x52 Nix

Shared Nix packages and Just fragments for x52 projects.

Packages

x52-just

Contains reusable Just fragments. The package currently exports rust.just, which defines:

• msrv: the lowest rust-version declared by a Cargo workspace member, normalized to three components; for example, 1.82 becomes 1.82.0.
• msrv_rustup: the same version prefixed with + for rustup-aware Cargo commands; for example, +1.82.0.

The lookup uses cargo metadata --no-deps, ignores non-workspace packages, and fails if Cargo metadata cannot be read or no workspace member declares rust-version.

x52-release-tools

Contains release-plz post-processing commands:

• x52-bump-changelogs checks out a release-plz pull request, adds the released versions to crate changelogs, updates README version links, and pushes a commit when anything changed.
• x52-update-release-notes copies the matching changelog sections into GitHub releases.
• x52-comment-release-pr adds or updates a draft-release link comment on the merged release pull request.
• x52-comment-release-assets-uploaded adds or updates a comment after the release assets are uploaded.

The commands expect cargo to already be available. Git, GitHub CLI, jq, and the required shell utilities are supplied by the Nix package.

Usage

Build the Just package to a stable project-local link:

nix build github:x52dev/nix#x52-just --out-link .x52-just

Add .x52-just to the consuming project's .gitignore, then import the fragment from its justfile:

import '.x52-just/rust.just'

show-msrv:
    @echo {{msrv}}

check-msrv:
    cargo {{msrv_rustup}} check --workspace

The consuming environment must provide just, cargo, and jq. The msrv_rustup form also expects a rustup-managed toolchain.

Flake-parts module

flakeModules.default and flakeModules.justRust provide x52.justRust.shellHook. Add it to a development shell to create an ignored .toolchain/rust.just symlink when the shell starts. The module does not select or add a just package.

imports = [ inputs.x52.flakeModules.default ];

perSystem = { config, pkgs, ... }: {
  devShells.default = pkgs.mkShell {
    packages = [
      pkgs.cargo
      pkgs.just
    ];

    shellHook = config.x52.justRust.shellHook;
  };
};

For an existing hook, append config.x52.justRust.shellHook to it. Set x52.justRust.directory in perSystem when a project needs another directory.

The shell hook runs for nix develop, direnv, and the nicknovitski/nix-develop GitHub Action. Add the directory to .gitignore:

/.toolchain/

To pin this repository in a consuming flake, add it as an input:

inputs.x52 = {
  url = "github:x52dev/nix";
  inputs.nixpkgs.follows = "nixpkgs";
  inputs.flake-parts.follows = "flake-parts";
};

With flake-parts, re-export x52-just or add the release tools to a development shell:

perSystem = { pkgs, inputs', ... }: {
  packages.x52-just = inputs'.x52.packages.x52-just;

  devShells.default = pkgs.mkShell {
    packages = [
      inputs'.x52.packages.x52-release-tools
    ];
  };
};

Create the local Just link from the pinned input with:

nix build .#x52-just --out-link .x52-just

Just import paths are relative to the importing file, so run the command from the project root and keep the out-link alongside the root justfile.

For GitHub Actions, enter the development shell before invoking the release commands:

- name: Enter Nix devshell
  uses: nicknovitski/nix-develop@9be7cfb4b10451d3390a75dc18ad0465bed4932a # v1.2.1

Pass release-plz output through RELEASE_PLZ_PR_JSON or RELEASE_PLZ_RELEASES_JSON, and provide GH_TOKEN for GitHub mutations.

The commands use fixed x52- HTML markers. They make retries update the existing comment instead of creating another one:

x52-comment-release-pr "$RELEASE_PLZ_RELEASES_JSON"
x52-comment-release-assets-uploaded "$RELEASE_PLZ_RELEASES_JSON"

Both commands accept an optional second argument for the merge commit SHA. Without it, they use GITHUB_SHA.

Development

Enter the development shell with nix develop or use direnv with the included .envrc.

just fmt
just check
nix build .#x52-just
nix build .#x52-release-tools