Setting CORS headers using rs/cors for gqlgen

Cross-Origin Resource Sharing (CORS) headers are required when your graphql server lives on a different domain to the one your client code is served. You can read more about CORS in the MDN docs.

rs/cors

gqlgen doesn’t include a CORS implementation, but it is built to work with all standard http middleware. Here we are going to use the fantastic chi and rs/cors to build our server.

package main

import (
	"net/http"

	"github.com/99designs/gqlgen/graphql/handler/transport"
	"github.com/99designs/gqlgen/_examples/starwars"
	"github.com/99designs/gqlgen/graphql/handler"
	"github.com/go-chi/chi"
	"github.com/rs/cors"
	"github.com/gorilla/websocket"
	"github.com/99designs/gqlgen/graphql/playground"
)

func main() {
	router := chi.NewRouter()

	// Add CORS middleware around every request
	// See https://github.com/rs/cors for full option listing
	router.Use(cors.New(cors.Options{
		AllowedOrigins:   []string{"http://localhost:8080"},
		AllowCredentials: true,
		Debug:            true,
	}).Handler)


	srv := handler.New(starwars.NewExecutableSchema(starwars.NewResolver()))

	// Handle cross-origin checks in for websocket upgrade requests:
	srv.AddTransport(&transport.Websocket{
		Upgrader: websocket.Upgrader{
			CheckOrigin: func(r *http.Request) bool {
				// Check against your desired domains here
				return r.Host == "example.org"
			},
			ReadBufferSize:  1024,
			WriteBufferSize: 1024,
		},
	})
	srv.AddTransport(transport.POST{})

	router.Handle("/", playground.Handler("Starwars", "/query"))
	router.Handle("/query", srv)

	err := http.ListenAndServe(":8080", router)
	if err != nil {
		panic(err)
	}
}