nishantjr / devbox-play

devbox-play: Experiments with devbox/nix

Working from the source code README.

WARNING: After devbox add … you should exit and restart any devbox shell instances so that they get the new configuration/plugins specific to the package. (refresh in the shell will not work (we guess) because it refreshes only env vars, it does not re-run package hooks or init_hook.)

Installation:

• The curl magic installs a devbox bootstrap binary in /usr/local/bin/; via sudo. This devbox second-stage bootstrap script can just as well go in ~/.local/bin/, though the install script downloaded by curl is hard-coded to use sudo and /usr/local/bin/.
• Our Test script tweaks the above to do a sudo-free install to ~/.local/bin/.
• devbox add will, if /nix/ does not exist, use sudo to create the /nix/ directory and change ownership to the current user (probably), and then attept to a single-user install of Nix 2.18 from releases.nixos.org, giving you a chance to abort first. This uses curl -L https://releases.nixos.org/nix/nix-2.18.1/install | sh -s.

General:

• devbox init creates only a fresh devbox.json in the current working directory (even if it's not the root of the repo); this becomes the "project dir" found even if you subsequently run devbox commands below that directory.
• devbox add asl@latest will create .devbox/ in the project dir; this is ignored by git in a clever way (see below). It also updates devbox.json to change "packages": [], to "packages": ["asl@latest"],, and adds devbox.lock to add the details and Nix IDs of the package. Also seems to create the .devbox/ subdir
• When using a Devbox-installed Python, there is special support to use a project-local create a venv virtual environment (in $VENV_DIR, default .devbox/virtenv/python/.venv) for the project. This is not automatically activated.
  • The automatic creation happens not when you devbox add python but only after you exit and devbox shell again. That runs the helper file .devbox/virtenv/python/bin/venvShellHook.sh which creates it in $VENV_DIR. (This cannot be run stand-alone.)
  • To automatically activate, ; add source $VENV_DIR/bin/activate to the init_hook of devbox.json. (You can also set $VENV_DIR there.)
  • This info can be shown with devbox info python.
  • Various things can cause system Python stuff to leak into the devbox environment if you're not using a Python venv.

Common commands:

• devbox install PKG[@VER]
• devbox info PKG: Shows version and other info, including special Devbox handling of e.g. Python.
• devbox shell: Start a subshell with the devbox environment for the project found from the CWD. Has the usual massive slew of long /nix/store/… paths at the front of $PATH. Use refresh within the shell to do some sort of environment update (but does not re-run init_hook or package hooks).
• devbox shellenv: Prints export commands to update the environment for the Nix profile and all its various packages, adds a refresh alias to re-run the update, and executes hash -r.
• devbox run: Run a single command in the project environment.
• devbox setup nix: ???

Notes:

• Set DEVBOX_DEBUG=1 in the environment to get a verbose log of what devbox is doing, and any errors that result.
• Devbox does not work with:
  • Nix 2.3.7 (Debian 11) due to lack of the --impure flag.
  • Nix 2.8.0 (Debian 12), due to lack of --priority flag on nix profile install
  • Nix 2.18 seems to be the desired version; see above.
  • 2.18 install fails on Debian 12; see below.

Interesting points:

• The $PROJECT_DIR/.devbox/ directory is ignored without having to commit anything to get by creating a .gitignore under that directory containing * and .*.

Errors and Workarounds

Debian 12 Nix 2.18 Install Failure

devbox add asl@latest without a /nix/ directory makes Devbox attempt to install nix (per above), which fails with:

Installing nix with: curl -L https://releases.nixos.org/nix/nix-2.18.1/install | sh -s
This may require sudo access.
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100  4052  100  4052    0     0  32017      0 --:--:-- --:--:-- --:--:-- 31905
downloading Nix 2.18.1 binary tarball for x86_64-linux from 'https://releases.nixos.org/nix/nix-2.18.1/nix-2.18.1-x86_64-linux.tar.xz' to '/tmp/nix-binary-tarball-unpack.SqZ3zIE1Sv'...
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100 20.6M  100 20.6M    0     0  7362k      0  0:00:02  0:00:02 --:--:-- 7365k
Note: a multi-user installation is possible. See https://nixos.org/manual/nix/stable/installation/installing-binary.html#multi-user-installation
performing a single-user installation of Nix...
directory /nix does not exist; creating it by running 'mkdir -m 0755 /nix && chown cjs /nix' using sudo
copying Nix to /nix/store...

installing 'nix-2.18.1'
building '/nix/store/hzx954rnda4k348rb4wvqbdzp9z0ynjy-user-environment.drv'...
error: opening lock file '/nix/var/nix/profiles/per-user/cjs/profile.lock': No such file or directory
/tmp/nix-binary-tarball-unpack.SqZ3zIE1Sv/unpack/nix-2.18.1-x86_64-linux/install: unable to install Nix into your default profile
Error: exit status 1

The problem may be that the …/cjs/ directory above does not exist. It can be created with

mkdir /nix/var/nix/profiles/per-user/cjs

However, re-running Devbox at this point won't work because it thinks that Nix is installed but it is not. So you must manuall re-run the Nix install:

curl -L https://releases.nixos.org/nix/nix-2.18.1/install | sh -s

But the actual problem turns out to be ~/.nix-* files/dirs left behind from a previous Nix install, rm -rf ~/.nix-* fixes the install to work the first time.

However, after that it comes up with:

Nix installed successfully. Devbox is ready to use!
Error: exec: "nix": executable file not found in $PATH

Maybe it's not re-running whatever extra .bash_profile stuff that the Nix install added? I.e., this (line split for clarity):

if [ -e /home/cjs/.nix-profile/etc/profile.d/nix.sh ]; then
  . /home/cjs/.nix-profile/etc/profile.d/nix.sh;
fi # added by Nix installer

Note that this does nothing unless both $HOME and $USER are set in the environment. The dent container I'm using for some reason doesn't have $USER set. This needs investigation.