Allow the user to specify the resolver configuration file that is used
to determine the default DNS parameters. This defaults to the system's
/etc/resolv.conf.
Currently, whenever there is any update, kubelet would force all pod workers to
sync again, causing resource contention and hence performance degradation.
This commit flips kubelet to use incremental updates (as opposed to snapshots).
This allows us to know what pods have changed and send updates to those pod
workers only. The `SyncPods` function has been replaced with individual
handlers, each handling an operation (ADD, REMOVE, UPDATE). Pod workers are
still triggered periodically, and kubelet performs periodic cleanup as well.
This commit also spawns a new goroutine solely responsible for killing pods.
This is necessary because pod killing could hold up the sync loop for
indefinitely long amount of time now user can define the graceful termination
period in the container spec.
We chose to use podFullName (name_namespace) as key in the status manager
because mirror pod and static pod share the same status. This is no longer
needed because we do not store statuses for static pods anymore (we only
store statuses for their mirror pods). Also, reviously, a few fixes were
merged to ensure statuses are cleaned up so that a new pod with the same
name would not resuse an old status.
This change cleans up the code by using UID as key so that the code would
become less brittle.
Getting the public IP a container is supposed to use is O(hard),
and usually involves ugly gyrations in python or with interfaces.
Using the downward API means that the IP Kube is announcing to
other endpoints is also visible inside the container for pods to
identify themselves.
This commit wires together the graceful delete option for pods
on the Kubelet. When a pod is deleted on the API server, a
grace period is calculated that is based on the
Pod.Spec.TerminationGracePeriodInSeconds, the user's provided grace
period, or a default. The grace period can only shrink once set.
The value provided by the user (or the default) is set onto metadata
as DeletionGracePeriod.
When the Kubelet sees a pod with DeletionTimestamp set, it uses the
value of ObjectMeta.GracePeriodSeconds as the grace period
sent to Docker. When updating status, if the pod has DeletionTimestamp
set and all containers are terminated, the Kubelet will update the
status one last time and then invoke Delete(pod, grace: 0) to
clean up the pod immediately.
This generalizes the handling of containers in the
ContainerManager.
Also introduces the ability to determine how much
resources are reserved for those system containers.
