struct

Data structures

Please install the prerequisites first!

Quick start with Docker

$ docker run --rm --runtime=io.containerd.wasmedge.v1 --platform=wasi/wasm secondstate/rust-example-struct:latest
English Hello WasmEdge!
Spanish Hola WasmEdge!
Texan Howdy WasmEdge!
Chinese WasmEdge 你好!

Code

The src/main.rs source code shows

• The Lang enum defines several language choices. It is annotated with the #[derive(Debug)] macro so that it can be printed later in the program.
• The Greeting struct holds both a String type message and a Lang type lang. Rust struct could also have internal functions to operate on its data fields, which makes them similar to Java objects.
• The main() program creates a Vector to hold the Greeting struct instances. The Vector::push() function is used to add elemements to the vector.
• We iterate over the vector and print out each element.

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/struct.wasm
English Hello WasmEdge!
Spanish Hola WasmEdge!
Texan Howdy WasmEdge!
Chinese WasmEdge 你好!

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. The process is slightly different depending on how you plan to use the image.

For Docker Desktop and containerd

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-struct .
... ...
$ docker push secondstate/rust-example-struct