muslrust

A plain docker environment for building static binaries compiled with rust and linked against musl instead of glibc.

This is only useful if you require external C dependencies, because otherwise you could do rustup target add x86_64-unknown-linux-musl.

This container comes with openssl and curl compiled against musl-gcc so that we can statically link against these system libraries as well.

Usage

Pull and run from a rust project root:

docker pull clux/muslrust
docker run -v $PWD:/volume -w /volume -t clux/muslrust cargo build

You should have a static executable in the target folder:

ldd target/x86_64-unknown-linux-musl/debug/EXECUTABLE
        not a dynamic executable

From there on, you can include it in a blank docker image (because everything you need is included in the binary) and perhaps end up with a 5MB docker blog image.

Docker builds

Latest is always the last built nightly pushed by travis. To pin against specific builds, see the available tags on the docker hub.

C Libraries

The following system libraries are compiled against musl-gcc:

curl (curl crate)
openssl (openssl crate)

We try to keep these up to date.

zlib is not included as the common flate2 crate bundles miniz.c as the default implementation, and this just works.

Developing

Clone, tweak, build, and run tests:

git clone git@github.com:clux/muslrust.git && cd muslrust
make build
make test

The tests verify that you can use hyper, curl, openssl, flate2, and rand in simplistic ways.

SSL Verification

You need to point openssl at the location of your certificates explicitly to have https requests not return certificate errors.

export SSL_CERT_FILE=/etc/ssl/certs/ca-certificates.crt
export SSL_CERT_DIR=/etc/ssl/certs

You can also hardcode this in your binary, or, more sensibly set it in your running docker image.

Caching Cargo Locally

Repeat builds locally are always from scratch (thus slow) without a cached cargo directory. You can set up a docker volume by just adding -v cargo-cache:/root/.cargo to the docker run command.

You'll have an extra volume that you can inspect with docker volume inspect cargo-cache.

Suggested developer usage is to add the following function to your ~/.bashrc:

musl-build() {
  docker run \
    -v cargo-cache:/root/.cargo \
    -v "$PWD:/volume" -w /volume \
    --rm -it clux/muslrust cargo build --release
}

Then use in your project:

$ cd myproject
$ musl-build
    Finished release [optimized] target(s) in 0.0 secs

Second time around this will be quick, and you can even mix it with native cargo build calls without screwing with your cache.

opensourcegeek / muslrust