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If you are developing Azure Functions in an enterprise environment, you may be in a situation where you have no direct internet access and must send all your traffic to a web proxy. When you create the ServiceBusClient yourself, you have the option of specifying the proxy using the ServiceBusClientOptions class as demonstrated below.

string connectionString = "";
string webProxyAddress = "http://127.0.0.1:3128";

ServiceBusClientOptions clientOptions = new ServiceBusClientOptions()
{
    TransportType = ServiceBusTransportType.AmqpWebSockets,
    WebProxy = new WebProxy(webProxyAddress)
};
ServiceBusClient serviceBusClient = new ServiceBusClient(connectionString, clientOptions);

However, when using an Azure Function, triggered by the Service Bus you do not have the option to provide ServiceBusClientOptions, and the ServiceBusTrigger does not allow you to provide the proxy configuration either.

[FunctionName("ServiceBusTriggeredFunction")]
public void Run(
    [ServiceBusTrigger("myqueue", Connection = "ServiceBusConnection")]string myQueueItem,
    ILogger log)
{
    log.LogInformation($"Processed message: {myQueueItem}");
}

Luckily, the Microsoft.Azure.WebJobs.Extensions.ServiceBus library, which implements the Service Bus trigger will obtain the AzureFunctionsJobHost:extensions:ServiceBus section of your Function’s configuration and use it to configure the proxy (amongst other settings) of the underlying ServiceBusClient used by the trigger. The configuration binding is handled by ServiceBusHostBuilderExtensions.

Therefore, we can make the ServiceBusTrigger use the proxy by setting the AzureFunctionsJobHost:extensions:ServiceBus:WebProxy property to the address and the port of your proxy in your local.settings.json file:

local.settings.json

{
    "IsEncrypted": false,
    "Values": {
        "AzureWebJobsStorage": "UseDevelopmentStorage=true",
        "FUNCTIONS_WORKER_RUNTIME": "dotnet",
        "ServiceBusConnection": "<NAMESPACE CONNECTION STRING>",
        // PROXY
        "AzureFunctionsJobHost:extensions:ServiceBus:WebProxy": "http://127.0.0.1:3128",
        // USE PORT 443 INSTEAD OF 5671
        "AzureFunctionsJobHost:extensions:ServiceBus:TransportType": "AmqpWebSockets"
    }
}

Additionally, if your proxy does not allow you to use the AMPQS port (5671), you can configure the Service Bus client to use AMQP over Web Sockets (which uses port 443) by setting the AzureFunctionsJobHost:extensions:ServiceBus:TransportType property to AmqpWebSockets.

Updated:

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