affinity/anti-affinity](https://kubernetes.io/docs/concepts/configuration/assign-pod-node/) and **[beta]** [pod affinity/anti-affinity](https://kubernetes.io/docs/concepts/configuration/assign-pod-node/). Node affinity/anti-affinity allow you to specify rules for restricting which node(s) a pod can schedule onto, based on the labels on the node. Pod affinity/anti-affinity allow you to specify rules for spreading and packing pods relative to one another, across arbitrary topologies (node, zone, etc.) These...

- Added support to the scheduler to start using QueueingHint registered for Pod/Updated event to determine whether unschedulable Pods update make them schedulable, when the feature gate `SchedulerQueueingHints` is enabled.
  Previously, when unschedulable Pods are updated, the scheduler always put Pods back to activeQ/backoffQ. But, actually not all updates to Pods make Pods schedulable, especially considering many scheduling constraints nowadays are immutable.

- Added new option to the `InterPodAffinity` scheduler plugin to ignore existing
  pods` preferred inter-pod affinities if the incoming pod has no preferred inter-pod
  affinities. This option can be used as an optimization for higher scheduling throughput
  (at the cost of an occasional pod being scheduled non-optimally/violating existing
  pods preferred inter-pod affinities). To enable this scheduler option, set the

Jobs (instead of Pods) by default.
  * Pods can now consume Secret data in environment variables and inject those
environment variables into a container’s command-line args.
  * Stable version of Heapster which scales up to 1000 nodes: more metrics, reduced
latency, reduced cpu/memory consumption (~4mb per monitored node).
  * Pods now have a security context which allows users to specify:

    * Specifically the new controller watches the API server for scheduled pods. It processes each pod and ensures that any volumes that implement the volume Attacher interface are attached to the node their pod is scheduled to.

resources of running and terminating pods when deciding to accept new pods, since terminating pods are still holding on to those resources. This stricter handling may surface to end users as pod rejections when creating pods that are scheduled to mostly full nodes that have other terminating pods holding the resources the new pods need. The most likely error would be a pod set to `Failed` phase with reason set to `OutOfCpu` or `OutOfMemory`, but any resource on the node that has some fixed limit (including...

- There is now support for collecting pod logs under `/var/log/pods/NAMESPACE_NAME_UID` to stackdriver with `k8s_pod` resource type. ([#74502](https://github.com/kubernetes/kubernetes/pull/74502), [@Random-Liu](https://github.com/Random-Liu))

  When the scheduling queue receives a cluster event, before moving each Pod from unschedulable pod pool to activeQ/backoffQ, it will call QueueingHintFn of plugins that rejected each Pod in the previous scheduling cycle.
  Depending on the value returned from QueueingHintFn, the scheduling queue changes how it queues each Pod:
  - if more than one QueueingHintFn returns QueueImmediately, it queues Pod to activeQ.

- Fix a bug that Pods could stuck in the unschedulable pod pool 
  if they're rejected by PreEnqueue plugins that could change its result by a change in resources apart from Pods.
  
  DRA plugin is the only plugin that meets the criteria of the bug in in-tree, 
  and hence if you have `DynamicResourceAllocation` feature flag enabled, 

      * In 1.4, either that key or this key: `pods.beta.kubernetes.io/init-containers`,can be used.
    * When you GET an object, you will see both annotation keys with the same values.
      You can safely roll back from 1.4 to 1.3, and things with init-containers
      will still work (pods, deployments, etc).