string

Strings

Please install the prerequisites first!

Quick start with Docker

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

Code

The src/main.rs source code shows

• The Rust string can hold special characters and line breaks. The art variable is a complex string literal. It prints an ASCII art on the console.
• The hello variable is an immutable &str type. So, when you operate on it, the operation / function returns a String type.
• The String type variable howdy can now be manipulated and changed. It is very much like a StringBuffer in the Java world.

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/string.wasm
... ART ...
Hello WasmEdge!
Howdy WasmEdge!
Howdy WasmEdge! -- from Texas

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