transport/http: PopulateRequestContext

This RequestFunc moves many HTTP request parameters to the context under
specific keys. If wired in to the transport, those values are available
to subsequent endpoints or service methods that receive the context.
This can be used to e.g. log transport (HTTP) details in a service
logging middleware.

transport/http/example_test.go

@@ -0,0 +1,38 @@
+package http
+
+import (
+	"fmt"
+	"net/http"
+	"net/http/httptest"
+
+	"golang.org/x/net/context"
+)
+
+func ExamplePopulateRequestContext() {
+	handler := NewServer(
+		context.Background(),
+		func(ctx context.Context, request interface{}) (response interface{}, err error) {
+			fmt.Println("Method", ctx.Value(ContextKeyRequestMethod).(string))
+			fmt.Println("RequestPath", ctx.Value(ContextKeyRequestPath).(string))
+			fmt.Println("RequestURI", ctx.Value(ContextKeyRequestURI).(string))
+			fmt.Println("X-Request-ID", ctx.Value(ContextKeyRequestXRequestID).(string))
+			return struct{}{}, nil
+		},
+		func(context.Context, *http.Request) (interface{}, error) { return struct{}{}, nil },
+		func(context.Context, http.ResponseWriter, interface{}) error { return nil },
+		ServerBefore(PopulateRequestContext),
+	)
+
+	server := httptest.NewServer(handler)
+	defer server.Close()
+
+	req, _ := http.NewRequest("PATCH", fmt.Sprintf("%s/search?q=sympatico", server.URL), nil)
+	req.Header.Set("X-Request-Id", "a1b2c3d4e5")
+	http.DefaultClient.Do(req)
+
+	// Output:
+	// Method PATCH
+	// RequestPath /search
+	// RequestURI /search?q=sympatico
+	// X-Request-ID a1b2c3d4e5
+}

transport/http/request_response_funcs.go

@@ -22,24 +22,99 @@ type ServerResponseFunc func(context.Context, http.ResponseWriter) context.Conte
 // clients, after a request has been made, but prior to it being decoded.
 type ClientResponseFunc func(context.Context, *http.Response) context.Context
 
-// SetContentType returns a ResponseFunc that sets the Content-Type header to
-// the provided value.
+// SetContentType returns a ServerResponseFunc that sets the Content-Type header
+// to the provided value.
 func SetContentType(contentType string) ServerResponseFunc {
 	return SetResponseHeader("Content-Type", contentType)
 }
 
-// SetResponseHeader returns a ResponseFunc that sets the specified header.
+// SetResponseHeader returns a ServerResponseFunc that sets the given header.
 func SetResponseHeader(key, val string) ServerResponseFunc {
 	return func(ctx context.Context, w http.ResponseWriter) context.Context {
 		w.Header().Set(key, val)
 		return ctx
 	}
 }
 
-// SetRequestHeader returns a RequestFunc that sets the specified header.
+// SetRequestHeader returns a RequestFunc that sets the given header.
 func SetRequestHeader(key, val string) RequestFunc {
 	return func(ctx context.Context, r *http.Request) context.Context {
 		r.Header.Set(key, val)
 		return ctx
 	}
 }
+
+// PopulateRequestContext is a RequestFunc that populates several values into
+// the context from the HTTP request. Those values may be extracted using the
+// corresponding ContextKey type in this package.
+func PopulateRequestContext(ctx context.Context, r *http.Request) context.Context {
+	for k, v := range map[contextKey]string{
+		ContextKeyRequestMethod:          r.Method,
+		ContextKeyRequestURI:             r.RequestURI,
+		ContextKeyRequestPath:            r.URL.Path,
+		ContextKeyRequestProto:           r.Proto,
+		ContextKeyRequestHost:            r.Host,
+		ContextKeyRequestRemoteAddr:      r.RemoteAddr,
+		ContextKeyRequestXForwardedFor:   r.Header.Get("X-Forwarded-For"),
+		ContextKeyRequestXForwardedProto: r.Header.Get("X-Forwarded-Proto"),
+		ContextKeyRequestAuthorization:   r.Header.Get("Authorization"),
+		ContextKeyRequestReferer:         r.Header.Get("Referer"),
+		ContextKeyRequestUserAgent:       r.Header.Get("User-Agent"),
+		ContextKeyRequestXRequestID:      r.Header.Get("X-Request-Id"),
+	} {
+		ctx = context.WithValue(ctx, k, v)
+	}
+	return ctx
+}
+
+type contextKey int
+
+const (
+	// ContextKeyRequestMethod is populated in the context by
+	// PopulateRequestContext. Its value is r.Method.
+	ContextKeyRequestMethod contextKey = iota
+
+	// ContextKeyRequestURI is populated in the context by
+	// PopulateRequestContext. Its value is r.RequestURI.
+	ContextKeyRequestURI
+
+	// ContextKeyRequestPath is populated in the context by
+	// PopulateRequestContext. Its value is r.URL.Path.
+	ContextKeyRequestPath
+
+	// ContextKeyRequestProto is populated in the context by
+	// PopulateRequestContext. Its value is r.Proto.
+	ContextKeyRequestProto
+
+	// ContextKeyRequestHost is populated in the context by
+	// PopulateRequestContext. Its value is r.Host.
+	ContextKeyRequestHost
+
+	// ContextKeyRequestRemoteAddr is populated in the context by
+	// PopulateRequestContext. Its value is r.RemoteAddr.
+	ContextKeyRequestRemoteAddr
+
+	// ContextKeyRequestXForwardedFor is populated in the context by
+	// PopulateRequestContext. Its value is r.Header.Get("X-Forwarded-For").
+	ContextKeyRequestXForwardedFor
+
+	// ContextKeyRequestXForwardedProto is populated in the context by
+	// PopulateRequestContext. Its value is r.Header.Get("X-Forwarded-Proto").
+	ContextKeyRequestXForwardedProto
+
+	// ContextKeyRequestAuthorization is populated in the context by
+	// PopulateRequestContext. Its value is r.Header.Get("Authorization").
+	ContextKeyRequestAuthorization
+
+	// ContextKeyRequestReferer is populated in the context by
+	// PopulateRequestContext. Its value is r.Header.Get("Referer").
+	ContextKeyRequestReferer
+
+	// ContextKeyRequestUserAgent is populated in the context by
+	// PopulateRequestContext. Its value is r.Header.Get("User-Agent").
+	ContextKeyRequestUserAgent
+
+	// ContextKeyRequestXRequestID is populated in the context by
+	// PopulateRequestContext. Its value is r.Header.Get("X-Request-Id").
+	ContextKeyRequestXRequestID
+)