change shared mounts for /var/lib/kubelet to rw

[DorianGray]

It turns out that on docker 1.10+, shared mounts and kubernetes don't play well together. Luckily, falling back to rw seems to fix it. I am not sure why hyperkube suggests a shared mount for this, but the cluster seems to work with it being rw instead. Again, this is on hypriotos.

kubernetes/kubernetes#18239

[DorianGray]

It has something to do with namespace propagation, there is a PR in kubernetes to fix it but unfortunately it hasn't been merged yet.

[DorianGray]

I just found the discussion in #40. would slave be a better mode?

[luxas]

A shared mount is required, and it's the solution, not the problem as discussed in #40.
It doesn't work with slave or any other option.
See https://www.kernel.org/doc/Documentation/filesystems/sharedsubtree.txt why.

kubelet needs to mount tmpfses (service account certificates) and other volumes, although it isn't in the same namespace, therefore it needs a shared mount.

[DorianGray]

weird, shared doesn't work on my setup...keeps saying that it's not a shared mount and causing hyperkube to get realmad.

[DorianGray]

I'll do some more tinkering, see if I can figure it out.

[luxas]

You'll have to set MountFlags= in docker.service and the dropins, then it'll work