devenv removes itself during garbage collection

[DriesCruyskens]

Describe the bug
After running devenv gc in a project that has been initialised by devenv. The devenv command is not available anymore and has to be reinstalled.

To reproduce

$ devenv gc
✔ Removing non-existing symlinks in /Users/driescruyskens/.local/share/devenv/gc ... in 0.0s.
• Found 13 active environments.
• Deleted 36 dangling environments (most likely due to previous GC).
warning: Your daemon version is too old to support garbage collecting a closure, falling back to a full gc
✔ Running garbage collection (this process may take some time) ... in 6.4s.

• Done. Successfully removed 2 symlinks in 6.3727255s.
$ devenv shell
zsh: command not found: devenv

This happens even in a freshly initialised devenv project.

Version

devenv 1.0.8 (aarch64-darwin)

[sandydoo]

How is (or was) devenv installed on this machine?

[DriesCruyskens]

Using the following commands:

$ sh <(curl -L https://nixos.org/nix/install)
$ nix-env -iA devenv -f https://github.com/NixOS/nixpkgs/tarball/nixpkgs-unstable

[sandydoo]

Strange! nix-env installs things to a profile (~/.nix-profile), which should be protected from garbage collection.

A couple of things to check:

1. nix-env -q. Is devenv still listed? Is devenv available if you open a new shell?
2. What if we take devenv out of the equation and just run nix-store --gc or nix store gc? Does that also delete devenv?

[DriesCruyskens]

• nix-env -q does not list devenv. devenv is not available when opening new shell.
• nix-store --gc also removes devenv

When I follow all the symlinks of my nix profile. /Users/driescruyskens/.nix-profile -> /Users/driescruyskens/.local/state/nix/profiles/profile -> profile-1-link -> /nix/store/y9hqy0x0rrdhsz2qkfmyrw6l62lgxhvw-user-environment. Notice this last one is removed during gc:

$ nix-store --gc
finding garbage collector roots...
deleting garbage...
deleting '/nix/store/y9hqy0x0rrdhsz2qkfmyrw6l62lgxhvw-user-environment' # <- should this be removed in gc?
deleting '/nix/store/xp5636bdvww7nbcmj9ymrghg6b9skm67-devenv-1.0.8.drv'
deleting '/nix/store/d8z3qwsk69ccqwi5b7wkn27qmkj59vb6-cachix-1.7.4.drv'
deleting '/nix/store/xp6jr77acv1n1y0iadbhm52frarpzw76-dhall-1.42.1.drv'
deleting '/nix/store/szd5h9bnrhxf34p4dxj4f24nwlz7wjwf-cachix-api-1.7.4.drv'
deleting '/nix/store/yqa3dx4jrnapwms6chvd88k3ppwhxcni-swagger2-2.8.9.drv'
deleting '/nix/store/bzc0i86k11ydpclgqcnzcq60y5fag3cw-user-environment.drv'
deleting '/nix/store/m9fb339s5l3631k6mnc52j15lmy42y9y-env-manifest.nix'
deleting '/nix/store/j8qgrzwxaxikw111n0iqbc473jvg9ggc-devenv-1.0.8'
deleting '/nix/store/90rq091pmn9ijrqgablkk0gzvhxi98xh-cachix-1.7.4-bin'
deleting '/nix/store/79yns69mv7y53a3qjl20a2mf6c6128rf-servant-conduit-0.16.drv'
deleting '/nix/store/spr6bawk3gzbpp4cqd3kbdx568qy52n4-servant-client-0.20.drv'
deleting '/nix/store/rg4yx0rnvxji1dspmhqss55ln9bwv240-servant-server-0.20.drv'
deleting '/nix/store/lnaawr42l8ix04m62cd50y8ycirc11ka-wai-app-static-3.1.9.drv'
deleting '/nix/store/dr9gccblgfflaqghpjnrzfvq81r7v7pa-hspec-wai-0.11.1.drv'
deleting '/nix/store/sgyyj2g62ndpk6nrh061v5b714l3j1n8-wai-extra-3.1.15.drv'
deleting '/nix/store/2d8vgsy0qc50bw4zdv5p9qld0w7i5gy1-warp-3.3.31.drv'
deleting '/nix/store/qlz4xkkw15zy02hjldqpyqfqa4fcx9zq-http2-5.0.1.drv'
deleting '/nix/store/1yn3crf6cdwmq2yn3046fx0w668rv24g-cborg-json-0.2.6.0.drv'
...

[sandydoo]

So, we've narrowed it down to an issue with Nix. No, the user-environment should not be deleted in this case. That profile link should be a GC root, preventing it from being GC'd.

nix-store -q --roots /nix/store/y9hqy0x0rrdhsz2qkfmyrw6l62lgxhvw-user-environment

Normally, this query should return something like /Users/driescruyskens/.local/state/nix/profiles/profile/profile-1-link -> /nix/store/y9hqy0x0rrdhsz2qkfmyrw6l62lgxhvw-user-environment, confirming that the path is protected from GC. I'm not sure what has gone wrong here.

[sandydoo]

Assuming it's an installation issue, you could give the alternate installer (or the detsys one from which it's forked) a try. These are far better on all fronts, and particularly so for macOS.

I won't have the internet bandwidth to try to replicate this in a fresh VM for at least the next week. IPSWs are large. But it would be good to figure out what went wrong here 🤔

[DriesCruyskens]

Running nix-store -q --roots /nix/store/y9hqy0x0rrdhsz2qkfmyrw6l62lgxhvw-user-environment returned an empty document. I was indeed able to fix the issue by uninstalling and using detsys installer. Thanks for your time on this great project!

[MalteMagnussen]

Maybe not related, but what does this mean: warning: Your daemon version is too old to support garbage collecting a closure, falling back to a full gc

Full:

mhm@mhm:~/Documents/asset-search/search$ devenv gc
✔ Removing non-existing symlinks in /home/mhm/.local/share/devenv/gc ... in 0.0s.
• Found 62 active environments.
• Deleted 0 dangling environments (most likely due to previous GC).
warning: Your daemon version is too old to support garbage collecting a closure, falling back to a full gc

I'd have liked to open a discussion on this, but unless I'm blind, this repository does not have discussions.

My shell was not deleted during the gc btw. Only took 11.5s to enter it again. Whereas a fresh shell took minutes to build.

[sandydoo]

what does this mean: warning: Your daemon version is too old to support garbage collecting a closure, falling back to a full gc

@MalteMagnussen, this has been fixed in v1.1.

It's an innocuous message that Nix is doing a GC run of the entire store, instead of checking just the shell environments we've asked it to check. In other words, this translates to "hang on, this is going to take a while".
AFAIK, you'd always see this message because the closure GC patches weren't quite layered correctly.

I'd have liked to open a discussion on this, but unless I'm blind, this repository does not have discussions.

We have a pretty active Discord for these things.