aspnetcore: Unix socket not cleaned up on exit

Describe the bug

I hit a similar issue in 2015 (https://github.com/aspnet/KestrelHttpServer/issues/419) and I think it’s still lingering today. When I shutdown the systemd service for an ASP.NET site, it won’t restart again as the UNIX socket is not deleted on shutdown. I can work around the issue by deleting the socket in Program.cs, but Kestrel should be doing this itself on shutdown.

To Reproduce

Steps to reproduce the behavior:

Created a new site using the latest ASP.NET Core 3.0 preview
Published from Visual Studio with “self-contained” deployment mode, targeting linux-x64 runtime
Created systemd unit as per https://docs.microsoft.com/en-us/aspnet/core/host-and-deploy/linux-nginx?view=aspnetcore-2.2, /etc/systemd/system/test-site.service:

[Unit]
Description=Test ASP.NET Core Site

[Service]
WorkingDirectory=/var/www/test-site/
ExecStart=/var/www/test-site/Daniel15.Test
Restart=always
# Restart service after 10 seconds if the dotnet service crashes:
RestartSec=10
KillSignal=SIGINT
SyslogIdentifier=test-site
User=www-data
Environment=ASPNETCORE_ENVIRONMENT=Production
Environment=ASPNETCORE_URLS=http://unix:/tmp/test-site.sock

[Install]
WantedBy=multi-user.target

Enable and start the unit:

sudo service test-site enable
sudo service test-site start

It works fine.

Try to restart it:

sudo service test-site restart

It fails to start:

Sep 18 23:48:34 syd02.d.sb test-site[19486]: System.IO.IOException: Failed to bind to address http://unix:/tmp/test-site.sock: a
Sep 18 23:48:34 syd02.d.sb test-site[19486]:  ---> Microsoft.AspNetCore.Connections.AddressInUseException: Address already in use
Sep 18 23:48:34 syd02.d.sb test-site[19486]:  ---> System.Net.Sockets.SocketException (98): Address already in use
Sep 18 23:48:34 syd02.d.sb test-site[19486]:    at System.Net.Sockets.Socket.UpdateStatusAfterSocketErrorAndThrowException(SocketErr
Sep 18 23:48:34 syd02.d.sb test-site[19486]:    at System.Net.Sockets.Socket.DoBind(EndPoint endPointSnapshot, SocketAddress socketA
Sep 18 23:48:34 syd02.d.sb test-site[19486]:    at System.Net.Sockets.Socket.Bind(EndPoint localEP)
Sep 18 23:48:34 syd02.d.sb test-site[19486]:    at Microsoft.AspNetCore.Server.Kestrel.Transport.Sockets.SocketConnectionListener.Bi
Sep 18 23:48:34 syd02.d.sb test-site[19486]:    --- End of inner exception stack trace ---

Expected behavior

Should restart cleanly

Additional context

dotnet --info on my computer:

λ dotnet --info
.NET Core SDK (reflecting any global.json):
 Version:   3.0.100-preview9-014004
 Commit:    8e7ef240a5

Runtime Environment:
 OS Name:     Windows
 OS Version:  10.0.18362
 OS Platform: Windows
 RID:         win10-x64
 Base Path:   C:\Program Files\dotnet\sdk\3.0.100-preview9-014004\

Host (useful for support):
  Version: 3.0.0-preview9-19423-09
  Commit:  2be172345a

.NET Core SDKs installed:
  1.0.0-preview2-003121 [C:\Program Files\dotnet\sdk]
  1.0.0-preview2-1-003177 [C:\Program Files\dotnet\sdk]
  1.0.0-rc4-004771 [C:\Program Files\dotnet\sdk]
  1.0.0 [C:\Program Files\dotnet\sdk]
  1.0.4 [C:\Program Files\dotnet\sdk]
  1.1.0 [C:\Program Files\dotnet\sdk]
  1.1.9 [C:\Program Files\dotnet\sdk]
  1.1.11 [C:\Program Files\dotnet\sdk]
  1.1.12 [C:\Program Files\dotnet\sdk]
  2.0.0 [C:\Program Files\dotnet\sdk]
  2.0.2 [C:\Program Files\dotnet\sdk]
  2.1.201 [C:\Program Files\dotnet\sdk]
  2.1.202 [C:\Program Files\dotnet\sdk]
  2.1.503 [C:\Program Files\dotnet\sdk]
  2.1.504 [C:\Program Files\dotnet\sdk]
  2.1.602 [C:\Program Files\dotnet\sdk]
  2.2.103 [C:\Program Files\dotnet\sdk]
  2.2.202 [C:\Program Files\dotnet\sdk]
  3.0.100-preview9-014004 [C:\Program Files\dotnet\sdk]

.NET Core runtimes installed:
  Microsoft.AspNetCore.All 2.1.7 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.1.8 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.1.9 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.1.12 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.2.1 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.2.3 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.App 2.1.7 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.1.8 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.1.9 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.1.12 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.2.1 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.2.3 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 3.0.0-preview9.19424.4 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.NETCore.App 1.0.0 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 1.0.3 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 1.0.4 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 1.0.5 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 1.0.11 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 1.0.13 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 1.0.14 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 1.1.0 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 1.1.1 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 1.1.2 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 1.1.8 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 1.1.10 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 1.1.11 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.0.0 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.0.7 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.0.9 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.7 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.8 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.9 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.12 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.2.1 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.2.3 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 3.0.0-preview9-19423-09 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.WindowsDesktop.App 3.0.0-preview9-19423-09 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]

To install additional .NET Core runtimes or SDKs:
  https://aka.ms/dotnet-download

On the server, it’s using a self-contained deployment so I don’t think there’s a dotnet ---info command I can run, but it’s using 3.0.0-preview9-19423-09

About this issue

Original URL
State: closed
Created 5 years ago
Comments: 27 (20 by maintainers)

Links to this issue

Most upvoted comments

Triage decision: The workaround is good enough, and we won’t be making a product change here.

shirhatti on Mar 25, 2020

@davidfowl That page you linked (https://troydhanson.github.io/network/Unix_domain_sockets.html) is interesting. Sounds like the old socket should be cleaned up on start, not on exit. That’d also handle the case where the app doesn’t exit cleanly (eg if you kill -9 it or it crashes) as @sherlock1982 mentioned in a comment.

Might be worth seeing what other frameworks do?

Daniel15 on May 11, 2020

You could cleanup the socket like this:

[Service]
ExecStartPre=/usr/bin/rm -f /tmp/test-site.sock
ExecStart=/var/www/test-site/Daniel15.Test

aramean on Mar 24, 2020

Sweet, we can close this! Thanks @tmds !

davidfowl on May 31, 2021

@shirhatti That’s unfortunate because this is very clearly a bug. An app should clean up its allocated resources when they’re no longer required. This would be similar to not fixing a memory leak because a workaround exists.

Daniel15 on Mar 29, 2020

Is it possible to mention this issue in the readme of ASP.NET Core 3.0, or perhaps just in the Kestrel docs? Anyone using it with UNIX sockets will hit this issue.

Daniel15 on Sep 23, 2019

We hit the same thing in our tests. It does feel strange that we don’t explicitly create it yet we’re responsible for deleting it. We do the same in our tests 😄 https://github.com/aspnet/AspNetCore/blob/master/src/Servers/Kestrel/test/FunctionalTests/UnixDomainSocketsTests.cs#L113 (maybe that should have been a sign).

This seems like something we should fix in 3.1 cc @anurse

davidfowl on Sep 19, 2019