Allow specifying a custom User-Agent when requesting original image

Related to Issue/PR #83

cmd/imageproxy/main.go

@@ -51,6 +51,7 @@ var signatureKey = flag.String("signatureKey", "", "HMAC key used in calculating
 var scaleUp = flag.Bool("scaleUp", false, "allow images to scale beyond their original dimensions")
 var timeout = flag.Duration("timeout", 0, "time limit for requests served by this proxy")
 var version = flag.Bool("version", false, "print version information")
+var userAgent = flag.String("userAgent", "willnorris/imageproxy", "specify the user-agent used by imageproxy when fetching images from origin website")
 
 func main() {
 	flag.Parse()
@@ -94,6 +95,7 @@ func main() {
 
 	p.Timeout = *timeout
 	p.ScaleUp = *scaleUp
+	p.UserAgent = *userAgent
 
 	server := &http.Server{
 		Addr:    *addr,

imageproxy.go

@@ -64,6 +64,9 @@ type Proxy struct {
 	// If a call runs for longer than its time limit, a 504 Gateway Timeout
 	// response is returned.  A Timeout of zero means no timeout.
 	Timeout time.Duration
+
+	// The User-Agent used by imageproxy when requesting origin image
+	UserAgent string
 }
 
 // NewProxy constructs a new proxy.  The provided http RoundTripper will be
@@ -130,7 +133,11 @@ func (p *Proxy) serveImage(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	resp, err := p.Client.Get(req.String())
+	actualReq, _ := http.NewRequest("GET", req.String(), nil)
+	if p.UserAgent != "" {
+		actualReq.Header.Set("User-Agent", p.UserAgent)
+	}
+	resp, err := p.Client.Do(actualReq)
 	if err != nil {
 		msg := fmt.Sprintf("error fetching remote image: %v", err)
 		glog.Error(msg)
@@ -291,9 +298,8 @@ func (t *TransformingTransport) RoundTrip(req *http.Request) (*http.Response, er
 		return t.Transport.RoundTrip(req)
 	}
 
-	u := *req.URL
-	u.Fragment = ""
-	resp, err := t.CachingClient.Get(u.String())
+	req.URL.Fragment = ""
+	resp, err := t.CachingClient.Do(req)
 	if err != nil {
 		return nil, err
 	}