Playing around with some WASI stuff
Go 1.21
hello requires any runtime that supports wasi_snapshot_preview1.
http requires a runtime that supports the WasmEdge socket extension to wasi_snapshot_preview1, e.g. WasmEdge or wasirun.
fastly requires the Viceroy or Fastly CLI locally.
export requires Go >= 1.24.0, most easily installed with gotip. It also requires wasmtime.
To build any of the demos, run make followed by the folder name:
$ make hello
GOOS=wasip1 GOARCH=wasm go build -o hello.wasm ./hello/
You can then execute the build binary in your favourite runtime:
$ wasmtime hello.wasm
Hello world
If you have wasmtime installed on your local system, you can also run the demos directly:
$ GOOS=wasip1 GOARCH=wasm PATH=$PATH:$(go env GOROOT)/misc/wasm go run ./hello
Hello world
This works by using the go_wasip1_wasm_exec script in $GOROOT/misc/wasm to execute wasmtime.
The Go toolchain automatically executes
these scripts in they are available in the path.
The runtime can be chosen using the GOWASIRUNTIME environment variable, and defaults to wasmtime.
Available options are wasmtime, wazero, wasmedge and wasmer.
The export Makefile target compiles and runs the export code, exercising the go:wasmexport compiler directive using wasmtime.
It uses -buildmode=c-shared to compile the binary as a library (AKA a reactor in wasi preview 1 terminology) with exported methods, as indicated by the presence of a _initialize export, which must be called before any exports are called.
The official blog post about WASI is a great resource: https://go.dev/blog/wasi
The proposals that led to the wasip1 implementation contain more of the nitty gritty details: https://go.dev/issue/38248, https://go.dev/issue/58141, https://go.dev/issue/59149, https://go.dev/issue/65199