Create symlinks for network namespaces inside docker containers

linkns.sh

#!/bin/bash

# This simple script creates symlinks for network namespaces of docker containers,
# then you can interact to that network namespace with built-in iproute2 on linux.
# See iproute2 convention in: http://man7.org/linux/man-pages/man8/ip-netns.8.html

container_ids=`docker ps -aq`

for cid in $container_ids
do
  pid=`docker inspect -f '{{.State.Pid}}' $cid`
  if [ ! -f "/var/run/netns/$cid" ]; then
          ln -s /proc/$pid/ns/net /var/run/netns/$cid
  fi

  echo "=================== Check network namespaces ==============="
  ip netns exec $cid ip addr show eth0
done