How to get the port mapping for Azure VM in VMSS with Load Balancer dynamic pool

Hello JAMES MCCLELLAN,

Looks like you are trying to get inboundNatRulePortMappings from the LoadBalancer programmatically.

You could you a rest api call with the details to get the port mappings. For example:

GET  https://management.azure.com/subscriptions/{subscriptionId}/resourceGroups/{groupName}/providers/Microsoft.Network/loadBalancers/{loadBalancerName}/backendAddressPools/{backendPoolName}/queryInboundNatRulePortMapping?api-version=2024-05-01

or if it's specific to (C# code), you can refer below example code

using Azure;
using Azure.ResourceManager;
using System;
using System.Threading.Tasks;
using Azure.Core;
using Azure.Identity;
using Azure.ResourceManager.Network.Models;
using Azure.ResourceManager.Network;

// Generated from example definition: specification/network/resource-manager/Microsoft.Network/stable/2024-05-01/examples/QueryInboundNatRulePortMapping.json
// this example is just showing the usage of "LoadBalancers_ListInboundNatRulePortMappings" operation, for the dependent resources, they will have to be created separately.

// get your azure access token, for more details of how Azure SDK get your access token, please refer to https://free.blessedness.top/en-us/dotnet/azure/sdk/authentication?tabs=command-line
TokenCredential cred = new DefaultAzureCredential();
// authenticate your client
ArmClient client = new ArmClient(cred);

// this example assumes you already have this BackendAddressPoolResource created on azure
// for more information of creating BackendAddressPoolResource, please refer to the document of BackendAddressPoolResource
string subscriptionId = "subid";
string groupName = "rg1";
string loadBalancerName = "lb1";
string backendPoolName = "bp1";
ResourceIdentifier backendAddressPoolResourceId = BackendAddressPoolResource.CreateResourceIdentifier(subscriptionId, groupName, loadBalancerName, backendPoolName);
BackendAddressPoolResource backendAddressPool = client.GetBackendAddressPoolResource(backendAddressPoolResourceId);

// invoke the operation
QueryInboundNatRulePortMappingContent content = new QueryInboundNatRulePortMappingContent
{
    IPAddress = "10.0.0.4",
};
ArmOperation<BackendAddressInboundNatRulePortMappings> lro = await backendAddressPool.GetInboundNatRulePortMappingsLoadBalancerAsync(WaitUntil.Completed, content);
BackendAddressInboundNatRulePortMappings result = lro.Value;

Console.WriteLine($"Succeeded: {result}");

For other language examples, please refer: https://free.blessedness.top/en-us/rest/api/load-balancer/load-balancers/list-inbound-nat-rule-port-mappings?view=rest-load-balancer-2024-05-01&tabs=dotnet#query-inbound-nat-rule-port-mapping