hello

Hello WasmEdge

Please install the prerequisites first!

Quick start with Docker

$ docker run --rm --runtime=io.containerd.wasmedge.v1 --platform=wasi/wasm secondstate/rust-example-hello:latest
Hello WasmEdge!

Code

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 &str type. 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!

Step by step guide

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!

Build and publish on Docker

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. You just need to specify that the WasmEdge application image is for the wasi/wasm platform.

$ docker buildx build --platform wasi/wasm -t secondstate/rust-example-hello .
... ...
$ docker push secondstate/rust-example-hello