Simplify configuration and transport

Repository creation now just takes in an http.RoundTripper. Authenticated requests or requests which require additional headers should use the NewTransport function along with a request modifier (such an an authentication handler).

Signed-off-by: Derek McGowan <derek@mcgstyle.net> (github: dmcgowan)

docs/client/transport.go

@@ -6,14 +6,36 @@ import (
 	"sync"
 )
 
-// Transport is an http.RoundTripper that makes registry HTTP requests,
-// wrapping a base RoundTripper and adding an Authorization header
-// from an Auth source
-type Transport struct {
-	AuthSource  Authorizer
-	ExtraHeader http.Header
+type RequestModifier interface {
+	ModifyRequest(*http.Request) error
+}
 
-	Base http.RoundTripper
+type headerModifier http.Header
+
+func NewHeaderRequestModifier(header http.Header) RequestModifier {
+	return headerModifier(header)
+}
+
+func (h headerModifier) ModifyRequest(req *http.Request) error {
+	for k, s := range http.Header(h) {
+		req.Header[k] = append(req.Header[k], s...)
+	}
+
+	return nil
+}
+
+func NewTransport(base http.RoundTripper, modifiers ...RequestModifier) http.RoundTripper {
+	return &transport{
+		Modifiers: modifiers,
+		Base:      base,
+	}
+}
+
+// transport is an http.RoundTripper that makes HTTP requests after
+// copying and modifying the request
+type transport struct {
+	Modifiers []RequestModifier
+	Base      http.RoundTripper
 
 	mu     sync.Mutex                      // guards modReq
 	modReq map[*http.Request]*http.Request // original -> modified
@@ -22,13 +44,14 @@ type Transport struct {
 // RoundTrip authorizes and authenticates the request with an
 // access token. If no token exists or token is expired,
 // tries to refresh/fetch a new token.
-func (t *Transport) RoundTrip(req *http.Request) (*http.Response, error) {
-	req2 := t.cloneRequest(req)
-	if t.AuthSource != nil {
-		if err := t.AuthSource.Authorize(req2); err != nil {
+func (t *transport) RoundTrip(req *http.Request) (*http.Response, error) {
+	req2 := cloneRequest(req)
+	for _, modifier := range t.Modifiers {
+		if err := modifier.ModifyRequest(req2); err != nil {
 			return nil, err
 		}
 	}
+
 	t.setModReq(req, req2)
 	res, err := t.base().RoundTrip(req2)
 	if err != nil {
@@ -43,7 +66,7 @@ func (t *Transport) RoundTrip(req *http.Request) (*http.Response, error) {
 }
 
 // CancelRequest cancels an in-flight request by closing its connection.
-func (t *Transport) CancelRequest(req *http.Request) {
+func (t *transport) CancelRequest(req *http.Request) {
 	type canceler interface {
 		CancelRequest(*http.Request)
 	}
@@ -56,14 +79,14 @@ func (t *Transport) CancelRequest(req *http.Request) {
 	}
 }
 
-func (t *Transport) base() http.RoundTripper {
+func (t *transport) base() http.RoundTripper {
 	if t.Base != nil {
 		return t.Base
 	}
 	return http.DefaultTransport
 }
 
-func (t *Transport) setModReq(orig, mod *http.Request) {
+func (t *transport) setModReq(orig, mod *http.Request) {
 	t.mu.Lock()
 	defer t.mu.Unlock()
 	if t.modReq == nil {
@@ -78,7 +101,7 @@ func (t *Transport) setModReq(orig, mod *http.Request) {
 
 // cloneRequest returns a clone of the provided *http.Request.
 // The clone is a shallow copy of the struct and its Header map.
-func (t *Transport) cloneRequest(r *http.Request) *http.Request {
+func cloneRequest(r *http.Request) *http.Request {
 	// shallow copy of the struct
 	r2 := new(http.Request)
 	*r2 = *r
@@ -87,9 +110,7 @@ func (t *Transport) cloneRequest(r *http.Request) *http.Request {
 	for k, s := range r.Header {
 		r2.Header[k] = append([]string(nil), s...)
 	}
-	for k, s := range t.ExtraHeader {
-		r2.Header[k] = append(r2.Header[k], s...)
-	}
+
 	return r2
 }