Execute shellHook on cached runs

[colemickens]

I set PS1 in the shellHook of my flake.nix (which I think isn't terrible).

However, after #91 is merged, I think this is ineffective because my shell is basically always cached...

Is there anyway to run shellHook in cached hit cases? Or if not, could there be another attribute that is always read out and executed?

[colemickens]

Well, it seems like direnv blocks this anyway.

[Mic92]

Potentially you could source the cache after use flake?

eval "$(< "$profile_rc")"
eval $shellHook

or just use .envrc to run some commands.

[johnae]

It seems to me as if #91 broke https://github.com/numtide/devshell which is unfortunate. Personally I have a simpler take on devshell that works in a similar fashion and that is now broken too. I believe the relevant part of devshell is this:

https://github.com/numtide/devshell/blob/ab14b1a3cb253f58e02f5f849d621292fbf81fad/nix/mkNakedShell.nix#L44

It could be something with my setup that's wrong but it seems I started having problems after ugrading to 1.5.0. @zimbatm could perhaps comment on this as he's the author of devshell.

[johnae]

At least I can confirm that deleting this line:

nix-direnv/direnvrc

Line 155 in d26fc52

sed -i "/eval \"\$shellHook\"/d" "$profile_rc"

makes https://github.com/numtide/devshell work again. What I mean by "not working" is that none of the packages that are supposed to be made available in the environment are.

[johnae]

In my case I was able to avoid the issues I experienced by not doing anything "important" in the shellHook so for me this is not a problem anymore.

[johnae]

@ryneeverett @Mic92 I believe departing from the behavior of nix develop has made nix-direnv unusable with https://github.com/numtide/devshell. I don't think nix-direnv is doing the right thing here.

[Mic92]

This PR enables shellHook for both use_nix and use_flake, even in cached runs
It requires nix2.4 though:

#125
I might hold of a release until at least the next nixos version is released and only
publish a release candidate before.

[lilyball]

I keep running into this too. I have my own equivalent of numtide/devshell (I didn't know about devshell until now, it sounds like it's a much more comprehensive solution) and the fact that $shellHook isn't evaluated on cached runs means I end up with the wrong environment.

@Mic92 I haven't tried the PR, since I don't want to try and shift my config over to pulling patches from GitHub. Given that Nix 2.4 is the stable nix in nixpkgs now, is there a reason not to go ahead and publish a release with this new change? By default a new release won't end up on any existing release channels, so there shouldn't be any concerns there.

[Mic92]

I keep running into this too. I have my own equivalent of numtide/devshell (I didn't know about devshell until now, it sounds like it's a much more comprehensive solution) and the fact that $shellHook isn't evaluated on cached runs means I end up with the wrong environment.

@Mic92 I haven't tried the PR, since I don't want to try and shift my config over to pulling patches from GitHub. Given that Nix 2.4 is the stable nix in nixpkgs now, is there a reason not to go ahead and publish a release with this new change? By default a new release won't end up on any existing release channels, so there shouldn't be any concerns there.

The PR is not ready quite yet.

[nova-nowiz]

Is there a quickfix for that in the meanwhile?
I tried using the nix-2.4 branch as an overlay to nix-direnv but that didn't work (probably my fault here 😄, or maybe it should be an overlay on nix-direnv-flakes?)

[Mic92]

Is there a quickfix for that in the meanwhile? I tried using the nix-2.4 branch as an overlay to nix-direnv but that didn't work (probably my fault here smile, or maybe it should be an overlay on nix-direnv-flakes?)

I am using it by sourcing it manually but atm the caching does not work: https://github.com/Mic92/dotfiles/blob/0e30755334eb53e4cbcfe49453b6bf18e3d581c2/home/.direnvrc#L3

[rraval]

Is there a quickfix for that in the meanwhile?

I've added an extra line to my .envrc under use flake

use flake
eval "$shellHook"  # quotes are important here

It seems to do the right thing but I've only looked at it superficially and moved on (so I can't comment on whether this is the "right" workaround and what the cons might be).

[nova-nowiz]

Thanks for both solutions!
That really helps 😉

[bbenne10]

2.0 should handle this case nicely. Please open a new issue if you find some problem with that line. Thank you!