Run cc-shim in the network namespace of pod

[miaoyq]

Now, the container pid that is get by docker inspect -f '{{.State.Pid}}' [container_id] is the pid of shim process, and the shim process is in the host netwok namespace.

In some case, we should get the netwok namespace of container via the container pid (e.g. dockershim),
This PR moves the shim process into the pod network namespace like VM procewss.

Fixes #615
Related to clearcontainers/runtime#987 (comment)

/cc @sboeuf @sameo @plutoinmii

Signed-off-by: Yanqiang Miao [email protected]

[sboeuf]

The change looks good globally but I have a few comments.
Also, could you improve your git commit by being more verbose, explaining why this change is needed and what it does. Same thing for the PR description.
The commit message is very important since I expect we can understand the reasons behind this commit without the need to go read the issue on Github.

[sboeuf]

Not needed since the pod structure holds the storage interface.

[sboeuf]

Replace with:

netNS, err := pod.storage.fetchPodNetwork(pod.ID())

[sboeuf]

I think this looks good but you could simplify it this way:

if err := pod.network.run(netNS.NetNsPath, func() (shimErr error) {
        pid, shimErr = shim.start(*pod, shimParams)
}); err != nil {
        return nil, err
}

[miaoyq]

@sboeuf Thanks for your review. Will address your comments.

[miaoyq]

@sboeuf Done. PTAL

[sameo]

LGTM