Unix socket not deleted at startup in Blazor.DevServer

[Socolin]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

Hello

I want to use nginx as frontend to be able to use a TLS certificate with a specific hostname on linux, I would like to use a unix socket instead of assigning a port, to avoid possible conflict, and since the nginx configuration is static I cannot assign port dynamically.

Expected Behavior

The unix socket should be deleted if it exists at startup

Steps To Reproduce

ASPNETCORE_URLS=http://unix:/var/run/app/app.sock dotnet run

Exceptions (if any)

Unhandled exception. System.IO.IOException: Failed to bind to address http://unix:/var/run/app/app.sock: address already in use.
 ---> Microsoft.AspNetCore.Connections.AddressInUseException: Address already in use
 ---> System.Net.Sockets.SocketException (98): Address already in use
   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()
   --- End of inner exception stack trace ---
   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__DisplayClass30_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)
   --- End of inner exception stack trace ---
   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.Internal.AddressBinder.AddressesStrategy.BindAsync(AddressBindContext context, CancellationToken cancellationToken)
   at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.AddressBinder.BindAsync(IEnumerable`1 listenOptions, AddressBindContext context, 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.GenericWebHostService.StartAsync(CancellationToken cancellationToken)
   at Microsoft.Extensions.Hosting.Internal.Host.StartAsync(CancellationToken cancellationToken)
   at Microsoft.Extensions.Hosting.HostingAbstractionsHostExtensions.RunAsync(IHost host, CancellationToken token)
   at Microsoft.Extensions.Hosting.HostingAbstractionsHostExtensions.RunAsync(IHost host, CancellationToken token)
   at Microsoft.Extensions.Hosting.HostingAbstractionsHostExtensions.Run(IHost host)
   at Microsoft.AspNetCore.Components.WebAssembly.DevServer.Program.Main(String[] args)

.NET Version

7.0.100

Anything else?

No response

[javiercn]

@Socolin thanks for contacting us.

@halter73 @Tratcher can you help here? I do not think we are doing anything wrong in our setup, but I might be wrong.

[Socolin]

I forgot to mention I was using dotnet watch run and problem occurs on reload

[Tratcher]

I want to use nginx as frontend to be able to use a TLS certificate with a specific hostname on linux,

Kestrel can do that without nginx... Is there any other reason you need nginx?

[Socolin]

Kestrel cannot listen on port 80 / 443 without root permission

[Tratcher]

Neither can nginx?

[Socolin]

Nginx run as root in background I don't need to start it from my IDE thus my IDE do not run as root (which would be very bad on a security level).

Nginx communicate with a unix socket, a file with the right permission to allow only my user to create it and only nginx to read connect to it.
This is common on linux, for example php-fpm works like this too.

Also even if I could start kestrel on port 80/443 as non root by changing the config with sysctl (I think net.ipv4.ip_unprivileged_port_start would allow me to do that, but I don't think this would be a good idea anyway) I'm having multiple services running and nginx is also doing the dispatch depending on the hostname to the right host.

Since I´m working on different projects, having numeric port is not an options, I don't want to start managing excel with what port use what project and what avoid conflict with other services. With a unix socket, all this disapear

If this can help to understand how my setup is working I did a little graph, if you need more information let me know. If you have a better idea I'll be happy to hear it too. But here I'm using nginx exactly as people are using IIS on windows.

[adityamandaleeka]

Triage: we should investigate and try to reproduce this issue. Perhaps this may happen if the socket isn't Disposed (i.e. gracefully closed).

[javiercn]

@adityamandaleeka I am removing the Blazor tag since I do not think this is very related to Blazor, but feel free to add it back if you need our input or we can assist in any way.