github.com/grpc-ecosystem/grpc-gateway/v2@v2.19.1/examples/internal/gateway/handlers.go (about)

     1  package gateway
     2  
     3  import (
     4  	"fmt"
     5  	"net/http"
     6  	"path"
     7  	"strings"
     8  
     9  	"google.golang.org/grpc"
    10  	"google.golang.org/grpc/connectivity"
    11  	"google.golang.org/grpc/grpclog"
    12  )
    13  
    14  // openAPIServer returns OpenAPI specification files located under "/openapiv2/"
    15  func openAPIServer(dir string) http.HandlerFunc {
    16  	return func(w http.ResponseWriter, r *http.Request) {
    17  		if !strings.HasSuffix(r.URL.Path, ".swagger.json") {
    18  			grpclog.Errorf("Not Found: %s", r.URL.Path)
    19  			http.NotFound(w, r)
    20  			return
    21  		}
    22  
    23  		grpclog.Infof("Serving %s", r.URL.Path)
    24  		p := strings.TrimPrefix(r.URL.Path, "/openapiv2/")
    25  		p = path.Join(dir, p)
    26  		http.ServeFile(w, r, p)
    27  	}
    28  }
    29  
    30  // allowCORS allows Cross Origin Resoruce Sharing from any origin.
    31  // Don't do this without consideration in production systems.
    32  func allowCORS(h http.Handler) http.Handler {
    33  	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
    34  		if origin := r.Header.Get("Origin"); origin != "" {
    35  			w.Header().Set("Access-Control-Allow-Origin", origin)
    36  			if r.Method == "OPTIONS" && r.Header.Get("Access-Control-Request-Method") != "" {
    37  				preflightHandler(w, r)
    38  				return
    39  			}
    40  		}
    41  		h.ServeHTTP(w, r)
    42  	})
    43  }
    44  
    45  // preflightHandler adds the necessary headers in order to serve
    46  // CORS from any origin using the methods "GET", "HEAD", "POST", "PUT", "DELETE"
    47  // We insist, don't do this without consideration in production systems.
    48  func preflightHandler(w http.ResponseWriter, r *http.Request) {
    49  	headers := []string{"Content-Type", "Accept", "Authorization"}
    50  	w.Header().Set("Access-Control-Allow-Headers", strings.Join(headers, ","))
    51  	methods := []string{"GET", "HEAD", "POST", "PUT", "DELETE"}
    52  	w.Header().Set("Access-Control-Allow-Methods", strings.Join(methods, ","))
    53  	grpclog.Infof("Preflight request for %s", r.URL.Path)
    54  }
    55  
    56  // healthzServer returns a simple health handler which returns ok.
    57  func healthzServer(conn *grpc.ClientConn) http.HandlerFunc {
    58  	return func(w http.ResponseWriter, r *http.Request) {
    59  		w.Header().Set("Content-Type", "text/plain")
    60  		if s := conn.GetState(); s != connectivity.Ready {
    61  			http.Error(w, fmt.Sprintf("grpc server is %s", s), http.StatusBadGateway)
    62  			return
    63  		}
    64  		fmt.Fprintln(w, "ok")
    65  	}
    66  }