Add support for installing cargo packages in Brewfile

[leighmcculloch]

Verification

• This issue's title and/or description do not reference a single formula e.g. brew install wget. If they do, open an issue at https://github.com/Homebrew/homebrew-core/issues/new/choose instead.

Provide a detailed description of the proposed feature

Add support for installing cargo crates in Brewfile. Include the ability to specify cargo crates in the Brewfile.

For example:

brew "tree"
brew "node"
rust "cargo-expand"

The Brewfile already supports a variety of installation types, with mas, cask, vscode, and most recently go (#20645).

Tooling written in Rust and published to crates.io is available via the cargo install --locked <crate> command. It'd be convenient if the Brewfile bundled and ensures rust applications were installed too.

What is the motivation for the feature?

To expand the convenience of Brewfile so that it manages the bundling / setting up of more applications.

How will the feature be relevant to at least 90% of Homebrew users?

Rust is a common language for so much tooling. When moving between machines it's so helpful that Brewfile manages the programs a developer expects to have on hand, but any tooling that exists in the cargo/rust ecosystem cannot be installed via Brewfile.

What alternatives to the feature have been considered?

Not do this. Manage the installation of rust/cargo tools manually or via some other means.

[leighmcculloch]

To answer some questions from https://docs.brew.sh/Brew-Bundle-and-Brewfile#adding-new-packages-support:

be able to install software without user interaction

👍🏻 The cargo install command has no user interaction.

be able to check if software is installed

👍🏻 There are a couple options for how to do this.

The first option is we can run cargo install --list, and that'll give a list of all the programs that are installed and their versions. But the output of that command is only in a text format in the paragraph.

The other option is we can check if the CARGO_HOME environment variable is set and if not assume that it's in the home folder in the .cargo directory and there's a .crates2.json file that contains a list of all installed crates.

be able to dump the installed software to a format that can be stored in a Brewfile

👍🏻 Similar to the response to the last question, but I think it would probably be better to use the JSON file. So looking for that CARGO_HOME environment variable and then looking at the JSON file.

not require sudo to install (casks are an exception here)

👍🏻 Cargo installs binaries into the local user's path, usually at $CARGO_HOME/bin/, not a system path.

be extremely widely used

👍🏻 According to this search the cargo install command is in more than 83.6k repository readme files on GitHub.

[leighmcculloch]

For the purpose of reproducibility, it would be pretty important that any cargo install command was accompanied by the --locked flag to ensure that it's lock file, if present, was used.

[MikeMcQuaid]

Thanks @leighmcculloch! For my own learning: what would be the advantage over e.g. creating a formula with the cargo commands running there?

For the purpose of reproducibility, it would be pretty important that any cargo install command was accompanied by the --locked flag to ensure that it's lock file, if present, was used.

Not sure I understand this bit: where would the lock file be stored? In the upstream repository?