HTTP <> GRPC Cortex Distributors

http-grpc-cortex-bridge-without-auth.go

package main

import (
	"fmt"
	"log"
	"net/http"

	"github.com/gorilla/mux"
	"github.com/weaveworks/common/httpgrpc"
	"github.com/weaveworks/common/httpgrpc/server"
	"google.golang.org/grpc"
)

const grpcServiceConfig = `{"loadBalancingPolicy":"round_robin"}`

type grpcProxy struct {
	client httpgrpc.HTTPClient
}

func main() {
	// if this DNS entry returns a list of IPs the above grpcServiceConfig will make grpc attempt to load balance over them
	distributorHostPort := "localhost:9001"
	listenHostPort := "192.168.1.126:8000"

	// grpc client (sends to distributor)
	dialOptions := []grpc.DialOption{
		grpc.WithDefaultServiceConfig(grpcServiceConfig),
		grpc.WithInsecure(),
	}

	conn, err := grpc.Dial(distributorHostPort, dialOptions...)
	if err != nil {
		panic(err)
	}

	proxy := &grpcProxy{
		client: httpgrpc.NewHTTPClient(conn),
	}

	// http server (receives from pushes from client)
	//  Note: the handler has been added to two common paths.  Use whatever makes sense for your config
	r := mux.NewRouter()
	r.HandleFunc("/api/v1/push", proxy.ServeHTTP)
	r.HandleFunc("/api/prom/push", proxy.ServeHTTP)
	http.Handle("/", r)

	handler := http.Handler(r)

	srv := &http.Server{
		Handler: handler,
		Addr:    listenHostPort,
	}

	fmt.Println("listening...")
	log.Fatal(srv.ListenAndServe())
}

// ServeHTTP implements http.Handler
func (g *grpcProxy) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	req, err := server.HTTPRequest(r)
	if err != nil {
		fmt.Println(err)
		return
	}

	resp, err := g.client.Handle(r.Context(), req)
	if err != nil {
		// Some errors will actually contain a valid resp, just need to unpack it
		var ok bool
		resp, ok = httpgrpc.HTTPResponseFromError(err)

		if !ok {
			fmt.Println(err)
			return
		}
	}

	if err := server.WriteResponse(w, resp); err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
}