Please install the prerequisites first!
$ docker run --rm --runtime=io.containerd.wasmedge.v1 --platform=wasi/wasm secondstate/rust-example-hello:latest
Hello WasmEdge!
The src/main.rs source code shows
- A standalone Rust app must have a
main()function as the entry point. - In the
main()function, we create a string. The string is&strtype. In Rust, it is called a string slice meaning that this string is immutable. - We print the string using the
println!()marco. The!indicates that it is a macro, which is a set of functions to perform the task of printing to the OS console. The Rust compile expands the macro into a set of functions at compile time. There are many such macros in Rust and it is crucial that you learn them!
Compile the Rust source code project to a Wasm bytecode file.
$ cargo build --target wasm32-wasi --release
Run the Wasm bytecode file in WasmEdge CLI.
$ wasmedge target/wasm32-wasi/release/hello.wasm
Hello WasmEdge!
The Dockerfile follows the above steps to build and package a lightweight OCI-compliant container image for the Wasm app.
Now, we need to publish the container image to Docker Hub. The process is slightly different depending on how you plan to use the image.
For containerd based systems, such as the Docker Desktop and many flavors of Kubernetes,
you just need to specify that the WasmEdge application image is for the wasi/wasm platform.
$ docker buildx build --provenance=false --platform wasi/wasm -t secondstate/rust-example-hello .
... ...
$ docker push secondstate/rust-example-hello