CODEWITHSUNDEEP
kuberneteskubernetes-pod
flyer
flyer

Reputation: 9826

What's the difference between pod deletion and pod eviction?

From PodInterface the two operations Delete and Evict seems having the same effect: deleting the old Pod and creating a new Pod.

If the two operations have the same effect, why do we need two API to delete a Pod and create a new one?

Upvotes: 12

Views: 10518

Answers (2)

victorm1710
victorm1710

Reputation: 1523

Pod evict operation (assuming you're referring to the Eviction API) is a sort of smarter delete operation, which respects PodDisruptionBudget and thus it does respect the high-availability requirements of your application (as long as PodDisruptionBudget is configured correctly). Normally you don't manually evict a pod, however the pod eviction can be initiated as a part of a node drain operation (which can be manually invoked by kubectl drain command or automatically by the Cluster Autoscaler component).

Pod delete operation on the other hand doesn't respect PodDisruptionBudget and thus can affect availability of your application. As opposite to the evict operation this operation is normally invoked manually (e.g. by kubectl delete command).

Also besides the Eviction API, pods can be evicted by kubelet due to Node-pressure conditions, in which case PodDisruptionBudget is not respected by Kubernetes (see Node-pressure Eviction)

Upvotes: 6

Arghya Sadhu
Arghya Sadhu

Reputation: 44677

Deletion of a pod is done by an end user and is a normal activity. It means the pod will be deleted from ETCD and kubernetes control plane. Unless there is a higher level controller such as deployment, daemonset, statefulset etc the pod will not be created again and scheduled to a kubernetes worker node.

Eviction happens if resource consumption by pod is exceeded the limit and kubelet triggers eviction of the pod or a user performs kubectl drain or manually invoking the eviction API. It's generally not not a normal activity .Sometimes evicted pods are not automatically deleted from ETCD and kubernetes control plane. Unless there is a higher level controller such as deployment, daemonset, statefulset etc the evicted pod will not be created again and scheduled to a kubernetes worker node.

It's preferable to use delete instead of evict because evict comes with more risk compared to delete because eviction may lead to in some cases, an application to a broken state if the replacement pod created by the application’s controller(deployment etc.) does not become ready, or if the last pod evicted has a very long termination grace period

Upvotes: 17

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