This topic describes how to use the Alibaba Cloud SDK for Python to create a SNAT entry.

Background information

The sample code shows the following operations:
  1. Create a virtual private cloud (VPC) in the China (Shanghai) region.
  2. Create a VSwitch for the VPC.
  3. Create a NAT gateway in the VPC.
  4. Create an elastic IP address (EIP) in the China (Shanghai) region.
  5. Associate the EIP with the NAT gateway.
  6. Create a SNAT entry.
  7. Query the EIP that is associated with the NAT gateway.
  8. Query the NAT gateway.
  9. Delete the SNAT entry.
  10. Disassociate the EIP from the NAT gateway.
  11. Delete the NAT gateway.
  12. Release the EIP.
  13. Delete the VSwitch.
  14. Delete the VPC.

Procedure

  1. In the downloaded SDK directory, open the $aliyun-openapi-python-sdk-examples\sdk_examples\examples\natgw folder.
  2. Open the natgw_snat.py file in your text editor. Set the parameters as required, save the configuration, and exit the editor.
    The following sample code is displayed:
    #encoding=utf-8
    import sys
    import json
    import time
    
    from aliyunsdkcore.acs_exception.exceptions import ServerException, ClientException
    from aliyunsdkvpc.request.v20160428 import CreateNatGatewayRequest
    from aliyunsdkvpc.request.v20160428 import DeleteNatGatewayRequest
    from aliyunsdkvpc.request.v20160428 import DescribeNatGatewaysRequest
    from aliyunsdkvpc.request.v20160428 import CreateSnatEntryRequest
    from aliyunsdkvpc.request.v20160428 import DescribeSnatTableEntriesRequest
    from aliyunsdkvpc.request.v20160428 import DeleteSnatEntryRequest
    from sdk_lib.sdk_vpc import Vpc
    from sdk_lib.sdk_vswitch import VSwitch
    from sdk_lib.sdk_eip import Eip
    from sdk_lib.sdk_cbwp import CommonBandwidthPackage
    from sdk_lib.common_util import CommonUtil
    from sdk_lib.check_status import CheckStatus
    from sdk_lib.exception import ExceptionHandler
    from sdk_lib.consts import *
    
    client = ACS_CLIENT = AcsClient(
        'accessKeyId',
        'accessSecret',
        'RegionId'
        #timeout = 35
    )
    
    
    class NatGateway(object):
        def __init__(self, client):
            self.client = client
    
        def create_nat_gateway(self, params):
            """
            create_nat_gateway: Create a NAT gateway.
            """
            try:
                request = CreateNatGatewayRequest.CreateNatGatewayRequest()
                request.set_VpcId(params['vpc_id'])
                response = client.do_action_with_exception(request)
                response_json = json.loads(response)
                # Check whether the NAT gateway is in the available state.
                if CheckStatus.check_status(TIME_DEFAULT_OUT, DEFAULT_TIME,
                                            self.describe_nat_gateway_status,
                                            AVAILABLE, response_json['NatGatewayId']):
                    return response_json
            except ServerException as e:
                ExceptionHandler.server_exception(e)
            except ClientException as e:
                ExceptionHandler.client_exception(e)
    
        def describe_nat_gateway(self, nat_gateway_id):
            """
            describe_nat_gateway: queries information about created NAT gateways in a specified region.
            """
            try:
                request = DescribeNatGatewaysRequest.DescribeNatGatewaysRequest()
                request.set_NatGatewayId(nat_gateway_id)
                response = client.do_action_with_exception(request)
                response_json = json.loads(response)
                return response_json
            except ServerException as e:
                ExceptionHandler.server_exception(e)
            except ClientException as e:
                ExceptionHandler.client_exception(e)
    
        def delete_nat_gateway(self, params):
            """
            delete_nat_gateway: deletes the NAT gateway.
            """
            try:
                request = DeleteNatGatewayRequest.DeleteNatGatewayRequest()
                request.set_NatGatewayId(params['nat_gateway_id'])
                response = client.do_action_with_exception(request)
                response_json = json.loads(response)
                # Check whether the NAT gateway is in the available state.
                if CheckStatus.check_status(TIME_DEFAULT_OUT, DEFAULT_TIME * 5,
                                            self.describe_nat_gateway_status,
                                            '', params['nat_gateway_id']):
                    return response_json
            except ServerException as e:
                ExceptionHandler.server_exception(e)
            except ClientException as e:
                ExceptionHandler.client_exception(e)
    
        def describe_nat_gateway_status(self, nat_gateway_id):
            """
            describe_nat_gateway_status: queries the status of created NAT gateways in a specified region.
            """
            response = self.describe_nat_gateway(nat_gateway_id)
            if len(response["NatGateways"]["NatGateway"]) == 0:
                return ''
            return response["NatGateways"]["NatGateway"][0]['Status']
    
        def create_snat_entry(self, params):
            """
            describe_snat: creates a SNAT entry.
            """
            try:
                request = CreateSnatEntryRequest.CreateSnatEntryRequest()
                request.set_SnatTableId(params['snat_table_id'])
                request.set_SourceVSwitchId(params['vswitch_id'])
                request.set_SnatIp(params['snat_ip'])
                response = client.do_action_with_exception(request)
                response_json = json.loads(response)
                # Check whether the SNAT Entry is in the available state.
                if CheckStatus.check_status(TIME_DEFAULT_OUT, DEFAULT_TIME,
                                            self.describe_snat_status,
                                            AVAILABLE, params['snat_table_id']):
                    return response_json
            except ServerException as e:
                ExceptionHandler.server_exception(e)
            except ClientException as e:
                ExceptionHandler.client_exception(e)
    
        def describe_snat(self, snat_table_id):
            """
            describe_snat: queries the created SNAT entries of a specified region.
            """
            try:
                request = DescribeSnatTableEntriesRequest.DescribeSnatTableEntriesRequest()
                request.set_SnatTableId(snat_table_id)
                response = client.do_action_with_exception(request)
                response_json = json.loads(response)
                return response_json
            except ServerException as e:
                ExceptionHandler.server_exception(e)
            except ClientException as e:
                ExceptionHandler.client_exception(e)
    
        def describe_snat_status(self, snat_table_id):
            """
            describe_snat_status: queries the status of created SNAT entries in a specified region.
            """
            response = self.describe_snat(snat_table_id)
            if len(response["SnatTableEntries"]["SnatTableEntry"]) == 0:
                return ''
            return response["SnatTableEntries"]["SnatTableEntry"][0]['Status']
    
        def delete_snat_entry(self, params):
            """
            delete_snat_entry: deletes the SNAT entry.
            """
            try:
                request = DeleteSnatEntryRequest.DeleteSnatEntryRequest()
                request.set_SnatTableId(params['snat_table_id'])
                request.set_SnatEntryId(params['snat_entry_id'])
                response = client.do_action_with_exception(request)
                response_json = json.loads(response)
                # Check whether the SNAT entry is in the available state.
                if CheckStatus.check_status(TIME_DEFAULT_OUT, DEFAULT_TIME * 5,
                                            self.describe_snat_status,
                                            '', params['snat_table_id']):
                    return response_json
            except ServerException as e:
                ExceptionHandler.server_exception(e)
            except ClientException as e:
                ExceptionHandler.client_exception(e)
    
    
    def main():
        vpc = Vpc(client)
        vswitch = VSwitch(client)
        eip = Eip(client)
        cbwp = CommonBandwidthPackage(client)
        nat_gateway = NatGateway(client)
    
        params = {}
    
        # Create a VPC.
        vpc_json = vpc.create_vpc()
        CommonUtil.log("create_vpc", vpc_json)
    
        # Create a VSwitch.
        params['vpc_id'] = vpc_json['VpcId']
        params['zone_id'] = "cn-hangzhou-d"
        params['cidr_block'] = "172.16.1.0/24"
        vswitch_json = vswitch.create_vswitch(params)
        CommonUtil.log("create_vswitch", vswitch_json)
        params['vswitch_id'] = vswitch_json['VSwitchId']
    
        # Create a NAT gateway.
        nat_gateway_json = nat_gateway.create_nat_gateway(params)
        CommonUtil.log("create_nat_gateway", nat_gateway_json)
    
        # Create an EIP.
        eip_response_json = eip.allocate_eip_address(params)
        CommonUtil.log("allocate_eip_address", eip_response_json)
        params['allocation_id'] = eip_response_json["AllocationId"]
        params['snat_ip'] = eip_response_json['EipAddress']
    
        # Associate the EIP with the NAT gateway.
        params['instance_id'] = nat_gateway_json['NatGatewayId']
        params['allocation_id'] = eip_response_json["AllocationId"]
        params['instance_type'] = 'Nat'
        eip_response_json = eip.associate_eip_address(params)
        CommonUtil.log("associate_eip_address eip", eip_response_json)
    
        # Create a SNAT entry.
        params['snat_table_id'] = nat_gateway_json['SnatTableIds']['SnatTableId'][0]
        snat_entry_json = nat_gateway.create_snat_entry(params)
        CommonUtil.log("create_snat_entry", snat_entry_json)
    
        # Query EIPs.
        eip_response_json = eip.describe_eip_address(params['allocation_id'])
        CommonUtil.log("describe_eip_address", eip_response_json)
    
        # Query NAT gateways.
        params['nat_gateway_id'] = nat_gateway_json['NatGatewayId']
        nat_gateway_json = nat_gateway.describe_nat_gateway(params['nat_gateway_id'])
        CommonUtil.log("describe_nat_gateway", nat_gateway_json)
    
        # Delete the SNAT entry.
        params['snat_entry_id'] = snat_entry_json['SnatEntryId']
        snat_entry_json = nat_gateway.delete_snat_entry(params)
        CommonUtil.log("delete_snat_entry", snat_entry_json)
    
        # Disassociate the EIP from the NAT gateway.
        eip_response_json = eip.unassociate_eip_address(params)
        CommonUtil.log("unassociate_eip_address nat", eip_response_json)
    
        # Delete the NAT gateway.
        nat_gateway_json = nat_gateway.delete_nat_gateway(params)
        CommonUtil.log("delete_nat_gateway", nat_gateway_json)
    
        # Release the EIP.
        eip_response_json = eip.release_eip_address(params)
        CommonUtil.log("release_eip_address", eip_response_json)
    
        # Delete the VSwitch.
        params['vswitch_id'] = vswitch_json['VSwitchId']
        vswitch_json = vswitch.delete_vswitch(params)
        CommonUtil.log("delete_vswitch", vswitch_json)
    
        # Delete the VPC.
        vpc_json = vpc.delete_vpc(params)
        CommonUtil.log("delete_vpc", vpc_json)
    
    
    if __name__ == "__main__":
        sys.exit(main())
  3. Go to the natgw_snat.py directory and run the following command to create a SNAT entry:
    python natgw_snat.py

Result

The following output is returned:
---------------------------create_vpc---------------------------
{
  "ResourceGroupId": "rg-acfmxazxxxxxxxx",
  "RouteTableId": "vtb-uf6a8ccj9ne58xxxxxxxx",
  "VRouterId": "vrt-uf6qqqaf1o1ptxxxxxxxx",
  "VpcId": "vpc-uf6hxer3h07wgxxxxxxxx",
  "RequestId": "8F483A7B-8A38-47ED-85BD-1E83C075AEA4"
}

---------------------------create_vswitch---------------------------
{
  "VSwitchId": "vsw-uf6lbov9tyetqxxxxxxxx",
  "RequestId": "2EE2E11B-EF60-4C88-BE2A-F45517290B31"
}

---------------------------create_nat_gateway---------------------------
{
  "NatGatewayId": "ngw-uf6l3c3rswubuxxxxxxxx",
  "BandwidthPackageIds": {
    "BandwidthPackageId": []
  },
  "ForwardTableIds": {
    "ForwardTableId": [
      "ftb-uf6086r1hyecbxxxxxxxx"
    ]
  },
  "RequestId": "9037D769-24C8-46AD-83F3-4C0538FA5970",
  "SnatTableIds": {
    "SnatTableId": [
      "stb-uf6ppo11rsecmxxxxxxxx"
    ]
  }
}

---------------------------allocate_eip_address---------------------------
{
  "EipAddress": "101.xx.xx.110",
  "ResourceGroupId": "rg-acfmxazxxxxxxxx",
  "RequestId": "0DE621B4-6BDE-4E17-A294-8F71FBB9F710",
  "AllocationId": "eip-uf6d311cpmr0nxxxxxxxx"
}

---------------------------associate_eip_address eip---------------------------
{
  "RequestId": "C95B2EDC-F081-4784-B60B-2600F60E684D"
}

---------------------------create_snat_entry---------------------------
{
  "SnatEntryId": "snat-uf6ppbwshdu40xxxxxxxx",
  "RequestId": "BB9F8FD2-3CB5-4F84-8006-FE64BF3BEA06"
}

---------------------------describe_eip_address---------------------------
{
  "TotalCount": 1,
  "PageNumber": 1,
  "PageSize": 10,
  "EipAddresses": {
    "EipAddress": [
      {
        "ISP": "BGP",
        "ExpiredTime": "",
        "InternetChargeType": "PayByBandwidth",
        "IpAddress": "101.xx.xx.110",
        "AllocationId": "eip-uf6d311cpmr0nxxxxxxxx",
        "PrivateIpAddress": "",
        "Status": "InUse",
        "BandwidthPackageId": "",
        "InstanceId": "ngw-uf6l3c3rswubuxxxxxxxx",
        "InstanceRegionId": "cn-shanghai",
        "RegionId": "cn-shanghai",
        "AvailableRegions": {
          "AvailableRegion": [
            "cn-shanghai"
          ]
        },
        "ResourceGroupId": "rg-acfmxazxxxxxxxx",
        "HasReservationData": false,
        "InstanceType": "Nat",
        "AllocationTime": "2019-04-24T11:20:09Z",
        "Name": "",
        "OperationLocks": {
          "LockReason": []
        },
        "Mode": "NAT",
        "BandwidthPackageType": "",
        "BandwidthPackageBandwidth": "",
        "Bandwidth": "5",
        "HDMonitorStatus": "OFF",
        "ChargeType": "PostPaid",
        "SecondLimited": false,
        "Descritpion": ""
      }
    ]
  },
  "RequestId": "19052237-6E84-4258-89B9-05772C33C0DC"
}

---------------------------describe_nat_gateway---------------------------
{
  "TotalCount": 1,
  "PageNumber": 1,
  "RequestId": "26CAA3FE-B400-4522-9582-2DAAF69129AE",
  "PageSize": 10,
  "NatGateways": {
    "NatGateway": [
      {
        "Status": "Available",
        "BandwidthPackageIds": {
          "BandwidthPackageId": []
        },
        "VpcId": "vpc-uf6hxer3h07wgxxxxxxxx",
        "Description": "",
        "ForwardTableIds": {
          "ForwardTableId": [
            "ftb-uf6086r1hyecbxxxxxxxx"
          ]
        },
        "IpLists": {
          "IpList": [
            {
              "UsingStatus": "UsedBySnatTable",
              "IpAddress": "101.xx.xx.110",
              "AllocationId": "eip-uf6d311cpmr0nxxxxxxxx"
            }
          ]
        },
        "BusinessStatus": "Normal",
        "RegionId": "cn-shanghai",
        "CreationTime": "2019-04-24T11:20:06Z",
        "NatGatewayId": "ngw-uf6l3c3rswubuxxxxxxxx",
        "SnatTableIds": {
          "SnatTableId": [
            "stb-uf6ppo11rsecmxxxxxxxx"
          ]
        },
        "AutoPay": false,
        "InstanceChargeType": "PostPaid",
        "ExpiredTime": "",
        "Spec": "Small",
        "Name": ""
      }
    ]
  }
}

---------------------------delete_snat_entry---------------------------
{
  "RequestId": "CDA82881-ACF0-4DD1-887B-A764F56F180D"
}

---------------------------unassociate_eip_address nat--------------------------
-
{
  "RequestId": "140C46FF-0DB0-47F9-B0F4-3459DF117EAF"
}

---------------------------delete_nat_gateway---------------------------
{
  "RequestId": "8709747C-6786-443C-8AEA-51647AA49769"
}

---------------------------release_eip_address---------------------------
{
  "RequestId": "0BC21C23-0FB3-4594-8B14-6552DF788C93"
}

---------------------------delete_vswitch---------------------------
{
  "RequestId": "16E840EC-E058-40C1-A5BF-8CDF672EA139"
}

---------------------------delete_vpc---------------------------
{
  "RequestId": "B5F18126-FF2A-4005-9973-3984034DF0F4"
}