wasm in golang

golang-wasm-filter-envoy.go

package main

import (
	"github.com/tetratelabs/proxy-wasm-go-sdk/proxywasm"
	"github.com/tetratelabs/proxy-wasm-go-sdk/proxywasm/types"
)
const tickMilliseconds uint32 = 15000

var authHeader string

func main() {
	proxywasm.SetVMContext(&vmContext{})
}

type vmContext struct {
	// Embed the default VM context here,
	// so that we don't need to reimplement all the methods.
	types.DefaultVMContext
}

// Override types.DefaultVMContext.
func (*vmContext) NewPluginContext(contextID uint32) types.PluginContext {
	return &pluginContext{contextID: contextID}
}

type pluginContext struct {
	// Embed the default plugin context here,
	// so that we don't need to reimplement all the methods.
	types.DefaultPluginContext
	contextID uint32
	callBack  func(numHeaders, bodySize, numTrailers int)
}

// Override types.DefaultPluginContext.
func (*pluginContext) NewHttpContext(contextID uint32) types.HttpContext {
	return &httpAuthRandom{contextID: contextID}
}

type httpAuthRandom struct {
	// Embed the default http context here,
	// so that we don't need to reimplement all the methods.
	types.DefaultHttpContext
	contextID uint32
}

// Override types.DefaultPluginContext.
func (ctx *pluginContext) OnPluginStart(pluginConfigurationSize int) types.OnPluginStartStatus {
	if err := proxywasm.SetTickPeriodMilliSeconds(tickMilliseconds); err != nil {
		proxywasm.LogCriticalf("failed to set tick period: %v", err)
		return types.OnPluginStartStatusFailed
	}
	proxywasm.LogInfof("set tick period milliseconds: %d", tickMilliseconds)
	ctx.callBack = func(numHeaders, bodySize, numTrailers int) {
		respHeaders, _ := proxywasm.GetHttpCallResponseHeaders()
		proxywasm.LogInfof("respHeaders: %v", respHeaders)

		for _, headerPairs := range respHeaders {
			if headerPairs[0] == "authorization" {
				authHeader = headerPairs[1]
			}
		}
	}
	return types.OnPluginStartStatusOK
}

func (ctx *httpAuthRandom) OnHttpResponseHeaders(int, bool) types.Action {
	proxywasm.AddHttpResponseHeader("x-wasm-filter", "hello from wasm")
	proxywasm.AddHttpResponseHeader("x-auth", authHeader)

	return types.ActionContinue
}

// Override types.DefaultPluginContext.
func (ctx *pluginContext) OnTick() {
	hs := [][2]string{
		{":method", "GET"}, {":authority", "some_authority"}, {":path", "/auth"}, {"accept", "*/*"},
	}
	if _, err := proxywasm.DispatchHttpCall("my_custom_svc", hs, nil, nil, 5000, ctx.callBack); err != nil {
		proxywasm.LogCriticalf("dispatch httpcall failed: %v", err)
	}
}