wasmCloud Go

Go SDK, examples, and project templates for building WebAssembly components that run on wasmCloud v2.

• component (go.wasmcloud.dev/component) — the component SDK: write HTTP handlers with standard net/http types and compile them to WASI components with big Go via componentize-go. Two worlds are supported: a sync WASI P2 world (default, stock Go) and an async WASI P3 world (wasi:http@0.3.0, streaming bodies and native goroutine concurrency).
• component/nats — NATS-native messaging on wasmcloud:nats@0.1.0: core pub/sub and request-reply, JetStream, and JetStream KV, for what the portable component/messaging package cannot express — acknowledged delivery and redelivery, replay from an arbitrary stream position, and compare-and-swap on a KV revision. Every function on the interface is async, so a component importing it targets WASI P3.
• examples/components — runnable example components, each a standalone Go module.
• templates — starter templates for wash new.
• x — experimental libraries.

Quickstart

wash new https://github.com/wasmCloud/go.git --name my-component \
  --subfolder templates/http-hello-world
cd my-component
wash dev

Examples

Example	Shows	WASI P3
http-server	HTTP routing and handlers via net/http
http-client	Outbound HTTP with http.RoundTripper
http-password-checker	A small JSON API
http-keyvalue-crud	HTTP CRUD over host-served wasi:keyvalue
http-otel	OpenTelemetry tracing via the host's wasi:otel plugin
http-p3-streaming	Async WASI P3: streaming echo + concurrent outbound fan-out	✅
nats-request-reply	Core NATS request-reply: a responder plus an HTTP gateway that calls it	✅
nats-jetstream-orders	JetStream delivery into KV, with ack/nak and compare-and-swap	✅
nats-kv-watch	Watching a JetStream KV bucket and rebuilding derived state	✅
nats-stream-replay	JetStream replay by sequence or range, and a pull consumer you settle yourself	✅

The unmarked examples build as sync WASI P2 components with stock Go. The marked ones target the async P3 world: http-p3-streaming asks for it directly, and the nats-* examples inherit it because every function on wasmcloud:nats@0.1.0 is async. componentize-go selects a patched Go toolchain for those automatically — see http-p3-streaming.

Migrating from wasmCloud v1

wasmCloud v2 removed wadm manifests, capability providers, and the wasmcloud:bus interface; the v1-era provider SDK (go.wasmcloud.dev/provider) and TinyGo component SDK line (v0.0.x) are no longer developed on main, though existing module versions keep resolving. See MIGRATING.md.