- Caching of builds between deployments.
- Automatic updates to the latest stable Rust by default.
- Optional pinning of Rust to a specific version.
- Support for
exportso that other buildpacks can access the Rust toolchain.
- Support for compiling Rust-based extensions for projects written in other languages.
For an example project, see heroku-rust-cargo-hello.
Using this buildpack
To deploy an application to Heroku, we recommend installing the Heroku CLI.
If you're creating a new Heroku application,
cd to the directory
containing your code, and run:
heroku create --buildpack https://github.com/emk/heroku-buildpack-rust.git
This will only work if your application has a
Cargo.toml and uses
If you want to set a particular name for application, see
heroku create --help first.
To use this as the buildpack for an existing application, run:
heroku buildpacks:set https://github.com/emk/heroku-buildpack-rust.git
You will also need to create a
Procfile pointing to the release version of
your application, and commit it to
To deploy your application, run:
git push heroku master
Running Diesel migrations during the release phase
This will install the diesel CLI at build time and make it available in your dyno.
Migrations will run whenever a new version of your app is released. Add the
following line to your
and this one to your
release: ./target/release/diesel migration run
Specifying which version of Rust to use
By default, your application will be built using the latest stable Rust. Normally, this is pretty safe: New stable Rust releases have excellent backwards compatibility.
But you may wish to use
nightly Rust or to lock your Rust version to a
known-good configuration for more reproducible builds. To specify a specific
version of the toolchain, use a
rust-toolchain file in the format rustup
Note: if you previously specified a
VERSION variable in
RustConfig, that will continue to work,
and will override a
Combining with other buildpacks
If you have a project which combines both Rust and another programming language, you can insert this buildpack before your existing one as follows:
heroku buildpacks:add --index 1 https://github.com/emk/heroku-buildpack-rust.git
If you have a valid
Cargo.toml in your project, this is all you need to
do. The Rust buildpack will run first, and your existing buildpack will
But if you only need Rust to build a particular Ruby gem, and you have no
Cargo.toml file, you'll need to let the buildpack know to skip
the build stage. You can do this by adding the following line to
If you need to tweak this buildpack, the following information may help.
Testing with Docker
To test changes to the buildpack using the included
Then make sure there are no Rust-related *.so files getting linked:
This uses the Docker image
heroku/cedar, which allows us to test in an
official Cedar-like environment.
We also run this test automatically on Travis CI.