within the current .envrc without shimming them.
quickenv exec -- pytest

# Your git hooks don't execute in the virtualenv for some reason? Just replace
# git with a binary that itself loads the virtualenv.
quickenv shim git

# Actually activate the virtualenv in your current shell. `quickenv vars`
# prints all the extra environment variables with which each shimmed binary runs.
set -o allexport
eval "$(quickenv vars)"
set +o allexport

# Or alternatively, substitute your shell with one where your .envrc is loaded
exec quickenv exec $SHELL

# Or shim 'bash', so that when you open a subshell, the virtualenv is activated.
quickenv shim bash

# Or shim 'make', so your Makefile runs in the virtualenv.
quickenv shim make

# Curious which binary is actually being executed?
which make
# --> /home/user/.quickenv/bin/make
quickenv which make
# --> /usr/bin/make
quickenv exec which make
# --> /usr/bin/make

# Or for general debugging, increase the log level:
QUICKENV_LOG=debug make
# [DEBUG quickenv] argv[0] is "make"
# [DEBUG quickenv] attempting to launch shim
# [DEBUG quickenv] abspath of self is /home/user/.quickenv/bin/make
# [DEBUG quickenv] removing own entry from PATH: /home/user/.quickenv/bin
# [DEBUG quickenv] execvp /usr/bin/make
# ...

Command Reference

An unintrusive environment manager

Usage: quickenv <COMMAND>

Commands:
  reload  Execute .envrc in the current or parent directory, and cache the new variables
  vars    Dump out cached environment variables
  shim    Create a new shim binary in ~/.quickenv/bin/
  unshim  Remove a shim binary from ~/.quickenv/bin/
  exec    Run a program with .envrc loaded without having to shim it
  which   Determine which program quickenv's shim would launch under the hood
  help    Print this message or the help of the given subcommand(s)

Options:
  -h, --help     Print help
  -V, --version  Print version

Environment variables:
    QUICKENV_LOG=debug to enable debug output (in shim commands as well)
    QUICKENV_LOG=error to silence everything but errors
    QUICKENV_NO_SHIM=1 to disable loading of .envrc, and effectively disable shims
    QUICKENV_SHIM_EXEC=1 to directly exec() shims instead of spawning them as subprocess. This can help with attaching debuggers.
    QUICKENV_NO_SHIM_WARNINGS=1 to disable nags about running 'quickenv shim' everytime a new binary is added
    QUICKENV_PRELUDE can be overridden to customize the shell code injected before executing each envrc. By default, quickenv loads ~/.config/direnv/lib/*.sh files and then runs 'eval "$(direnv stdlib)"' to mimic direnv's behavior.

License

Licensed under MIT, see LICENSE.