Building Trow

The easiest way to build Trow is via Dockerfile. From this directory, either run build.sh or run something similar to following:

docker build -f Dockerfile -t trow ..

Note that the build context needs to be the root directory of the project (not the directory with the Dockerfile).

Mulitplatform Builds

There are several ways to produce multiplatform builds with Docker:

1. Build directly on the target hardware.
2. Use Docker multiplatform support e.g. --platform argument available with buildx to produce images for other platforms. This uses QEMU internally to emulate the target platform. In practice, I hit issues with this solution, seemingly because of bugs in QEMU and interactions with multi-stage builds.
3. Use Rust cross-compilation to produce a binary for the target platform and copy into a base image for the target platform. This requires a bit more configuration, but does work. When targeting a low-powered platform (e.g. Raspberry Pi), this option may be considerably faster than building directly on the hardware or using emulation.

Our Dockerfile uses 3 (with Docker multiplatform support to assemble the final image). Assuming you're running on amd64, you can run the following:

docker buildx build --pull --load -t trow:armv7 -f Dockerfile --platform linux/arm/v7 ../

You can build a multi-platform image (or rather manifest pointing to multiple images) with:

docker buildx build --pull --load -t trow:armv7 -f Dockerfile --platform linux/arm/v7,linux/arm64,linux/amd64 ../

But be aware that you can't load the result into a local Docker instance as it doesn't currently understand multi-platform manifests.

All of this assumes you have a recent version of Docker with buildkit installed.

Note that --pull avoids an issue whereby Docker can use the wrong base image and --load puts the image into the host Docker image cache.

If you get an error about an unsupported platform, you may need to install binfmt handlers. This can be done for common platforms with docker run --privileged --rm docker/binfmt:a7996909642ee92942dcd6cff44b9b95f08dad64 (also see qus for an alternative approach and explanation of what is happening here). Restart docker or create a new builder instance after doing this.