Container network namespace not visible for ip netns ...

[arnegroskurth]

Description

Network namespaces created for containers are not visible for the ip netns ... commands as they (or their filesystem-representation) are not created/present under /var/run/netns/ but in the non-standard /var/run/docker/netns/ directory.

This can be quite annoying when debugging more complex container networking layouts and many users seem to help themselves by manually creating appropriate symlinks (e.g. here, here and here)

Is there a reason to diverge from the standard path?

Steps to reproduce the issue:

1. Start any container
2. Note empty output of ip netns list

Describe the results you received:

An empty output of ip netns list.

Describe the results you expected:

See the network namespace associated with the container.

Output of docker version:

Docker version 20.10.2, build 20.10.2-0ubuntu1~20.04.2