[Question]: Microsoft-hosted ubuntu-latest and E2E test using Kestrel and CustomWebApplicationFactory

[meriturva]

Describe your question

We are trying to run a few e2e tests using Playwright and Kestrel without success.

Here is a simple WebApplicationFactory that starts Kestrel on the Microsoft-hosted agent ubuntu-latest:

protected override TestServer CreateServer(IWebHostBuilder builder)
{
    .....
    //Real TCP port
    builder.UseKestrel(x => x.Listen(IPAddress.Parse("127.0.0.1"), 51234));

    _externalHost = builder.Build();
    _externalHost.Start();
    
    ......
}

Error we have using ubuntu-latest is:

Error Message:
   Class fixture type 'xxxx.Identity.E2ETests.CustomWebApplicationFactory' threw in InitializeAsync
---- System.Net.Sockets.SocketException : Permission denied
  Stack Trace:
  
----- Inner Stack Trace -----
   at System.Net.Sockets.Socket.DoBind(EndPoint endPointSnapshot, SocketAddress socketAddress)
   at System.Net.Sockets.Socket.Bind(EndPoint localEP)
   at Microsoft.AspNetCore.Server.Kestrel.Transport.Sockets.SocketTransportOptions.CreateDefaultBoundListenSocket(EndPoint endpoint)
   at Microsoft.AspNetCore.Server.Kestrel.Transport.Sockets.SocketConnectionListener.Bind()
   at Microsoft.AspNetCore.Server.Kestrel.Transport.Sockets.SocketTransportFactory.BindAsync(EndPoint endpoint, CancellationToken cancellationToken)
   at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Infrastructure.TransportManager.BindAsync(EndPoint endPoint, ConnectionDelegate connectionDelegate, EndpointConfig endpointConfig, CancellationToken cancellationToken)
   at Microsoft.AspNetCore.Server.Kestrel.Core.KestrelServerImpl.<>c__DisplayClass28_0`1.<<StartAsync>g__OnBind|0>d.MoveNext()
--- End of stack trace from previous location ---
   at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.AddressBinder.BindEndpointAsync(ListenOptions endpoint, AddressBindContext context, CancellationToken cancellationToken)
   at Microsoft.AspNetCore.Server.Kestrel.Core.ListenOptions.BindAsync(AddressBindContext context, CancellationToken cancellationToken)
   at Microsoft.AspNetCore.Server.Kestrel.Core.AnyIPListenOptions.BindAsync(AddressBindContext context, CancellationToken cancellationToken)
   at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.AddressBinder.EndpointsStrategy.BindAsync(AddressBindContext context, CancellationToken cancellationToken)
   at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.AddressBinder.BindAsync(ListenOptions[] listenOptions, AddressBindContext context, Func`2 useHttps, CancellationToken cancellationToken)
   at Microsoft.AspNetCore.Server.Kestrel.Core.KestrelServerImpl.BindAsync(CancellationToken cancellationToken)
   at Microsoft.AspNetCore.Server.Kestrel.Core.KestrelServerImpl.StartAsync[TContext](IHttpApplication`1 application, CancellationToken cancellationToken)
   at Microsoft.AspNetCore.Hosting.WebHost.StartAsync(CancellationToken cancellationToken)
   at Microsoft.AspNetCore.Hosting.WebHost.Start()

The anomaly is that we very often use Testcontainers for our integration tests without encountering any issues with port binding. Why do we run into these problems when using Kestrel for our E2E test?

Locally, everything works like a charm.

Thanks

Versions

Ubuntu-latest

Environment type (Please select at least one enviroment where you face this issue)

• Self-Hosted
• Microsoft Hosted
• VMSS Pool
• Container

Azure DevOps Server type

dev.azure.com (formerly visualstudio.com)

Operation system

Ubuntu latest

Version controll system

No response

Azure DevOps Server Version (if applicable)

No response