multiscale/scaler/grpcproxy.go
2025-06-03 16:44:30 +02:00

127 lines
3.3 KiB
Go

package main
import (
"context"
"fmt"
"log"
"net"
"github.com/mwitkow/grpc-proxy/proxy"
"google.golang.org/grpc"
"google.golang.org/grpc/credentials/insecure"
"google.golang.org/grpc/metadata"
)
var director proxy.StreamDirector
func main() {
// director = func(ctx context.Context, fullMethodName string) (context.Context, *grpc.ClientConn, error) {
// // Make sure we never forward internal services.
// if strings.HasPrefix(fullMethodName, "/com.example.internal.") {
// return nil, nil, status.Errorf(codes.Unimplemented, "Unknown method")
// }
// md, ok := metadata.FromIncomingContext(ctx)
// // Copy the inbound metadata explicitly.
// outCtx := metadata.NewOutgoingContext(ctx, md.Copy())
// if ok {
// // Decide on which backend to dial
// if val, exists := md[":authority"]; exists && val[0] == "staging.api.example.com" {
// // Make sure we use DialContext so the dialing can be cancelled/time out together with the context.
// conn, err := grpc.DialContext(ctx, "api-service.staging.svc.local")
// return outCtx, conn, err
// } else if val, exists := md[":authority"]; exists && val[0] == "api.example.com" {
// conn, err := grpc.DialContext(ctx, "api-service.prod.svc.local")
// return outCtx, conn, err
// }
// }
// return nil, nil, status.Errorf(codes.Unimplemented, "Unknown method")
// }
// director.
fmt.Println(test())
}
func test() error {
socketPath := "/state/home/projects/workbench/26-headscale-tailnets/headscale.sock"
// // Connect to Unix socket
// dst, err := grpc.Dial(
// "unix://"+socketPath,
// grpc.WithTransportCredentials(insecure.NewCredentials()),
// )
// if err != nil {
// return err
// }
// defer dst.Close()
// Connect to TCP address instead of socket
dst, err := grpc.Dial(
"localhost:8081",
grpc.WithTransportCredentials(insecure.NewCredentials()),
)
if err != nil {
return err
}
defer dst.Close()
// Create proxy with director
director := func(ctx context.Context, fullMethodName string) (context.Context, *grpc.ClientConn, error) {
log.Printf("Director called for method: %s", fullMethodName)
// Extract incoming metadata/headers
md, ok := metadata.FromIncomingContext(ctx)
if ok {
log.Printf("Forwarding headers: %v", md)
// Extract the intended host from :authority header
if authority := md.Get(":authority"); len(authority) > 0 {
log.Printf("Intended host: %s", authority[0])
}
// Also check for host header (HTTP/1.1 style)
if host := md.Get("host"); len(host) > 0 {
log.Printf("Host header: %s", host[0])
}
// Forward headers to outgoing context
ctx = metadata.NewOutgoingContext(ctx, md)
}
return ctx, dst, nil
}
// Create gRPC server with proxy handler
server := grpc.NewServer(
grpc.CustomCodec(proxy.Codec()),
grpc.UnknownServiceHandler(proxy.TransparentHandler(director)),
)
// Listen on TCP
lis, err := net.Listen("tcp", ":8090")
if err != nil {
return err
}
log.Printf("gRPC proxy listening on :8090, forwarding to %s", socketPath)
return server.Serve(lis)
}
// func test2() error {
// dst, err := grpc.Dial("example.com")
// if err != nil {
// return err
// }
// proxy := proxy.NewProxy(dst)
// grpc.Dia
// ip, err := net.ListenIP("tcp", "127.0.0.1")
// if err != nil {
// return err
// }
// proxy.Serve(ip)
// return nil
// }