Make it possible to not rebuild deploy-rs

[Flakebi]

Use the deploy-rs from the final packages set. This can avoid rebuilding deploy-rs when using it in a nixos config. It can use the version cached in nixpkgs.

Also add instructions to the readme on how to craft an overlay that uses nixpkgs deploy-rs.

This should fix #163.

[rvem]

Thanks!

[Stunkymonkey]

I am seeing the checks are disabled. Is this intentional? Or does it not make sense?

[rvem]

Is this intentional?

Hmm, not really, not sure why checks weren't triggered for external contributor PR

[wmertens]

@Flakebi question, how does this overlay work? So there's the overlay from the flake and then there's this expression:

  (self: super: { deploy-rs = { inherit (pkgs) deploy-rs; lib = super.deploy-rs.lib; }; })

the way I read the spec is that this function should return an attrset of packages, however it's returning {deploy-rs; lib} as a "package". Is this an undocumented feature of overlays?

[Flakebi]

There is nothing undocumented There is no hidden feature of overlays here.
The “package”, which is actually a set, not a derivation, as you noticed, is the structure defined in this flake.
The overlay defines the same set as this flake, keeping the lib attribute intact and overriding the deploy-rs attribute, which is the actual package.

This structure is defined here in the flake:

deploy-rs/flake.nix

Lines 31 to 42 in 724463b

	deploy-rs = {
	deploy-rs = final.rustPlatform.buildRustPackage (darwinOptions // {
	pname = "deploy-rs";
	version = "0.1.0";
	src = ./.;
	cargoLock.lockFile = ./Cargo.lock;
	}) // { meta.description = "A Simple multi-profile Nix-flake deploy tool"; };
	lib = rec {

[wmertens]

Thank you for the clarification. That's mighty confusing 😅

[teutat3s]

Thank you for this!

Is there a way to make this work when deploy host system != target host system? Currently the overlay is hard-coded to x86_64-linux and that causes an "exec format error" when trying to deploy to a aarch64-linux host.

Or is using the flake the only way in such a case?

[rvem]

Is there a way to make this work when deploy host system != target host system?

I think the only viable way at the moment is to use --remote-build if the target server is powerful enough to perform the profile rebuild