Cannot create container when disable_new_netns=true

[jodh-intel]

$ sudo docker run -ti --runtime kata-runtime busybox true
$ sudo sed -i 's/#disable_new_netns = true/disable_new_netns = true/g' /etc/kata-containers/configuration.toml
$ sudo docker run -ti --runtime kata-runtime busybox true                                                     
docker: Error response from daemon: OCI runtime create failed: config disable_new_netns only works with 'none' internetworking_model: unknown.
$ sudo sed -i 's/internetworking_model=".*"/internetworking_model="none"/g' /etc/kata-containers/configuration.toml
$ sudo docker run -ti --runtime kata-runtime busybox true
docker: Error response from daemon: OCI runtime create failed: exit status 1: stdout: , stderr: time="2018-11-23T16:13:45Z" level=fatal msg="failed to add interface veth0b83b32 to sandbox: error setting interface \"veth0b83b32\" IP to 172.17.0.3/16: cannot program address 172.17.0.3/16 in sandbox interface because it conflicts with existing route {Ifindex: 4 Dst: 172.17.0.0/16 Src: 172.17.0.1 Gw: <nil> Flags: [] Table: 254}": unknown.

[jodh-intel]

/cc @caoruidong.

Related: #733.

[caoruidong]

This needs docker run --net=none. Anyway, it may not be very perfect.

[jodh-intel]

oh, so we need to disable it networking twice? That is confusing ;(

[jodh-intel]

For completeness, here's what you need to do to get this working:

# Yay, it works normally
$ sudo docker run -ti --runtime kata-runtime busybox true

# Let's disable new network namespaces
$ sudo sed -i 's/#disable_new_netns = true/disable_new_netns = true/g' /etc/kata-containers/configuration.toml
$ sudo sed -i 's/internetworking_model=".*"/internetworking_model="none"/g' /etc/kata-containers/configuration.toml

# Now, it works
$ sudo docker run -ti --runtime --net=none kata-runtime busybox true

[caoruidong]

disable_new_netns is tend to not create a new namesapce for qemu and shim. --net=none is tend to use a CNI plugin to manage network in k8s scenario.