501 response...grpcwebproxy debug flag? about grpc-web HOT 5 CLOSED

Well, the typical way of debugging Go programs is... printf ;)

You can easily tweak the grpcwebproxy handling method, it's here:
https://github.com/improbable-eng/grpc-web/blob/master/go/grpcwebproxy/main.go#L77

fmt.Printf("got request: %v", req) should do the trick.

from grpc-web.

Looking at the chrome dev-tools network tab, this is the preflight request (Request Method:OPTIONS) which is actually failing with 500.

As the preflight request do not have the content-type header field, the grpcwebproxy method IsGrpcWebRequest returns false.

I believe the preflight request should not be tested with IsGrpcWebRequest method....What do you think?

from grpc-web.

this is from the grpc-nginx-gateway conf:

location / {
      grpc_pass localhost:60052;
      if ($request_method = 'OPTIONS') {
        add_header 'Access-Control-Allow-Origin' '*';
        add_header 'Access-Control-Allow-Methods' 'GET, POST, OPTIONS';
        add_header 'Access-Control-Allow-Headers' 'DNT,X-CustomHeader,Keep-Alive,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type,Content-Transfer-En$
        add_header 'Access-Control-Max-Age' 1728000;
        add_header 'Content-Type' 'text/plain charset=UTF-8';
        add_header 'Content-Length' 0;
        return 204;
      }

If request method is OPTIONS, then gateway return 204.

from grpc-web.

Oops...I just see that this behaviour is actually implemented in the wrapper.go. My bad!

from grpc-web.

I solved the preflight problem by adding:

Handler: http.HandlerFunc(func(resp http.ResponseWriter, req *http.Request) {
    resp.Header().Set("Access-Control-Allow-Origin", "*")
    resp.Header().Set("Access-Control-Allow-Methods", "GET, POST, OPTIONS")
    resp.Header().Set("Access-Control-Allow-Headers", "Origin, Content-Type")

Even if there is a function responsible to check the origin, it returns true by default, but never set the Access-Control-Allow-Origin. I'm probably doing it wrong, but it works now

from grpc-web.