Azure auth fallback to real auth if refresh token fails, refactor and add more tests.

Signed-off-by: Ping He <tdihp@hotmail.com>

staging/src/k8s.io/client-go/plugin/pkg/client/auth/azure/azure.go

@@ -180,6 +180,7 @@ type azureToken struct {
 
 type tokenSource interface {
 	Token() (*azureToken, error)
+	Refresh(*azureToken) (*azureToken, error)
 }
 
 type azureTokenSource struct {
@@ -210,33 +211,66 @@ func (ts *azureTokenSource) Token() (*azureToken, error) {
 
 	var err error
 	token := ts.cache.getToken(azureTokenKey)
+
+	if token != nil && !token.token.IsExpired() {
+		return token, nil
+	}
+
+	// retrieve from config if no cache
 	if token == nil {
-		token, err = ts.retrieveTokenFromCfg()
+		tokenFromCfg, err := ts.retrieveTokenFromCfg()
-		if err != nil {
+
-			token, err = ts.source.Token()
+		if err == nil {
-			if err != nil {
+			token = tokenFromCfg
-				return nil, fmt.Errorf("acquiring a new fresh token: %v", err)
 		}
 	}
+
+	if token != nil {
+		// cache and return if the token is as good
+		// avoids frequent persistor calls
 		if !token.token.IsExpired() {
 			ts.cache.setToken(azureTokenKey, token)
-			err = ts.storeTokenInCfg(token)
+			return token, nil
+		}
+
+		klog.V(4).Info("Refreshing token.")
+		tokenFromRefresh, err := ts.Refresh(token)
+		switch {
+		case err == nil:
+			token = tokenFromRefresh
+		case autorest.IsTokenRefreshError(err):
+			klog.V(4).Infof("Failed to refresh expired token, proceed to auth: %v", err)
+			// reset token to nil so that the token source will be used to acquire new
+			token = nil
+		default:
+			return nil, fmt.Errorf("unexpected error when refreshing token: %v", err)
+		}
+	}
+
+	if token == nil {
+		tokenFromSource, err := ts.source.Token()
 		if err != nil {
-				return nil, fmt.Errorf("storing the token in configuration: %v", err)
+			return nil, fmt.Errorf("failed acquiring new token: %v", err)
 		}
+		token = tokenFromSource
 	}
+
+	// sanity check
+	if token == nil {
+		return nil, fmt.Errorf("unable to acquire token")
 	}
+
+	// corner condition, newly got token is valid but expired
 	if token.token.IsExpired() {
-		token, err = ts.refreshToken(token)
+		return nil, fmt.Errorf("newly acquired token is expired")
-		if err != nil {
-			return nil, fmt.Errorf("refreshing the expired token: %v", err)
 	}
-		ts.cache.setToken(azureTokenKey, token)
+
 	err = ts.storeTokenInCfg(token)
 	if err != nil {
 		return nil, fmt.Errorf("storing the refreshed token in configuration: %v", err)
 	}
-	}
+	ts.cache.setToken(azureTokenKey, token)
+
 	return token, nil
 }
 
@@ -314,7 +348,13 @@ func (ts *azureTokenSource) storeTokenInCfg(token *azureToken) error {
 	return nil
 }
 
-func (ts *azureTokenSource) refreshToken(token *azureToken) (*azureToken, error) {
+func (ts *azureTokenSource) Refresh(token *azureToken) (*azureToken, error) {
+	return ts.source.Refresh(token)
+}
+
+// refresh outdated token with adal.
+// adal.RefreshTokenError will be returned if error occur during refreshing.
+func (ts *azureTokenSourceDeviceCode) Refresh(token *azureToken) (*azureToken, error) {
 	env, err := azure.EnvironmentFromName(token.environment)
 	if err != nil {
 		return nil, err

staging/src/k8s.io/client-go/plugin/pkg/client/auth/azure/azure_test.go

@@ -18,6 +18,8 @@ package azure
 
 import (
 	"encoding/json"
+	"errors"
+	"net/http"
 	"strconv"
 	"strings"
 	"sync"
@@ -172,10 +174,7 @@ func TestAzureTokenSource(t *testing.T) {
 	for i, configMode := range configModes {
 		t.Run("validate token against cache", func(t *testing.T) {
 			fakeAccessToken := "fake token 1"
-			fakeSource := fakeTokenSource{
+			fakeSource := fakeTokenSource{token: newFakeAzureToken(fakeAccessToken, time.Now().Add(3600*time.Second))}
-				accessToken: fakeAccessToken,
-				expiresOn:   strconv.FormatInt(time.Now().Add(3600*time.Second).Unix(), 10),
-			}
 			cfg := make(map[string]string)
 			persiter := &fakePersister{cache: make(map[string]string)}
 			tokenCache := newAzureTokenCache()
@@ -210,7 +209,7 @@ func TestAzureTokenSource(t *testing.T) {
 				}
 			}
 
-			fakeSource.accessToken = "fake token 2"
+			fakeSource.token = newFakeAzureToken("fake token 2", time.Now().Add(3600*time.Second))
 			token, err = tokenSource.Token()
 			if err != nil {
 				t.Errorf("failed to retrieve the cached token: %v", err)
@@ -223,14 +222,161 @@ func TestAzureTokenSource(t *testing.T) {
 	}
 }
 
+func TestAzureTokenSourceScenarios(t *testing.T) {
+	configMode := configModeDefault
+	expiredToken := newFakeAzureToken("expired token", time.Now().Add(-time.Second))
+	extendedToken := newFakeAzureToken("extend token", time.Now().Add(1000*time.Second))
+	fakeToken := newFakeAzureToken("fake token", time.Now().Add(1000*time.Second))
+	wrongToken := newFakeAzureToken("wrong token", time.Now().Add(1000*time.Second))
+	tests := []struct {
+		name         string
+		sourceToken  *azureToken
+		refreshToken *azureToken
+		cachedToken  *azureToken
+		configToken  *azureToken
+		expectToken  *azureToken
+		tokenErr     error
+		refreshErr   error
+		expectErr    string
+		tokenCalls   uint
+		refreshCalls uint
+		persistCalls uint
+	}{
+		{
+			name:         "new config",
+			sourceToken:  fakeToken,
+			expectToken:  fakeToken,
+			tokenCalls:   1,
+			persistCalls: 1,
+		},
+		{
+			name:        "load token from cache",
+			sourceToken: wrongToken,
+			cachedToken: fakeToken,
+			configToken: wrongToken,
+			expectToken: fakeToken,
+		},
+		{
+			name:        "load token from config",
+			sourceToken: wrongToken,
+			configToken: fakeToken,
+			expectToken: fakeToken,
+		},
+		{
+			name:         "cached token timeout, extend success, config token should never load",
+			cachedToken:  expiredToken,
+			refreshToken: extendedToken,
+			configToken:  wrongToken,
+			expectToken:  extendedToken,
+			refreshCalls: 1,
+			persistCalls: 1,
+		},
+		{
+			name:         "config token timeout, extend failure, acquire new token",
+			configToken:  expiredToken,
+			refreshErr:   fakeTokenRefreshError{message: "FakeError happened when refreshing"},
+			sourceToken:  fakeToken,
+			expectToken:  fakeToken,
+			refreshCalls: 1,
+			tokenCalls:   1,
+			persistCalls: 1,
+		},
+		{
+			name:         "unexpected error when extend",
+			configToken:  expiredToken,
+			refreshErr:   errors.New("unexpected refresh error"),
+			sourceToken:  fakeToken,
+			expectErr:    "unexpected refresh error",
+			refreshCalls: 1,
+		},
+		{
+			name:       "token error",
+			tokenErr:   errors.New("tokenerr"),
+			expectErr:  "tokenerr",
+			tokenCalls: 1,
+		},
+		{
+			name:        "Token() got expired token",
+			sourceToken: expiredToken,
+			expectErr:   "newly acquired token is expired",
+			tokenCalls:  1,
+		},
+		{
+			name:        "Token() got nil but no error",
+			sourceToken: nil,
+			expectErr:   "unable to acquire token",
+			tokenCalls:  1,
+		},
+	}
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			persister := newFakePersister()
+
+			cfg := map[string]string{}
+			if tc.configToken != nil {
+				cfg = token2Cfg(tc.configToken)
+			}
+
+			tokenCache := newAzureTokenCache()
+			if tc.cachedToken != nil {
+				tokenCache.setToken(azureTokenKey, tc.cachedToken)
+			}
+
+			fakeSource := fakeTokenSource{
+				token:        tc.sourceToken,
+				tokenErr:     tc.tokenErr,
+				refreshToken: tc.refreshToken,
+				refreshErr:   tc.refreshErr,
+			}
+
+			tokenSource := newAzureTokenSource(&fakeSource, tokenCache, cfg, configMode, &persister)
+			token, err := tokenSource.Token()
+
+			if fakeSource.tokenCalls != tc.tokenCalls {
+				t.Errorf("expecting tokenCalls: %v, got: %v", tc.tokenCalls, fakeSource.tokenCalls)
+			}
+
+			if fakeSource.refreshCalls != tc.refreshCalls {
+				t.Errorf("expecting refreshCalls: %v, got: %v", tc.refreshCalls, fakeSource.refreshCalls)
+			}
+
+			if persister.calls != tc.persistCalls {
+				t.Errorf("expecting persister calls: %v, got: %v", tc.persistCalls, persister.calls)
+			}
+
+			if tc.expectErr != "" {
+				if !strings.Contains(err.Error(), tc.expectErr) {
+					t.Errorf("expecting error %v, got %v", tc.expectErr, err)
+				}
+				if token != nil {
+					t.Errorf("token should be nil in err situation, got %v", token)
+				}
+			} else {
+				if err != nil {
+					t.Fatalf("error should be nil, got %v", err)
+				}
+				if token.token.AccessToken != tc.expectToken.token.AccessToken {
+					t.Errorf("token should have accessToken %v, got %v", token.token.AccessToken, tc.expectToken.token.AccessToken)
+				}
+			}
+		})
+	}
+}
+
 type fakePersister struct {
 	lock  sync.Mutex
 	cache map[string]string
+	calls uint
+}
+
+func newFakePersister() fakePersister {
+	return fakePersister{cache: make(map[string]string), calls: 0}
 }
 
 func (p *fakePersister) Persist(cache map[string]string) error {
 	p.lock.Lock()
 	defer p.lock.Unlock()
+	p.calls++
 	p.cache = map[string]string{}
 	for k, v := range cache {
 		p.cache[k] = v
@@ -248,19 +394,24 @@ func (p *fakePersister) Cache() map[string]string {
 	return ret
 }
 
+// a simple token source simply always returns the token property
 type fakeTokenSource struct {
-	expiresOn   string
+	token        *azureToken
-	accessToken string
+	tokenCalls   uint
+	tokenErr     error
+	refreshToken *azureToken
+	refreshCalls uint
+	refreshErr   error
 }
 
 func (ts *fakeTokenSource) Token() (*azureToken, error) {
-	return &azureToken{
+	ts.tokenCalls++
-		token:       newFackeAzureToken(ts.accessToken, ts.expiresOn),
+	return ts.token, ts.tokenErr
-		environment: "testenv",
+}
-		clientID:    "fake",
+
-		tenantID:    "fake",
+func (ts *fakeTokenSource) Refresh(*azureToken) (*azureToken, error) {
-		apiserverID: "fake",
+	ts.refreshCalls++
-	}, nil
+	return ts.refreshToken, ts.refreshErr
 }
 
 func token2Cfg(token *azureToken) map[string]string {
@@ -276,7 +427,17 @@ func token2Cfg(token *azureToken) map[string]string {
 	return cfg
 }
 
-func newFackeAzureToken(accessToken string, expiresOn string) adal.Token {
+func newFakeAzureToken(accessToken string, expiresOnTime time.Time) *azureToken {
+	return &azureToken{
+		token:       newFakeADALToken(accessToken, strconv.FormatInt(expiresOnTime.Unix(), 10)),
+		environment: "testenv",
+		clientID:    "fake",
+		tenantID:    "fake",
+		apiserverID: "fake",
+	}
+}
+
+func newFakeADALToken(accessToken string, expiresOn string) adal.Token {
 	return adal.Token{
 		AccessToken:  accessToken,
 		RefreshToken: "fake",
@@ -287,3 +448,19 @@ func newFackeAzureToken(accessToken string, expiresOn string) adal.Token {
 		Type:         "fake",
 	}
 }
+
+// copied from go-autorest/adal
+type fakeTokenRefreshError struct {
+	message string
+	resp    *http.Response
+}
+
+// Error implements the error interface which is part of the TokenRefreshError interface.
+func (tre fakeTokenRefreshError) Error() string {
+	return tre.message
+}
+
+// Response implements the TokenRefreshError interface, it returns the raw HTTP response from the refresh operation.
+func (tre fakeTokenRefreshError) Response() *http.Response {
+	return tre.resp
+}