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Adding a token getter to get service account tokens
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package authentication | ||
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import ( | ||
"context" | ||
"sync" | ||
"time" | ||
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authenticationv1 "k8s.io/api/authentication/v1" | ||
metav1 "k8s.io/apimachinery/pkg/apis/meta/v1" | ||
"k8s.io/apimachinery/pkg/types" | ||
corev1 "k8s.io/client-go/kubernetes/typed/core/v1" | ||
"k8s.io/utils/ptr" | ||
) | ||
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type TokenGetter struct { | ||
client corev1.ServiceAccountsGetter | ||
expirationDuration time.Duration | ||
removeAfterExpiredDuration time.Duration | ||
tokens map[types.NamespacedName]*authenticationv1.TokenRequestStatus | ||
mu sync.RWMutex | ||
} | ||
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type TokenGetterOption func(*TokenGetter) | ||
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const ( | ||
RotationThresholdPercentage = 10 | ||
DefaultExpirationDuration = 5 * time.Minute | ||
DefaultRemoveAfterExpiredDuration = 90 * time.Minute | ||
) | ||
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// Returns a token getter that can fetch tokens given a service account. | ||
// The token getter also caches tokens which helps reduce the number of requests to the API Server. | ||
// In case a cached token is expiring a fresh token is created. | ||
func NewTokenGetter(client corev1.ServiceAccountsGetter, options ...TokenGetterOption) *TokenGetter { | ||
tokenGetter := &TokenGetter{ | ||
client: client, | ||
expirationDuration: DefaultExpirationDuration, | ||
removeAfterExpiredDuration: DefaultRemoveAfterExpiredDuration, | ||
tokens: map[types.NamespacedName]*authenticationv1.TokenRequestStatus{}, | ||
} | ||
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for _, opt := range options { | ||
opt(tokenGetter) | ||
} | ||
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return tokenGetter | ||
} | ||
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func WithExpirationDuration(expirationDuration time.Duration) TokenGetterOption { | ||
return func(tg *TokenGetter) { | ||
tg.expirationDuration = expirationDuration | ||
} | ||
} | ||
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func WithRemoveAfterExpiredDuration(removeAfterExpiredDuration time.Duration) TokenGetterOption { | ||
return func(tg *TokenGetter) { | ||
tg.removeAfterExpiredDuration = removeAfterExpiredDuration | ||
} | ||
} | ||
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// Get returns a token from the cache if available and not expiring, otherwise creates a new token | ||
func (t *TokenGetter) Get(ctx context.Context, key types.NamespacedName) (string, error) { | ||
t.mu.RLock() | ||
token, ok := t.tokens[key] | ||
t.mu.RUnlock() | ||
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expireTime := time.Time{} | ||
if ok { | ||
expireTime = token.ExpirationTimestamp.Time | ||
} | ||
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// Create a new token if the cached token expires within DurationPercentage of expirationDuration from now | ||
rotationThresholdAfterNow := metav1.Now().Add(t.expirationDuration * (RotationThresholdPercentage / 100)) | ||
if expireTime.Before(rotationThresholdAfterNow) { | ||
var err error | ||
token, err = t.getToken(ctx, key) | ||
if err != nil { | ||
return "", err | ||
} | ||
t.mu.Lock() | ||
t.tokens[key] = token | ||
t.mu.Unlock() | ||
} | ||
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// Delete tokens that have been expired for more than ExpiredDuration | ||
t.reapExpiredTokens(t.removeAfterExpiredDuration) | ||
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return token.Token, nil | ||
} | ||
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func (t *TokenGetter) getToken(ctx context.Context, key types.NamespacedName) (*authenticationv1.TokenRequestStatus, error) { | ||
req, err := t.client.ServiceAccounts(key.Namespace).CreateToken(ctx, | ||
key.Name, | ||
&authenticationv1.TokenRequest{ | ||
Spec: authenticationv1.TokenRequestSpec{ExpirationSeconds: ptr.To[int64](int64(t.expirationDuration))}, | ||
}, metav1.CreateOptions{}) | ||
if err != nil { | ||
return nil, err | ||
} | ||
return &req.Status, nil | ||
} | ||
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func (t *TokenGetter) reapExpiredTokens(expiredDuration time.Duration) { | ||
t.mu.Lock() | ||
defer t.mu.Unlock() | ||
for key, token := range t.tokens { | ||
if metav1.Now().Sub(token.ExpirationTimestamp.Time) > expiredDuration { | ||
delete(t.tokens, key) | ||
} | ||
} | ||
} |
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package authentication | ||
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import ( | ||
"context" | ||
"fmt" | ||
"testing" | ||
"time" | ||
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"github.com/stretchr/testify/assert" | ||
authenticationv1 "k8s.io/api/authentication/v1" | ||
metav1 "k8s.io/apimachinery/pkg/apis/meta/v1" | ||
"k8s.io/apimachinery/pkg/runtime" | ||
"k8s.io/apimachinery/pkg/types" | ||
"k8s.io/client-go/kubernetes/fake" | ||
ctest "k8s.io/client-go/testing" | ||
) | ||
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func TestTokenGetterGet(t *testing.T) { | ||
fakeClient := fake.NewSimpleClientset() | ||
fakeClient.PrependReactor("create", "serviceaccounts/token", | ||
func(action ctest.Action) (bool, runtime.Object, error) { | ||
act, ok := action.(ctest.CreateActionImpl) | ||
if !ok { | ||
return false, nil, nil | ||
} | ||
tokenRequest := act.GetObject().(*authenticationv1.TokenRequest) | ||
var err error | ||
if act.Name == "test-service-account-1" { | ||
tokenRequest.Status = authenticationv1.TokenRequestStatus{ | ||
Token: "test-token-1", | ||
ExpirationTimestamp: metav1.NewTime(metav1.Now().Add(DefaultExpirationDuration)), | ||
} | ||
} | ||
if act.Name == "test-service-account-2" { | ||
tokenRequest.Status = authenticationv1.TokenRequestStatus{ | ||
Token: "test-token-2", | ||
ExpirationTimestamp: metav1.NewTime(metav1.Now().Add(1 * time.Second)), | ||
} | ||
} | ||
if act.Name == "test-service-account-3" { | ||
tokenRequest.Status = authenticationv1.TokenRequestStatus{ | ||
Token: "test-token-3", | ||
ExpirationTimestamp: metav1.NewTime(metav1.Now().Add(-DefaultRemoveAfterExpiredDuration)), | ||
} | ||
} | ||
if act.Name == "test-service-account-4" { | ||
tokenRequest = nil | ||
err = fmt.Errorf("error when fetching token") | ||
} | ||
return true, tokenRequest, err | ||
}) | ||
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tg := NewTokenGetter(fakeClient.CoreV1(), | ||
WithExpirationDuration(DefaultExpirationDuration), | ||
WithRemoveAfterExpiredDuration(DefaultRemoveAfterExpiredDuration)) | ||
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tests := []struct { | ||
testName string | ||
serviceAccountName string | ||
namespace string | ||
want string | ||
errorMsg string | ||
}{ | ||
{"Testing getting token with fake client", "test-service-account-1", | ||
"test-namespace-1", "test-token-1", "failed to get token"}, | ||
{"Testing getting token from cache", "test-service-account-1", | ||
"test-namespace-1", "test-token-1", "failed to get token"}, | ||
{"Testing getting short lived token from fake client", "test-service-account-2", | ||
"test-namespace-2", "test-token-2", "failed to get token"}, | ||
{"Testing getting expired token from cache", "test-service-account-2", | ||
"test-namespace-2", "test-token-2", "failed to refresh token"}, | ||
{"Testing token that expired 90 minutes ago", "test-service-account-3", | ||
"test-namespace-3", "test-token-3", "failed to get token"}, | ||
{"Testing error when getting token from fake client", "test-service-account-4", | ||
"test-namespace-4", "error when fetching token", "error when fetching token"}, | ||
} | ||
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for _, tc := range tests { | ||
got, err := tg.Get(context.Background(), types.NamespacedName{Namespace: tc.namespace, Name: tc.serviceAccountName}) | ||
if err != nil { | ||
t.Logf("%s: expected: %v, got: %v", tc.testName, tc.want, err) | ||
assert.EqualError(t, err, tc.errorMsg) | ||
} else { | ||
t.Logf("%s: expected: %v, got: %v", tc.testName, tc.want, got) | ||
assert.Equal(t, tc.want, got, tc.errorMsg) | ||
} | ||
} | ||
} |