Prior to this commit the YAML manifests used to install the descheduler
Job and CronJob did not set container requests or limits. This is
considered an anti-pattern when deploying applications on k8s.
Set descheduler container resources to make it a burstable pod. This
will ensure a high quality experience for end users when deploying
descheduler into their clusters using the instructions from the README.
The values choosen for CPU/Memory are not based on any real data.
This adds a strategy to balance pod topology domains based on the scheduler's
PodTopologySpread constraints. It attempts to find the minimum number of pods
that should be sent for eviction by comparing the largest domains in a topology
with the smallest domains in that topology.
The k8s project recently cut over to the new official k8s.gcr.io
container registry. The descheduler image can now be pulled from
k8s.gcr.io. This is just a new DNS name for the container registry. The
previously documented DNS names for the registry still work, but
require more typing.
Based on feedback during code review it was recommended to allow
updating events in addition to creating events. Because event proceeding
logic on the client side sometimes updates existing events instead of
creating a new one.
The descheduler creates a k8s event for each pod that it evicts. When
the code to create events was added the RBAC ClusterRole was not updated
to allow creating events. Users would see the below error in the
descheduler log when it tried to create an event.
"system:serviceaccount:kube-system:descheduler-sa" cannot create resource
"events" in API group "" in the namespace "xxxx-production"' (will not retry!)'
This change fixes this error by updating the ClusterRole to allow
creation of k8s events.
Change the Job and CronJob YAML manifests to use container image
registry us.gcr.io/k8s-artifacts-prod/descheduler. This is the new
official location for the descheduler container image that is very close
to being all setup.
The k8s YAML manifests for deploying the descheduler as a k8s job were
duplicated across the "examples" and "kubernetes" directories and also
in README.md. This change consolidates the YAML manifests into the
"kubernetes" directory and simplifies the installation instructions for end
users in README.md.
Additionally a k8s CronJob has been added.
