Adding a user-agent to the all outgoing calls.

compute/metadata/metadata.go

@@ -28,6 +28,8 @@ import (
 	"strings"
 	"sync"
 	"time"
+
+	"google.golang.org/cloud/internal"
 )
 
 type cachedValue struct {
@@ -44,12 +46,14 @@ var (
 )
 
 var metaClient = &http.Client{
-	Transport: &http.Transport{
-		Dial: (&net.Dialer{
-			Timeout:   750 * time.Millisecond,
-			KeepAlive: 30 * time.Second,
-		}).Dial,
-		ResponseHeaderTimeout: 750 * time.Millisecond,
+	Transport: &internal.UATransport{
+		Base: &http.Transport{
+			Dial: (&net.Dialer{
+				Timeout:   750 * time.Millisecond,
+				KeepAlive: 30 * time.Second,
+			}).Dial,
+			ResponseHeaderTimeout: 750 * time.Millisecond,
+		},
 	},
 }
 

internal/cloud.go

@@ -0,0 +1,48 @@
+// Copyright 2014 Google Inc. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package internal provides support for package cloud.
+//
+// Users should not import this package directly.
+package internal
+
+import (
+	"fmt"
+	"net/http"
+)
+
+const userAgent = "gcloud-golang/0.1"
+
+// UATransport is an http.RoundTripper that appends
+// Google Cloud client's user-agent to the original
+// request's user-agent header.
+type UATransport struct {
+	// Base represents the actual http.RoundTripper
+	// the requests will be delegated to.
+	Base http.RoundTripper
+}
+
+// RoundTrip appends a user-agent to the existing user-agent
+// header and delegates the request to the base http.RoundTripper.
+func (t *UATransport) RoundTrip(req *http.Request) (*http.Response, error) {
+	// TODO(jbd): Is it OK to mutate request? UATransport is internal only.
+	ua := req.Header.Get("User-Agent")
+	if ua == "" {
+		ua = userAgent
+	} else {
+		ua = fmt.Sprintf("%s;%s", ua, userAgent)
+	}
+	req.Header.Set("User-Agent", ua)
+	return t.Base.RoundTrip(req)
+}

storage/storage.go

@@ -22,6 +22,7 @@ import (
 	"net/http"
 
 	raw "code.google.com/p/google-api-go-client/storage/v1"
+	"google.golang.org/cloud/internal"
 )
 
 const (
@@ -81,7 +82,10 @@ func New(tr http.RoundTripper) *Client {
 // uses the provided http.Client. Provided http.Client is responsible
 // to authorize and authenticate the requests made to the
 // Google Cloud Storage API.
+// It mutates the client's original Transport to append the cloud
+// package's user-agent to the outgoing requests.
 func NewWithClient(c *http.Client) *Client {
+	c.Transport = &internal.UATransport{Base: c.Transport}
 	s, _ := raw.New(c)
 	return &Client{conn: &conn{s: s, c: c}}
 }