added credentials provider for basic auth

plumbing/transport/http/common.go

@@ -66,6 +66,9 @@ func (s *session) applyAuthToRequest(req *http.Request) {
 	s.auth.setAuth(req)
 }
 
+// CredentialsProvider is a function that returns a username and password
+type CredentialsProvider func() (string, string)
+
 // AuthMethod is concrete implementation of common.AuthMethod for HTTP services
 type AuthMethod interface {
 	transport.AuthMethod
@@ -89,19 +92,34 @@ func basicAuthFromEndpoint(ep transport.Endpoint) *BasicAuth {
 
 // BasicAuth represent a HTTP basic auth
 type BasicAuth struct {
-	username, password string
+	CredentialsProvider CredentialsProvider
+	username, password  string
 }
 
 // NewBasicAuth returns a basicAuth base on the given user and password
 func NewBasicAuth(username, password string) *BasicAuth {
-	return &BasicAuth{username, password}
+	ba := &BasicAuth{
+		username: username,
+		password: password,
+	}
+
+	ba.CredentialsProvider = ba.defaultCredentialsProvider
+	return ba
+}
+
+func (a *BasicAuth) defaultCredentialsProvider() (string, string) {
+	return a.username, a.password
 }
 
 func (a *BasicAuth) setAuth(r *http.Request) {
 	if a == nil {
 		return
 	}
 
+	if len(a.username) < 1 || len(a.password) < 1 {
+		a.username, a.password = a.CredentialsProvider()
+	}
+
 	r.SetBasicAuth(a.username, a.password)
 }
 

plumbing/transport/http/common_test.go

@@ -86,6 +86,18 @@ func (s *ClientSuite) TestSetAuth(c *C) {
 	c.Assert(auth, Equals, r.(*upSession).auth)
 }
 
+func (s *ClientSuite) TestCredentialsProvider(c *C) {
+	auth := &BasicAuth{}
+	auth.CredentialsProvider = func() (string, string) { return "foo", "b4r" }
+	req, _ := http.NewRequest("GET", "foo", nil)
+	auth.setAuth(req)
+	u, p, ok := req.BasicAuth()
+
+	c.Assert(u, Equals, "foo")
+	c.Assert(p, Equals, "b4r")
+	c.Assert(ok, Equals, true)
+}
+
 type mockAuth struct{}
 
 func (*mockAuth) Name() string   { return "" }