'Create a new DBInstance Read Replica.
:type id: str
:param id: Unique identifier for the new instance.
Must contain 1-63 alphanumeric characters.
First character must be a letter.
May not end with a hyphen or contain two consecutive hyphens
:type source_id: str
:param source_id: Unique identifier for the DB Instance for which this
DB Instance will act as a Read Replica.
:type instance_class: str
:param instance_class: The compute and memory capacity of the
DBInstance.  Default is to inherit from
the source DB Instance.
Valid values are:
* db.m1.small
* db.m1.large
* db.m1.xlarge
* db.m2.xlarge
* db.m2.2xlarge
* db.m2.4xlarge
:type port: int
:param port: Port number on which database accepts connections.
Default is to inherit from source DB Instance.
Valid values [1115-65535].  Defaults to 3306.
:type availability_zone: str
:param availability_zone: Name of the availability zone to place
DBInstance into.
:type auto_minor_version_upgrade: bool
:param auto_minor_version_upgrade: Indicates that minor engine
upgrades will be applied
automatically to the Read Replica
during the maintenance window.
Default is to inherit this value
from the source DB Instance.
:rtype: :class:`boto.rds.dbinstance.DBInstance`
:return: The new db instance.'

def create_dbinstance_read_replica(self, id, source_id, instance_class=None, port=3306, availability_zone=None, auto_minor_version_upgrade=None):

    params = {'DBInstanceIdentifier': id, 'SourceDBInstanceIdentifier': source_id}
    if instance_class:
        params['DBInstanceClass'] = instance_class
    if port:
        params['Port'] = port
    if availability_zone:
        params['AvailabilityZone'] = availability_zone
    if (auto_minor_version_upgrade is not None):
        if (auto_minor_version_upgrade is True):
            params['AutoMinorVersionUpgrade'] = 'true'
        else:
            params['AutoMinorVersionUpgrade'] = 'false'
    return self.get_object('CreateDBInstanceReadReplica', params, DBInstance)
