We'd like to graduate node and pod affinity to Beta in 1.4.

Beta

• Change annotation key from scheduler.alpha.kubernetes.io/affinity to scheduler.beta.kubernetes.io/affinity
• Make performance of pod affinity acceptable (Fix performance problem of pod affinity #26144) (and verify that performance of node affinity is acceptable)
• Better solution for "first pod problem"
• Last bullet point here Inter pod topological affinity and anti-affinity implementation #22985 (comment)
• Before allowing users to use it, be sure we won't need to roll back to binary version that doesn't support it
• Re-enable/fix all tests (see e.g. Disable PodAffinity SchedulerPredicates test #26697, PodAffinity SchedulerPredicates are not well isolated #26698)

v1

• Move Affinity to be a field in PodSpec
• Implement RequiredDuringExecution
• Incorporate feedback from users of Beta

Better solution for DoS issues? (or just rely on priority/preemption when we have it?) (see #18265 (comment))

cc/ @kevin-wangzefeng @bgrant0607 @wojtek-t

ref/ #18261 #18265 #24853 #22985 #19758