Cargo packaging tools for openSUSE

This repository contains a set of tools and rpm macros intended to make it easy to package rust projects using the cargo package manager for openSUSE.

The basic concept is this: Packaging a crate should be as close as possible to a one-liner:

    cargo2rpm mkpac my-crate 1.0.0

There's some things the tool might not be able to figure out such as license, but in general this should then produce everything needed to submit a new crate to devel:languages:rust:crates.

TODO

Package and submit rustc stable, beta and nightly for Tumbleweed
Package cargo using cargo-bootstrap and update to the latest version
Look into multirust
Package the crates.io index as a separate package, plus automation to update
Implement cargo2spec

Useful tools

cargo package - Assemble package into a distributable tarball.
cargo generate-lockfile - Update Cargo.lock without actually building.
cargo metadata - Generate information about project and dependencies.

Crates and RPM packages

The idea is to package crates as very light rpm wrappers around the .crate archive. When installed, these are copied into /usr/lib/cargo/crates, and a crate registry is maintained in /usr/lib/cargo/index. When building a rust project, CARGO_HOME is set to a directory containing .cargo/config with this content:

[registry]
index = "file:///usr/lib/cargo/index"

This way, cargo will go to the local index to find crates, rather than to crates.io.

The way this is done practically is via the cargo-packaging rpm which packages this repository, which also contains a series of rpm macros. The cargo2rpm tool then edits the .spec file so that it uses these macros, which make sure to unpack the crate in the right location and update the index appropriately.

The index

The index needs to be updated when crates are installed or removed. This can be handled via pre/post hooks.

Each crate needs to install the crate itself, plus the metadata for the registry:

/usr/lib/cargo/crates/<crate-name>/<version>/download <- the crate itself
/usr/lib/cargo/crates/<crate-name>/<version>/registry.json

The data in registry.json is fetched from crates.io when the crate itself is (when creating the source rpm package).

The index data can then be inserted/removed by the registry maintenance tool

/usr/lib/cargo/index/AA/BB/

Only the index data file for the crate in question needs to be rebuilt when the crate is installed or removed.

Version handling

If multiple versions of a crate should be available, then pass --suffix "1" or --suffix "2_0" for example:

    cargo2rpm mkpac my-crate 2.0.0 --suffix 2_0

Updating a crate

To update a crate when a new version is released, just use

    cargo2rpm update my-crate

cargo index format

Description here:

https://github.com/rust-lang/cargo/blob/master/src/cargo/sources/registry.rs

In the root of the index, there is config.json:

{
  "dl": "file:///usr/lib/cargo/crates",
  "api": ""
}

In /usr/lib/cargo/index/<CR>/<AT>/<CRATE> is something like:

{"name":"xapobase-sys","vers":"0.0.1","deps":[{"name":"winapi","req":"*","features":[""],"optional":false,"default_features":true,"target":null,"kind":"normal"}],"cksum":"bfbd4e02a10678d6365ce83e31c8cce41b58bd4f4cf63b92112f80fcc499b3ed","features":{},"yanked":false}

Credits

cargo-bootstrap.py by github/@dhuseby
golang-packaging by github/@marguerite
cargo-vendor by github/@alexcrichton

krig / cargo-packaging