Introducing rust-musl-cross-docker-arch

I created a project called rust-musl-cross-docker-arch.

This is simply a retagged version of rust-musl-cross with tags in the format ${RUST_VERSION}-${ARCH} (e.g., 1.83.0-arm64).

What is rust-musl-cross?

This is a Docker image that allows you to cross-compile static Rust programs for various architectures using musl. It is very convenient when you need to cross-build.

Even without cross-building, creating statically compiled applications lets you transfer only the Rust binary to a small base image, enabling you to create compact Docker images, which can improve deployment speed. Personally, I use this image to create small Docker images when deploying to low-spec edge devices or VPS environments.

For example, the Dockerfile for this blog (operated on a budget VPS) looks like this:

ARG RUST_VERSION=latest

FROM ghcr.io/typester/rust-musl-cross-docker-arch:$RUST_VERSION-$TARGETARCH AS builder

COPY . .
RUN cargo build --release --target ${RUST_MUSL_CROSS_TARGET}

# Runtime
FROM alpine

WORKDIR /app

# Timezone PST
RUN apk add --no-cache tzdata
ENV TZ=America/Los_Angeles

# Copy application binary from builder image
COPY --from=builder /home/rust/src/target/*/release/blog .
# Copy static files
COPY ./public /app/public

ENV RUST_LOG=info

EXPOSE 3000

CMD ["/app/blog"]

This results in an image of 16.8MB. If you strip the binary (not shown here), the size can be reduced to around 15MB.

Using even smaller base images like scratch can make the image smaller, but such images make it harder to debug issues within the container if something goes wrong. That’s why I use alpine.

This project was created to address the difficulty of writing Dockerfiles when using the rust-musl-cross tags, especially when supporting multi-architecture builds, by retagging images to better suit my needs.

I created this for personal use, but anyone else who wants to use it is more than welcome. Feedback is also greatly appreciated!

There is also muslrust

While writing this article, I found another project called muslrust. This project also provides base images for creating small Docker images. It includes libraries like OpenSSL and libcurl, which are commonly used, making it a good choice for those who need them.