How send request header as response header using go-kit - go

Question

I'm developing a service rest in Go using go-kit. I need send a header response. This header response should have the same value of request header.
This is a part of my transport.go:
func MakeHandler(m **http.ServeMux) http.Handler {
const URL = "..."
var serverOptions []kithttp.ServerOption
logger := log.NewLogfmtLogger(os.Stderr)
var svc repositories.SignDocumentRepository
impl := persistence.NewSignerDocumentRepository()
svc = middleware.LoggingMiddlewareSignDocument{Logger: logger, Next: impl}
registerHandler := kithttp.NewServer(
makeSignDocumentEndpoint(svc),
decodeRequest,
encodeResponse,
serverOptions...,
)
r := mux.NewRouter()
r.Handle(URL, handlers.LoggingHandler(os.Stdout, registerHandler))
(*m).Handle(URL, r)
return nil
}
func decodeRequest(_ context.Context, r *http.Request) (interface{}, error) {
return r, nil
}
func encodeResponse(_ context.Context, w http.ResponseWriter, response interface{}) error {
w.Header().Set("headerA", "val1")
w.Header().Set("headerB", "") // This header should be equal that a header request
switch response.(type) {
case model.MsgRsHdr:
w.WriteHeader(http.StatusPartialContent)
default:
w.WriteHeader(http.StatusAccepted)
}
if response != nil {
return json.NewEncoder(w).Encode(response)
}
return nil
}
How do I get a request header in encodeResponse method?

Answer 1

You can use ServerBefore to put *http.Request in the context, and can get it in encodeResponse to read request headers.
type ctxRequestKey struct{}
func putRequestInCtx(ctx context.Context, r *http.Request, _ Request) context.Context {
return context.WithValue(ctx, ctxRequestKey{}, r)
}
func encodeResponse(ctx context.Context, w http.ResponseWriter, response interface{}) error {
r := ctx.Value(ctxRequestKey{}).(*http.Request)
// can use r.Header.Get here to read request here.
}
serverOptions := []kithttp.ServerOptions{
kithttp.ServerBefore(putRequestInCtx),
}
registerHandler := kithttp.NewServer(
makeSignDocumentEndpoint(svc),
decodeRequest,
encodeResponse,
serverOptions...,
)