improve IAM module

Signed-off-by: hongming <talonwan@yunify.com>

vendor/k8s.io/client-go/util/cert/io.go

@@ -72,7 +72,22 @@ func WriteCert(certPath string, data []byte) error {
 // NewPool returns an x509.CertPool containing the certificates in the given PEM-encoded file.
 // Returns an error if the file could not be read, a certificate could not be parsed, or if the file does not contain any certificates
 func NewPool(filename string) (*x509.CertPool, error) {
-	certs, err := CertsFromFile(filename)
+	pemBlock, err := ioutil.ReadFile(filename)
+	if err != nil {
+		return nil, err
+	}
+
+	pool, err := NewPoolFromBytes(pemBlock)
+	if err != nil {
+		return nil, fmt.Errorf("error creating pool from %s: %s", filename, err)
+	}
+	return pool, nil
+}
+
+// NewPoolFromBytes returns an x509.CertPool containing the certificates in the given PEM-encoded bytes.
+// Returns an error if the file could not be read, a certificate could not be parsed, or if the file does not contain any certificates
+func NewPoolFromBytes(pemBlock []byte) (*x509.CertPool, error) {
+	certs, err := ParseCertsPEM(pemBlock)
 	if err != nil {
 		return nil, err
 	}