fshttp: allow Transport to be customized #3631

fs/fshttp/http.go

@@ -127,9 +127,10 @@ func ResetTransport() {
 	noTransport = new(sync.Once)
 }
 
-// NewTransport returns an http.RoundTripper with the correct timeouts
-func NewTransport(ci *fs.ConfigInfo) http.RoundTripper {
-	(*noTransport).Do(func() {
+// NewTransportCustom returns an http.RoundTripper with the correct timeouts.
+// The customize function is called if set to give the caller an opportunity to
+// customize any defaults in the Transport.
+func NewTransportCustom(ci *fs.ConfigInfo, customize func(*http.Transport)) http.RoundTripper {
 	// Start with a sensible set of defaults then override.
 	// This also means we get new stuff when it gets added to go
 	t := new(http.Transport)
@@ -178,21 +179,33 @@ func NewTransport(ci *fs.ConfigInfo) http.RoundTripper {
 	}
 	t.IdleConnTimeout = 60 * time.Second
 	t.ExpectContinueTimeout = ci.ConnectTimeout
+
+	// customize the transport if required
+	if customize != nil {
+		customize(t)
+	}
+
 	// Wrap that http.Transport in our own transport
-		transport = newTransport(ci, t)
+	return newTransport(ci, t)
+}
+
+// NewTransport returns an http.RoundTripper with the correct timeouts
+func NewTransport(ci *fs.ConfigInfo) http.RoundTripper {
+	(*noTransport).Do(func() {
+		transport = NewTransportCustom(ci, nil)
 	})
 	return transport
 }
 
 // NewClient returns an http.Client with the correct timeouts
 func NewClient(ci *fs.ConfigInfo) *http.Client {
-	transport := &http.Client{
+	client := &http.Client{
 		Transport: NewTransport(ci),
 	}
 	if ci.Cookie {
-		transport.Jar = cookieJar
+		client.Jar = cookieJar
 	}
-	return transport
+	return client
 }
 
 // Transport is a our http Transport which wraps an http.Transport