README.md

Updates

Beginning with Rust version 1.78.0 the docker images will be based on Debian bookworm. Please report any issues you have with this update in the issue section of this repo.

Cross compiling with Docker

The native process, as described in https://github.com/Ogeon/rust-on-raspberry-pi, for cross-compiling for the Raspberry Pi sets some environment variables and writes to config files on your host machine. Thus it can be difficult to remember these changes when you want to remove or upgrade the cross compiler or even repeat that process for different versions of rust on the same machine.

To make cross-compiling Rust code for the Raspberry easier you can use the Docker image as build from the code in this repository for building your rust code but.

Basically the steps for cross compiling your project with the help of docker look like:

1. Pulling the Docker image from the dockerhub
2. Running a Docker container from that Docker image which takes your rust project (and it's platform dependencies) and then cross compiles it

You can optionally build the docker image yourself. This may be necessary if depend on stuff that is not in the image provided on the dockerhub. See section "Building your own Docker image" for a detailed instruction on how to build the image yourself.

Cross compiling your project with the image from the dockerhub

You need to pull the image first from the dockerhub (assuming you have docker installed):

docker pull ragnaroek/rust-raspberry:<version>

where <version> is the Rust compiler version. The docker images are provided starting from version 1.12.0.

If you successfully pulled the Docker image containing the cross compiler, you can cross compile your project:

$ docker run \
    --volume <path to your rust project directory>:/home/cross/project \
    --volume <path to directory containing the platform dependencies>:/home/cross/deb-deps \ # optional, see section "Platform dependencies"
    --volume <path to local cargo registry, e.g. ~/.cargo/registry>:/home/cross/.cargo/registry \ # optional, using cached registry avoids updating on every build
    ragnaroek/rust-raspberry:<version>
    <cargo command> # e.g. "build --release"

The compiled project can then be found in your target directory.

Platform dependencies (optional)

NOTE: Only Raspbian .deb files are supported currently (but we appreciate patches for other formats)

Let's say your project uses some crate that depends on having openssl installed on the system. In this case you have download the corresponding Raspbian .deb packages into a folder on your host system and then mount this directory into your docker container (See section "Cross compiling your project ...").

Get these packages either from the raspberry, or download them online.

Using apt-get to fetch packages

From a debian-based system, you may use apt-get in order to fetch packages directly from the raspbian archives. A script is provided for these purposes in the apt/ folder.

Here is how you would download libssl1.0 and all of its dependencies.

$ cd apt/
# Install the raspbian keys into your local apt keychain
$ sudo ./install-keys.sh
$ ./download.sh libssl1.0

You can also download a single deb file without recursing:

apt-get -c ./apt.conf download libssl1.0

If ran multiple times, only missing packages will be downloaded.

Adding files manually

If you do apt-cache show libssl1.0 on the raspberry, you'll see this in the output:

Filename:    pool/main/o/openssl/libssl1.0.0_1.0.1e-2+rvt+deb7u17_armhf.deb

You should be able to find a match for that under ftp.debian.org/debian/pool, so the resulting URL in this case is

http://ftp.debian.org/debian/pool/main/o/openssl/libssl-dev_1.0.1e-2+deb7u17_armhf.deb

If it's not there, see if it is still on the raspberry under /var/cache/apt/archive.

If you still can't find it, try searching for the filename online.

Additional build setup script

In order to setup the environment or do other additional processing you can define a script post-install.sh in your folder with dependencies. This script will be source-d in the shell used to do the build, so any environment variables you export will be available to the cargo process.

This script will take two arguments:

- the first argument is SYSROOT, the folder where all the cross compile headers and libraries
  are present
- the second argument is your dependency folder, you can process any non debian dependencies you
  may have pre-downloaded there

Cross compiling C dependencies

Your project may directly or indirectly depend on C libraries. The cc crate is a common approach used in the ecosystem to compile C libraries. Please see its documentation, and possibly implementation, for how to set the right environment variables.

Also note that cargo and rustc will compile code for two environments:

- the build scripts are compiled in the context of the host environment (x86\_64)
- your code is compiled for armv7 (a 32 bit environment)

When changing the environment variables you must ensure that you keep both environments working.

Building your own Docker image

$ git clone https://github.com/Ragnaroek/rust-on-raspberry-docker
$ cd rust-on-raspberry-pi/docker
$ docker build \
    --build-arg PI_TOOLS_GIT_REF=<branch/tag/commit> \ # defaults to "master"
    --build-arg RUST_VERSION=<rustup version stable/beta/nightly> \ # defaults to "stable"
    --tag <tag for your docker image> \ # e.g. "rust-nightly-pi-cross"
    .

By setting different tags for your Docker image and RUST_VERSION you could easily build images for different version of rust and use them as need.

Cross-compiling with your own build image works exactly as with the one pulled from the dockerhub. Just replace ragnaroek/rust-raspberry:<version> with your own image name.

Credits and History

The initial docker image was written by schnupperboy and maintained by Ogeon. This repository contains a copy of the docker part that originally lived in this repository: https://github.com/Ogeon/rust-on-raspberry-pi