wslc: host.wslc.internal does not resolve in musl-based containers, resolves in glibc-based containers #41769

Windows Version

Microsoft Windows [Version 10.0.26200.9457]

WSL Version

3.0.1.0

Are you using WSL 1 or WSL 2?

• WSL 2
• WSL 1

Kernel Version

6.18.40.1-1

Distro Version

wslc 3.0.1.0

Other Software

No response

Repro Steps

1. Run a name lookup for host.wslc.internal in an Alpine-based container:

   wslc run --rm python:3-alpine python3 -c "import socket; print(socket.getaddrinfo('host.wslc.internal', 80, type=socket.SOCK_STREAM))"
   

2. Run the same lookup in a Debian-based container:

   wslc run --rm python:3-slim python3 -c "import socket; print(socket.getaddrinfo('host.wslc.internal', 80, type=socket.SOCK_STREAM))"
   

Expected Behavior

Both commands print an address for host.wslc.internal.

The settings template generated by wslc describes session.hostLoopback as "DNS name that resolves to the host loopback address (default: host.wslc.internal)".

Actual Behavior

python:3-alpine fails with socket.gaierror:

Traceback (most recent call last):
  File "<string>", line 1, in <module>
    import socket; print(socket.getaddrinfo('host.wslc.internal', 80, type=socket.SOCK_STREAM))
                         ~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.14/socket.py", line 989, in getaddrinfo
    for res in _socket.getaddrinfo(host, port, family, type, proto, flags):
               ~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
socket.gaierror: [Errno -2] Name does not resolve

python:3-slim resolves the name:

[(<AddressFamily.AF_INET: 2>, <SocketKind.SOCK_STREAM: 1>, 6, '', ('169.254.73.254', 80))]

Diagnostic Logs

WslLogs-2026-10-02_10-22-27.tar.gz, collected with collect-wsl-logs.ps1 (default profile) while running both commands from Repro Steps.