class Connection(object):
    @staticmethod
    def factory(connection):
        if not connection.get('ctype'):
            try:
                evaluator = ConnectionEvaluator.factory(connection)
                connection['ctype'] = evaluator.evaluate()
            except (VpcPeeringLimitReached, CIDROverlap) as fe:
                raise ProcessConnectionUnrecoverableError(fe)

        if connection['ctype'] == 'AWS_PEERING':
            return AWSPeeringConnection(connection)
        ...
        else:
            raise NotImplementedError("Unknown connection type: {}".format(connection['ctype']))

class AWSPeeringConnection(Connection):
    def __init__(self, connection):
        super(AWSPeeringConnection, self).__init__(connection)
        ...

def create(self):
    try:
        if self._already_present():
            raise GSNVPCPeeringUnrecoverableError('VPC Peering betwen {} and {} already present'.format(
                self.left_vpc.vpc_id, self.right_vpc.vpc_id))

        response = self.left_vpc.ec2_client.create_vpc_peering_connection(
            VpcId=self.left_vpc.vpc_id,
            PeerOwnerId=self.right_vpc.account_id,
            PeerVpcId=self.right_vpc.vpc_id,
            PeerRegion=self.right_vpc.region_name,
        )
        self._peering_id = response['VpcPeeringConnection']['VpcPeeringConnectionId']
        ...

version: 3
replicas:
  minimum: 2
  maximum: 2
ingress:
  - host: ${INGRESS_DNS}
metrics:
  prometheus:
    path: /prometheus
resources:
  limits:
    memory: 1G
    cpu: 1
ports:
  - port: 8080
connectivity:
  - serviceA
  - serviceB