WebAssembly for Proxies (Go SDK)

The Go SDK for Proxy-Wasm, enabling developers to write Proxy-Wasm plugins in Go.

Note: This SDK targets the upstream Go compiler, version 1.24 or later. This is different than the forked github.com/tetratelabs/proxy-wasm-go-sdk, which targets the TinyGo compiler.

Project Status

This SDK is based off of github.com/tetratelabs/proxy-wasm-go-sdk; however, it is effectively a new SDK targeting a completely different toolchain. This SDK relies on the new WASI Reactors support in Go 1.24. It's been tested and used in production by customers on Google Cloud Platform's Service Extensions platform, so give it a whirl!

Getting Started

• examples directory contains the example codes on top of this SDK.
• OVERVIEW.md the overview of Proxy-Wasm, the API of this SDK, and the things you should know when writing plugins.

Requirements

• [Required] Go: v1.24+ - This SDK leverages Go 1.24's support for WASI (WebAssembly System Interface) reactors. You can install a suitable version from the Go installation guide.
• [Required] A host environment supporting this toolchain, such as Envoy >= 1.33.0. This SDK leverages additional host imports added to the proxy-wasm-cpp-host in PR#427.
• [Optional] Envoy - To run end-to-end tests, you need to have an Envoy binary. You can use func-e as an easy way to get started with Envoy or follow the official instruction.

Installation

go get github.com/proxy-wasm/proxy-wasm-go-sdk

Minimal Example Plugin

A minimal main.go plugin defining VM and Plugin contexts:

package main

import (
    "github.com/proxy-wasm/proxy-wasm-go-sdk/proxywasm"
    "github.com/proxy-wasm/proxy-wasm-go-sdk/proxywasm/types"
)

func main() {}
func init() {
    // Plugin authors can use any one of four entrypoints, such as
    // `proxywasm.SetVMContext`, `proxywasm.SetPluginContext`, or
    // `proxywasm.SetTcpContext`.
    proxywasm.SetHttpContext(func(contextID uint32) types.HttpContext {
      return &httpContext{}
    })
}
type httpContext struct {
    types.DefaultHttpContext
}
func (*httpContext) OnHttpRequestHeaders(numHeaders int, endOfStream bool) types.Action  {
    proxywasm.LogInfo("Hello, world!")
    return types.ActionContinue
}

Compile the plugin as follows:

$ go mod init main.go
$ go mod tidy
$ env GOOS=wasip1 GOARCH=wasm go build -buildmode=c-shared -o my-plugin.wasm main.go

Build and run Examples

# Build all examples.
make build.examples

# Build a specific example using the `go` tool.
cd examples/helloworld
env GOOS=wasip1 GOARCH=wasm go build -buildmode=c-shared -o main.wasm main.go

# Test the built wasm module using `go test`.
go test

# Build and test a specific example from the repo root using `make`.
make build.example name=helloworld
make run name=helloworld

Compatible Envoy builds

Envoy is the first host side implementation of Proxy-Wasm ABI, and we run end-to-end tests with multiple versions of Envoy and Envoy-based istio/proxy in order to verify Proxy-Wasm Go SDK works as expected.

Please refer to workflow.yaml for which version is used for End-to-End tests.

Build tags

The following build tags can be used to customize the behavior of the built plugin. Build tags can be specified in the go build command via the -tags flag:

• proxywasm_timing: Enables logging of time spent in invocation of the plugin's exported functions. This can be useful for debugging performance issues.

Contributing

We welcome contributions from the community! See CONTRIBUTING.md for how to contribute to this repository.

External links

• WebAssembly for Proxies (ABI specification)
• WebAssembly for Proxies (C++ SDK)
• WebAssembly for Proxies (Rust SDK)
• WebAssembly for Proxies (AssemblyScript SDK)