tabletserver: Skip wait for DBA grants for external tablets (#14629)

Signed-off-by: Dirkjan Bussink <[email protected]>

go/vt/vttablet/tabletserver/tabletserver.go

@@ -234,7 +234,9 @@ func NewTabletServer(ctx context.Context, name string, config *tabletenv.TabletC
 
 // WaitForDBAGrants waits for DBA user to have the required privileges to function properly.
 func WaitForDBAGrants(config *tabletenv.TabletConfig, waitTime time.Duration) error {
-	if waitTime == 0 {
+	// We don't wait for grants if the tablet is externally managed. Permissions
+	// are then the responsibility of the DBA.
+	if config.DB.HasGlobalSettings() || waitTime == 0 {
 		return nil
 	}
 	timer := time.NewTimer(waitTime)

go/vt/vttablet/tabletserver/tabletserver_test.go

@@ -2706,12 +2706,38 @@ func TestWaitForDBAGrants(t *testing.T) {
 					cluster.TearDown()
 				}
 			},
+		}, {
+			name:      "Success for externally managed tablet",
+			waitTime:  300 * time.Millisecond,
+			errWanted: "",
+			setupFunc: func(t *testing.T) (*tabletenv.TabletConfig, func()) {
+				// Create a new mysql but don't give the grants to the vt_dba user at all.
+				// This should cause a timeout after waiting, since the privileges are never granted.
+				testUser := "vt_test_dba"
+				cluster, err := startMySQLAndCreateUser(t, testUser)
+				require.NoError(t, err)
+
+				tc := &tabletenv.TabletConfig{
+					DB: &dbconfigs.DBConfigs{
+						Host: "some.unknown.host",
+					},
+				}
+				connParams := cluster.MySQLConnParams()
+				connParams.Uname = testUser
+				tc.DB.SetDbParams(connParams, mysql.ConnParams{}, mysql.ConnParams{})
+				return tc, func() {
+					cluster.TearDown()
+				}
+			},
 		}, {
 			name:      "Empty timeout",
 			waitTime:  0,
 			errWanted: "",
 			setupFunc: func(t *testing.T) (*tabletenv.TabletConfig, func()) {
-				return nil, func() {}
+				tc := &tabletenv.TabletConfig{
+					DB: &dbconfigs.DBConfigs{},
+				}
+				return tc, func() {}
 			},
 		},
 	}