sync upstream

credentials.go

@@ -14,6 +14,7 @@ import (
 	"net"
 	"net/http"
 	"net/http/httputil"
+	"os"
 	"time"
 
 	"github.com/golang-jwt/jwt/v4"
@@ -91,9 +92,19 @@ func ServiceAccountKey(key *iamkey.Key) (Credentials, error) {
 // That is, for SDK build with InstanceServiceAccount credentials and used on Compute Instance
 // created with yandex.cloud.compute.v1.CreateInstanceRequest.service_account_id, API calls
 // will be authenticated with this ServiceAccount ID.
+// You can override the default address of Metadata Service by setting env variable.
 // TODO(skipor): doc link
 func InstanceServiceAccount() NonExchangeableCredentials {
-	return newInstanceServiceAccountCredentials(InstanceMetadataAddr)
+	return newInstanceServiceAccountCredentials(getMetadataServiceAddr())
+}
+
+// getMetadataServiceAddr returns the address of Metadata Service, gets the value from InstanceMetadataOverrideEnvVar
+// env variable if it is set, otherwise uses the default address from InstanceMetadataAddr.
+func getMetadataServiceAddr() string {
+	if nonDefaultAddr := os.Getenv(InstanceMetadataOverrideEnvVar); nonDefaultAddr != "" {
+		return nonDefaultAddr
+	}
+	return InstanceMetadataAddr
 }
 
 func newServiceAccountJWTBuilder(key *iamkey.Key) (*serviceAccountJWTBuilder, error) {

credentials_test.go

@@ -11,6 +11,7 @@ import (
 	"io"
 	"net/http"
 	"net/http/httptest"
+	"os"
 	"strings"
 	"testing"
 	"time"
@@ -117,6 +118,27 @@ func TestInstanceServiceAccount(t *testing.T) {
 	})
 }
 
+func TestMetadataServiceOverride(t *testing.T) {
+	t.Run("should return the default value", func(t *testing.T) {
+		// GIVEN
+		expected := InstanceMetadataAddr
+		// WHEN
+		actual := getMetadataServiceAddr()
+		// THEN
+		require.Equal(t, expected, actual)
+	})
+	t.Run("should be equal to value from env variable", func(t *testing.T) {
+		// GIVEN
+		expected := "69.69.69.69"
+		require.NoError(t, os.Setenv(InstanceMetadataOverrideEnvVar, expected))
+		// WHEN
+		actual := getMetadataServiceAddr()
+		// THEN
+		require.Equal(t, expected, actual)
+		require.NoError(t, os.Unsetenv(InstanceMetadataOverrideEnvVar))
+	})
+}
+
 func testKey(t *testing.T) *iamkey.Key {
 	key, err := iamkey.ReadFromJSONFile("test_data/service_account_key.json")
 	require.NoError(t, err)