Flox doesn’t set environment variables I declare in a project-level flox.nix. Here’s my customized flox.nix after running flox init --template project:
And outputs of commands that should give an idea of the problem.
❯ flox init --template project
Found git repo: /home/taohansen/Downloads/projects/mothers_emblems
wrote: /home/taohansen/Downloads/projects/mothers_emblems/flake.nix
wrote: /home/taohansen/Downloads/projects/mothers_emblems/flox.nix
Run 'flox activate' to enter the environment.
mothers_emblems on main [✘!+?] is 📦 v0.1.0 via 🐍 v3.10.10 took 8s
❯ flox install python311
Installed 'python311' package(s) into '.#default' environment.
mothers_emblems on main [✘!+?] is 📦 v0.1.0 via 🐍 v3.10.10 took 4s
❯ flox activate
mothers_emblems on main [✘!+?] is 📦 v0.1.0 via 🐍 v3.11.2
❯ exit
exit
mothers_emblems on main [✘!+?] is 📦 v0.1.0 via 🐍 v3.10.10 took 15s
❯ flox activate
mothers_emblems on main [✘!+?] is 📦 v0.1.0 via 🐍 v3.11.2
echo $LANG
en_DK.UTF-8
mothers_emblems on main [✘!+?] is 📦 v0.1.0 via 🐍 v3.11.2 took 3s
❯ exit
exit
mothers_emblems on main [✘!+?] is 📦 v0.1.0 via 🐍 v3.10.10 took 1m22s
❯ flox activate
mothers_emblems on main [✘!+?] is 📦 v0.1.0 via 🐍 v3.11.2
❯ echo $PATH
/home/taohansen/Downloads/projects/mothers_emblems/.flox/envs/x86_64-linux.default/bin:/home/taohansen/.local/share/flox/environments/worldofgeese/x86_64-linux.default/bin:/home/taohansen/.nix-profile/bin:/nix/var/nix/profiles/default/bin:/home/taohansen/.local/bin:/usr/local/sbin:/usr/local/bin:/usr/bin:/var/lib/flatpak/exports/bin:/usr/bin/site_perl:/usr/bin/vendor_perl:/usr/bin/core_perl:/var/lib/snapd/snap/bin:/home/taohansen/bin:/home/taohansen/.garden/bin
mothers_emblems on main [✘!+?] is 📦 v0.1.0 via 🐍 v3.11.2 took 7s
❯ echo $PYTHONPATH
It’s odd because I’m just coming back to Flox after a few weeks where I may have hallucinated this all working
Hey thanks for the report, I’ll see if I can help debug a bit.
You’re right that with the flox.nix file you’ve written LANG should be set to en_US.UTF-8 inside the environment.
I’ll start by trying to reproduce the issue, so getting a bit more info about your shell and “rc script” would help me investigate.
My immediate suspicion is that a profile script such as ~/.bashrc or ~/.zshrc is likely setting LANG after flox activate runs its profile setup. If you could share any relevant snippets from any ~/.profile or “rc scripts” related to LANG settings that would be a big help.
Thanks! It’s not just LANG, PYTHONPATH returns empty when it should be returning $PYTHONPATH:$PWD/__pypackages__/3.11/lib. Neither my .bashrc or .profile are setting any of these values.
One thing I caught was that you were trying to use $PWD when declaring a shell variable.
One important behavior to take note of is that these variables are set “literally”, so no shell expansion is performed.
Here’s an example:
$ mkdir /tmp/example;
$ cd /tmp/example;
$ flox init -t project -i;
$ cat <<'EOF' > ./flox.nix;
{
environmentVariables.LANG = "en_US.UTF-8";
environmentVariables.GOOD = toString ./.;
environmentVariables.BAD = "$PWD";
shell.hook = ''
echo "LANG: $LANG" >&2;
echo "GOOD: $GOOD" >&2;
echo "BAD: $BAD" >&2;
'';
}
EOF
# re-render environment since we manually modified it:
$ EDITOR=cat flox edit -e '.#default';
# To prove that LANG gets set we'll use a junk value in another shell:
$ bash -c "export LANG=xxxx; . <( flox activate -e '.#default'; );";
LANG: en_US.UTF-8
GOOD: /tmp/example
BAD: $PWD
Are you by any chance using direnv?
There might be additional hooks being executed there.
{
# Run shell hook when you enter flox environment
shell.hook = ''
PYTHONPATH="$PYTHONPATH:$PWD/__pypackages__/3.11/lib";
PATH="$PATH:$PWD/__pypackages__/3.11/bin";
'';
packages.nixpkgs-flox.python311 = { };
}
```sh
then activated my Flox environment
mothers_emblems on main [✘!+?] is 📦 v0.1.0 via 🐍 v3.10.10
❯ flox activate
which returned an empty PYTHONPATH
mothers_emblems on main [✘!+?] is 📦 v0.1.0 via 🐍 v3.11.2
❯ echo $PYTHONPATH
I appreciate your patience with me! You didn’t have to help but you did
I did not use flox edit but it looks like that’s gone some way to helping! PATH and PYTHONPATH are still not performing expansions but they are being populated
mothers_emblems on main [✘!+?] is 📦 v0.1.0 via 🐍 v3.11.2
❯ echo $PYTHONPATH
:/home/taohansen/Downloads/projects/mothers_emblems/__pypackages__/3.11/lib
@aameen I saw you wrote a reply yesterday but it evaporated as quickly as it appeared. Was that a mistake or was there more research necessary? Happy to try any changes.
I had written a recommendation about escaping ${FOO} style variable expansion in your flox.nix file, but after re-reading your post I realized that wasn’t the issue.
I think I know why PYTHONPATH is not populating and need to cook up a nice explanation and example to teach you how to fix it. Just to help confirm my suspicion, in your source tree do you currently have a <PROJECT-ROOT>/__pypackages_/3.11/lib directory containing modules?
Also could you confirm that PATH was fixed by my previous recommendation?
One thing you can try changing in your setup hook is to only add “:” if PYTHONPATH is already set.
Right now you’re getting :<PROJECT-ROOT>/__pypackages__/3.11/lib which may cause issues.
You can use the following. Just to help debug I’ll add a few extra prints:
I saw you wrote a reply yesterday but it evaporated as quickly as it appeared. Was that a mistake or was there more research necessary? Happy to try any changes.