Deploying Azure App Service Webjob Using .Net 6 Fails to Start "Failed to bind to address http://127.0.0.1:5000: address already in use"

Question

I ran into an issue while migrating an Azure app service from .Net Core 5 to 6 while also updating the stack configuration in Azure Portal to use .Net version ".Net 6 (LTS)". The app service only contains continuous webjobs that process service bus messages. Locally, the webjob project runs fine but when deployed to Azure it fails to start. In Kudu tools I'm presented with an error:

[01/03/2023 18:21:32 > 1b0f90: ERR ] Unhandled exception. System.IO.IOException: Failed to bind to address http://127.0.0.1:5000: address already in use.
[01/03/2023 18:21:32 > 1b0f90: ERR ]  ---> Microsoft.AspNetCore.Connections.AddressInUseException: Only one usage of each socket address (protocol/network address/port) is normally permitted.
[01/03/2023 18:21:32 > 1b0f90: ERR ]  ---> System.Net.Sockets.SocketException (10048): Only one usage of each socket address (protocol/network address/port) is normally permitted.

Eventually I am able to get past the error by applying the app setting ASPNETCORE_URLS=http://localhost:5001 to the app service, and applying the same app setting every .Net Core 6 app service running web jobs in the same app service plan except I have to increment the port to something different. This does not seem to be a problem with non-webjob applications, and only occurs when I configure the app service stack to ".Net 6 (LTS)" in Azure Portal.

My question is: Is there another workaround to this issue? I find adding unique port assignments to every webjob running .Net 6 to be a cumbersome and not ideal, and this issue will exist as a serious gotcha for future development.

Here is the dependencies I am pulling in:

Azure.Messaging.ServiceBus Version=7.11.0
Microsoft.Azure.WebJobs Version=3.0.32
Microsoft.ApplicationInsights.AspNetCore Version=2.21.0
Microsoft.ApplicationInsights.NLogTarget Version=2.21.0
Microsoft.Azure.Services.AppAuthentication Version=1.6.2
Microsoft.Azure.WebJobs.Extensions Version=4.0.1
Microsoft.Azure.WebJobs.Extensions.ServiceBus Version=5.3.0
Microsoft.Azure.WebJobs.Extensions.Storage Version=5.0.1
NLog Version=5.0.4
NLog.Targets.Seq Version=2.1.0
NLog.Web.AspNetCore Version=5.1.4

To reproduce:

1. Create two or more .Net Core 6 applications that only implement Webjobs. My Webjobs functions process Service Bus topic messages, not sure if this is important to reproduce.
2. Deploy the Webjob applications to the same App Service Plan
3. In the configuration blade settings tab for each web app make sure that the runtime stack is set to ".Net 6 (LTS)", keep the rest as default.

Now when you go to view the webjobs in Azure Portal you will see that the job is stuck in a restart cycle.

The problem seems to be around setting the stack settings version to ".Net 6 (LTS)". From this article it seems that this setting makes the app service Run Kestrel with YARP, I'm guessing the feature parity is not 1:1 with the previous stack.

Example project that can reproduce the issue can be found on Github. Follow README found in .\Scripts to deploy example to Azure. Note: there seems to be an issue with the template setting the stack to .Net 6. This may need to be done manually post deployment to fully reproduce the issue.

Answer 1

I have created 2 .NET Core 6 Applications and deployed to Azure Web Jobs in same Azure App Service.

• Make sure to enable Always On option in App Service => Configuration => General Settings to ensure WebJobs are running Continuously.

• I have updated the Stack settings run time Version to .NET 6.

Now when you go to view the webjobs in Azure Portal you will see that the job is stuck in a restart cycle.

Yes, even I got stuck with the same issue. The WebJob which I have published 2nd is showing the Pending Restart status.

When I click on the Logs, I can see the below error is Logged.

Make sure that you are setting a connection string named >`AzureWebJobsDashboard` in your Microsoft Azure Website >configuration by using the following format >`DefaultEndpointsProtocol=https;AccountName=**NAME**;Account>Key=**KEY**` pointing to the Microsoft Azure Storage account where >the Microsoft Azure WebJobs Runtime logs are stored.

• In the second Console App, I haven't Configured the WebJobs and Storage Account.
• Updated the code and published again.
• Now I can see both the Jobs are in Running State.

My Program.cs file:

// See https://aka.ms/new-console-template for more information
using System.Threading.Tasks;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;

namespace WebJobApp
{
    class Program
    {
        static async Task Main()
        {
            var builder = new HostBuilder();
            builder.UseEnvironment(EnvironmentName.Development);
            builder.ConfigureWebJobs(b =>
            {
                b.AddAzureStorageCoreServices();
                b.AddAzureStorageQueues();
            });
            builder.ConfigureLogging((context, b) =>
            {
                b.AddConsole();
            });
            var host = builder.Build();
            using (host)
            {
                await host.RunAsync();
            }
        }
    }
}

Reference taken from MSDoc.