Some crates.io hashes cannot be found in Cargo.lock

[YPares]

I'm running into this:

Running phase: unpackPhase
@nix { "action": "setPhase", "phase": "unpackPhase" }
unpacking source archive /nix/store/qc74kg08frlgdjb5fjmwgvb0snpf45lx-unarchiver
source root is unarchiver
Running phase: buildPhase
@nix { "action": "setPhase", "phase": "buildPhase" }
++ crate2nix generate -f ./Cargo.toml -o Cargo-generated.nix -h /nix/store/2mwh4sn153gar2r2ay6x43l7752pr3v3-rustnix-crate2nix/crate-hashes.json
Did not find all crates.io hashes in Cargo.lock. Hashes for e.g. addr2line 0.24.2, adler 1.0.2, adler2 2.0.0, aho-corasick 1.1.3, android-tzdata 0.1.1, android_system_properties 0.1.5, async-channel 2.3.1, async-stream 0.3.6, async-stream-impl 0.3.6, async-trait 0.1.83 are missing.
This is probably a bug.
Prefetching    1/379: https://static.crates.io/crates/encoding_rs/encoding_rs-0.8.35.crate
Error: while prefetching crates for calculating sha256: While spawning 'nix-prefetch-url https://static.crates.io/crates/encoding_rs/encoding_rs-0.8.35.crate --name encoding_rs-0.8.35': No such file or directory (os error 2)
crate2nix failed.

It's difficult to make a minimal reproduction but just in case is it a known error? I tried running cargo update but that doesn't change anything.

[danieldk]

You are bumping into this issue because, most likely, you have git dependency in Cargo.toml. crate2nix will try to determine the crate's hash by downloading the crate using nix-prefetch-git. However, nix-prefetch-git is not added as a dependency to the generatedCargoNix derivation. However, adding it is not going to help you much, since crate2nix runs in a sandbox, so it cannot fetch the crate over the network anyway.

The solution is to run crate2nix in your Rust source folder once. This will create a crate-hashes.json file that contains the fixed-output derivation hashes for the Rust crates that are fetched using git. Add this file to your Nix repo/flake and crate2nix will use it (and not attempt to call nix-prefetch-git).

[YPares]

@danieldk Thanks! I'll try that. I suppose then that I should re-run crate2nix manually everytime a git-provided crate has to change?
I'm not sure it's part of crate2nix documentation, could it be added? I think notable here: https://nix-community.github.io/crate2nix/00_guides/31_auto_generating/