deployment without central controller

[pohly]

For CSI drivers which manage local storage it is difficult to provide dynamic provisioning support because the central driver instance needs some way of communicating with the driver instance on each node. It would be nice if:

• external-provisioner could be deployed on each node together with the CSI driver
• These external-provisioner instances collaborated with each other on provisioning of PVCs, with support for late binding and immediate binding.

[pohly]

/kind feature

A previous prototype for late binding support was posted in #367

[pohly]

Immediate binding is harder. Two approaches are possible:

• leader election
• Let all instances try to set the "selected node" annotation: the one who wins owns the PVC.

The second approach is very simple to implement, I have a prototype. it simply builds on top of the work for late binding.

The leader election approach is harder to implement because the leader election helper code needs to be extended.

Performance characteristics will be different; it's not obvious whether either of the two approaches is consistently better than the other.