Using wkg to source latest WITs

[kate-goldenring]

I was walking through how to pull down the WITs to reproduce this sample from scratch and I thought i would share by steps using wkg in case it is helpful to add to CI:

1. Create a wkg config that points to the WebAssembly OCI registry for WASI packages

cat > ~/.config/wasm-pkg/config.toml <<EOL
#wkg.toml
default_registry = "ghcr.io"

[namespace_registries]
wasi = { registry = "wasi",  metadata = { preferredProtocol = "oci", "oci" = {registry = "ghcr.io", namespacePrefix = "webassembly/" } } }

[package_registry_overrides]

[registry]
EOL

2. Use wkg to get the dependency packages

mkdir -p wit/deps/http wit/deps/cli wit/deps/clocks/ wit/deps/filesystem/ wit/deps/io/ wit/deps/random/ wit/deps/sockets/
wkg get  --format wit wasi:http@0.2.3 -o wit/deps/http/
wkg get  --format wit wasi:cli@0.2.3 -o wit/deps/cli/
wkg get  --format wit wasi:clocks@0.2.3 -o wit/deps/clocks/
wkg get  --format wit wasi:filesystem@0.2.3 -o wit/deps/filesystem/
wkg get  --format wit wasi:io@0.2.3 -o wit/deps/io/
wkg get  --format wit wasi:random@0.2.3 -o wit/deps/random/
wkg get  --format wit wasi:sockets@0.2.3 -o wit/deps/sockets/

3. Add the world for the component

cat > wit/world.wit <<EOL
package sunfishcode:hello-wasi-http;

world target-world {
  include wasi:http/proxy@0.2.3;
}
EOL

[kate-goldenring]

Here is a streamlined approach using wkg fetch

mkdir -p wit
cat > wit/world.wit <<EOL
package sunfishcode:hello-wasi-http;

world target-world {
  include wasi:http/proxy@0.2.3;
}
EOL
wkg wit fetch

You have to also update the dependencies path:

# Cargo.toml
[package.metadata.component.target.dependencies]
"wasi:http" = { path = "wit/deps/wasi-http-0.2.3" }
"wasi:clocks" = { path = "wit/deps/wasi-clocks-0.2.3" }
"wasi:io" = { path = "wit/deps/wasi-io-0.2.3" }
"wasi:random" = { path = "wit/deps/wasi-random-0.2.3" }
"wasi:cli" = { path = "wit/deps/wasi-cli-0.2.3" }