docker-rust-wasm

Minimal docker image for rust to wasm compilation

Based on Compiling Rust to Wasm manually with the LLVM wasm-backend (without Emscripten)

Usage

First, prepare your rust source file, e.g. add.rs.

#[no_mangle]
pub fn add_twenty_seven(n: i32) -> i32 {
  n + 27
}

Then run this docker image, compiling rust into wasm.

docker run -it --rm -v "$(pwd):/work" opengg/rust-wasm add.rs

Run an interactive shell

Alternatively, you can run an interactive shell, exploring this docker image freely.

docker run -it --rm -v "$(pwd):/work" --entrypoint bash opengg/rust-wasm

Different tags

There are three tags of this image.

tag	dependencies	example wasm build size	notes
latest (default)	rust, llvm, binaryen	0.4KB	Generating a smallest possible, zero overhead wasm file.
emscripten	rust, emscripten	88KB	Generating a wasm file and a companion js file, both come with emscripten syscall wrapping.
unknown	rust, wasm-gc	44KB	Generating a bloat wasm file, then shrink it with wasm-gc.

If you don't known what to choose, use emscripten tag:

docker run -it --rm -v "$(pwd):/work" opengg/rust-wasm:emscripten add.rs

if you want smallest possible wasm files, use latest tag.

If you want to try the newly introduced wasm32-unknown-unknown target, use unknown tag:

docker run -it --rm -v "$(pwd):/work" opengg/rust-wasm:unknown add.rs