Function GetMasterKeyFromSlaveStatus

go/mysql/utils.go:88–130

(dbVersion string, connectionConfig *ConnectionConfig)

}

func GetMasterKeyFromSlaveStatus(dbVersion string, connectionConfig *ConnectionConfig) (masterKey *InstanceKey, err error) {
	currentUri := connectionConfig.GetDBUri("information_schema")
	// This function is only called once, okay to not have a cached connection pool
	db, err := gosql.Open("mysql", currentUri)
	if err != nil {
		return nil, err
	}
	defer db.Close()

	showReplicaStatusQuery := fmt.Sprintf("show %s", ReplicaTermFor(dbVersion, `slave status`))
	err = sqlutils.QueryRowsMap(db, showReplicaStatusQuery, func(rowMap sqlutils.RowMap) error {
		// We wish to recognize the case where the topology's master actually has replication configuration.
		// This can happen when a DBA issues a `RESET SLAVE` instead of `RESET SLAVE ALL`.

		// An empty log file indicates this is a master:
		if rowMap.GetString(ReplicaTermFor(dbVersion, "Master_Log_File")) == "" {
			return nil
		}

		ioRunningTerm := ReplicaTermFor(dbVersion, "Slave_IO_Running")
		sqlRunningTerm := ReplicaTermFor(dbVersion, "Slave_SQL_Running")
		slaveIORunning := rowMap.GetString(ioRunningTerm)
		slaveSQLRunning := rowMap.GetString(sqlRunningTerm)

		if slaveIORunning != "Yes" || slaveSQLRunning != "Yes" {
			return fmt.Errorf("replication on %+v is broken: %s: %s, %s: %s. Please make sure replication runs before using gh-ost",
				connectionConfig.Key,
				ioRunningTerm,
				slaveIORunning,
				sqlRunningTerm,
				slaveSQLRunning,
			)
		}

		masterKey = &InstanceKey{
			Hostname: rowMap.GetString(ReplicaTermFor(dbVersion, "Master_Host")),
			Port:     rowMap.GetInt(ReplicaTermFor(dbVersion, "Master_Port")),
		}
		return nil
	})

	return masterKey, err
}

func GetMasterConnectionConfigSafe(dbVersion string, connectionConfig *ConnectionConfig, visitedKeys *InstanceKeyMap, allowMasterMaster bool) (masterConfig *ConnectionConfig, err error) {
	log.Debugf("Looking for %s on %+v", ReplicaTermFor(dbVersion, "master"), connectionConfig.Key)