OIDC authprovider more testable, and add backoff

* Use an interface for OIDC Client, so that we're testing the behavior
  of the client, not the go-oidc package itself
* add backoff and retry when server rejects token

plugin/pkg/client/auth/oidc/oidc.go

@@ -30,6 +30,7 @@ import (
 	"github.com/golang/glog"
 
 	"k8s.io/kubernetes/pkg/client/restclient"
+	"k8s.io/kubernetes/pkg/util/wait"
 )
 
 const (
@@ -43,6 +44,15 @@ const (
 	cfgRefreshToken             = "refresh-token"
 )
 
+var (
+	backoff = wait.Backoff{
+		Duration: 1 * time.Second,
+		Factor:   2,
+		Jitter:   .1,
+		Steps:    5,
+	}
+)
+
 func init() {
 	if err := restclient.RegisterAuthProviderPlugin("oidc", newOIDCAuthProvider); err != nil {
 		glog.Fatalf("Failed to register oidc auth plugin: %v", err)
@@ -100,7 +110,7 @@ func newOIDCAuthProvider(_ string, cfg map[string]string, persister restclient.A
 			Secret: clientSecret,
 		},
 		ProviderConfig: providerCfg,
-		Scope:          scopes,
+		Scope:          append(scopes, oidc.DefaultScope...),
 	}
 
 	client, err := oidc.NewClient(oidcCfg)
@@ -108,6 +118,8 @@ func newOIDCAuthProvider(_ string, cfg map[string]string, persister restclient.A
 		return nil, fmt.Errorf("error creating OIDC Client: %v", err)
 	}
 
+	oClient := &oidcClient{client}
+
 	var initialIDToken jose.JWT
 	if cfg[cfgIDToken] != "" {
 		initialIDToken, err = jose.ParseJWT(cfg[cfgIDToken])
@@ -119,7 +131,7 @@ func newOIDCAuthProvider(_ string, cfg map[string]string, persister restclient.A
 	return &oidcAuthProvider{
 		initialIDToken: initialIDToken,
 		refresher: &idTokenRefresher{
-			client:    client,
+			client:    oClient,
 			cfg:       cfg,
 			persister: persister,
 		},
@@ -137,16 +149,57 @@ func (g *oidcAuthProvider) WrapTransport(rt http.RoundTripper) http.RoundTripper
 		RoundTripper:   rt,
 	}
 	at.SetJWT(g.initialIDToken)
-	return at
+	return &roundTripper{
+		wrapped:   at,
+		refresher: g.refresher,
+	}
 }
 
 func (g *oidcAuthProvider) Login() error {
 	return errors.New("not yet implemented")
 }
 
+type OIDCClient interface {
+	refreshToken(rt string) (oauth2.TokenResponse, error)
+	verifyJWT(jwt jose.JWT) error
+}
+
+type roundTripper struct {
+	refresher *idTokenRefresher
+	wrapped   *oidc.AuthenticatedTransport
+}
+
+func (r *roundTripper) RoundTrip(req *http.Request) (*http.Response, error) {
+	var res *http.Response
+	var err error
+	firstTime := true
+	wait.ExponentialBackoff(backoff, func() (bool, error) {
+		if !firstTime {
+			var jwt jose.JWT
+			jwt, err = r.refresher.Refresh()
+			if err != nil {
+				return true, nil
+			}
+			r.wrapped.SetJWT(jwt)
+		} else {
+			firstTime = false
+		}
+
+		res, err = r.wrapped.RoundTrip(req)
+		if err != nil {
+			return true, nil
+		}
+		if res.StatusCode == http.StatusUnauthorized {
+			return false, nil
+		}
+		return true, nil
+	})
+	return res, err
+}
+
 type idTokenRefresher struct {
 	cfg           map[string]string
-	client        *oidc.Client
+	client        OIDCClient
 	persister     restclient.AuthProviderConfigPersister
 	intialIDToken jose.JWT
 }
@@ -177,16 +230,10 @@ func (r *idTokenRefresher) Refresh() (jose.JWT, error) {
 		return jose.JWT{}, errors.New("No valid id-token, and cannot refresh without refresh-token")
 	}
 
-	oac, err := r.client.OAuthClient()
+	tokens, err := r.client.refreshToken(rt)
 	if err != nil {
-		return jose.JWT{}, err
+		return jose.JWT{}, fmt.Errorf("could not refresh token: %v", err)
 	}
-
-	tokens, err := oac.RequestToken(oauth2.GrantTypeRefreshToken, rt)
-	if err != nil {
-		return jose.JWT{}, err
-	}
-
 	jwt, err := jose.ParseJWT(tokens.IDToken)
 	if err != nil {
 		return jose.JWT{}, err
@@ -202,5 +249,22 @@ func (r *idTokenRefresher) Refresh() (jose.JWT, error) {
 		return jose.JWT{}, fmt.Errorf("could not perist new tokens: %v", err)
 	}
 
-	return jwt, r.client.VerifyJWT(jwt)
+	return jwt, r.client.verifyJWT(jwt)
+}
+
+type oidcClient struct {
+	client *oidc.Client
+}
+
+func (o *oidcClient) refreshToken(rt string) (oauth2.TokenResponse, error) {
+	oac, err := o.client.OAuthClient()
+	if err != nil {
+		return oauth2.TokenResponse{}, err
+	}
+
+	return oac.RequestToken(oauth2.GrantTypeRefreshToken, rt)
+}
+
+func (o *oidcClient) verifyJWT(jwt jose.JWT) error {
+	return o.client.VerifyJWT(jwt)
 }