Currently, API server is not aware of the static pods (manifests from
sources other than the API server, e.g. file and http) at all. This is
inconvenient since users cannot check the static pods through kubectl.
It is also sub-optimal because scheduler is unaware of the resource
consumption by these static pods on the node.
This change syncs the information back to the API server by creating a
mirror pod via API server for each static pod.
- Kubelet creates containers for the static pod, as it would do
normally.
- If a mirror pod gets deleted, Kubelet will re-create one. The
containers are sync'd to the static pods, so they will not be
affected.
- If a static pod gets removed from the source (e.g. manifest file
removed from the directory), the orphaned mirror pod will be deleted.
Note that because events are associated with UID, and the mirror pod has
a different UID than the original static pod, the events will not be
shown for the mirror pod when running `kubectl describe pod
<mirror_pod>`.
--sync_nodes=false gives user flexibility to add/remove nodes in the
cluster using REST api/kubectl cli and at the same time can use
cloud provider for other resources like persistent disks, etc.
This leaves `pkg/kubelet/server/server.go` looking a little ugly as there is an extra layer of "config" structs that isn't needed. This is left as a TODO for now.
Break up the monolithic volumes code in kubelet into very small individual
modules with a well-defined interface. Move them all into their own packages
and beef up testing along the way.
Added a kubelet config source for watching pods on apiserver.
The pods are converted to boundpods for merging with other
config sources.
The preferred way to create a kubelet is now to pass an apiserver
client but not an etcd client. Changed cmd/integration to use
apiserver to talk to kubelets. And cmd/kubernetes.
Unit, integration, and e2e tests pass, except for a failure of the pd
e2e test which was unrelated.
