Add support for installing using Nix (zero maintenance)

[srid]

This is an improved version of #73 (and resolves #70) wherein the need to change the version and hash every time the Cargo files change is avoided. Now you can just forget about the .nix files (unless a new C dependency is being introduced).

[balsoft]

Some nitpicks, looks great otherwise!

BTW, maybe you could consider adding .envrc with use flake for those of us who use direnv+nix-direnv.

[srid]

@soywod This PR fails for 0.2.4; I believe that's because Cargo.lock wasn't updated along with the commit that changed Cargo.toml.

Error message,

++ crate2nix generate -f ./Cargo.toml -o Cargo-generated.nix -h /nix/store/i11yfpm336cwlzl3idsxiq6dm067v3cs-himalaya-crate2nix/crate-hashes.json
Error: while retrieving metadata about ./Cargo.toml: Error during execution of `cargo metadata`: error: the lock file /build/vv6c95617dy8c6hxl0qvh32crl7jqpyj-source/Cargo.lock needs to be updated but --locked was passed to prevent this

[soywod]

Ah yes indeed, I bumped the version without launching back cargo build, I will update tomorrow

[srid]

@soywod Since I don't know enough about Nix, I plan to dive in this weekend to understand at least the concept. This way I will understand better what you did and I will be able to merge your work.

By the way, Nix is also useful for non-development purposes, such as wrapping himalaya in conjunction with other tools (pandoc, bat, fzf, etc.) to provide extra workflows, like this one for reading email in CLI:

srid/nixos-config@6362b4d

[balsoft]

Well, you can export a NixOS module that uses home-manager, or a home-manager module (though that's not as standardized).

[srid]

I've created a template repo based on this work: https://github.com/srid/rust-nix-template

[srid]

@balsoft Do you know what the idiomatic way is to add dev-shell Rust dependencies in Nix?

For eg., to make cargo watch available in nix-shell: https://github.com/passcod/cargo-watch

Or certain crate tools available in nix-shell, eg: trunk from https://yew.rs/docs/en/next/getting-started/project-setup/using-trunk

[srid]

@balsoft Do you know of an idiomatic way to override a crate dependency to point to a git fork?

I noticed that Cargo.toml supports this, but we can't use it because the fetch will fail during nix build (due to blocked network access):

# Cargo.toml
postgrest = { git = "https://github.com/srid/postgrest-rs", branch = "notokio" }

I also tried adding something like this to defaultCrateOverrides, but that doesn't work for some reason (build is still using the crate registry's package stored in nix store),

                postgrest = oldAttrs: with pkgs; {
                  src = inputs.postgrest-rs; 
                };

[srid]

Ah. Looks like you have to specifying the source in both places (Cargo.toml and flake input+override); then it works ... mysteriously.

[balsoft]

the fetch will fail during nix build (due to blocked network access):

I thought I fixed this here: nix-community/crate2nix#154 (but only on Nix 2.4)

[srid]

@soywod I believe this PR is ready to be merged anytime.

(I keep merging it with master only because I use this branch directly in my nixos configuration).

[soywod]

❤️ Thanks a lot for your giant contribution guys! Feel free to write an entry in the wiki about Nix (if you judge it necessary, ofc).

[soywod]

In fact, maybe it makes sense to move the Nix section from the README to the wiki, in the Installation section? I would like to keep the README as short and concise as possible (I need to work on it), and to move all the real documentation to the wiki.