Eviction

Eviction initiates an eviction process, which should ideally result in a graceful eviction of a .spec.target (e.g. termination of a pod).

The evictionrequest-controller observes intents of all EvictionRequests and transforms them into Evictions. It manages the Eviction lifecycle. Requesters are preserved in .status.requesters even after they have withdrawn their request. If all requesters withdraw their eviction intent for a common target, the eviction will be canceled. Once all EvictionRequest corresponding to this Eviction .spec.target have been removed, this Eviction object will eventually be garbage collected.

If the target is a pod, the .status.targetResponders is populated from Pod's .spec.evictionResponders.

Responders should observe and communicate through the .status to help with the eviction of the target when they see their state == Active in .status.targetResponders. ResponderStatus struct should then be periodically updated to indicate the progress or completion of the eviction process by each responder in .status.responders. If .status.responders[].heartbeatTime is not updated within the heartbeat deadline defined by the Eviction API (currently 20 minutes), the eviction is passed over to the next responder with a lower priority.

If there are no other responders and the target is a pod, the last default imperative-eviction.k8s.io/evictor responder with a priority of 100 will evict the pod using the imperative Eviction API (pods/<name>/eviction subresource).

EvictionRequest

EvictionRequest defines a request that should ideally result in a graceful eviction of a .spec.target (e.g. termination of a pod).

The evictionrequest-controller observes intents of all EvictionRequests and transforms them into Evictions.

• .spec.requester is set as a label on the Eviction for easier lookup.
• Each target can have a set of responders assigned to it. Eviction objects are observed by these responders, who implement the eviction logic and update the Eviction's status with progress.

There is many-to-many relationship between EvictionRequests and Evictions in general. And many-to-one if the target is a pod.

If all requesters withdraw their eviction intent for a common target, the eviction will be canceled. Deleting an EvictionRequest also counts as a withdrawal. Once all EvictionRequest of a target are removed, the corresponding Evictions are eventually garbage collected.