whentimeslows/website
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

Docs for pod deletion cost feature

Browse Source
This commit is contained in:
Abdullah Gharaibeh
2021-03-10 14:31:32 -05:00
parent d0544c2f64
commit 290a652991
3 changed files with 43 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files
content/en/docs/concepts/workloads/controllers/replicaset.md
+30
View File
@@ -321,6 +321,36 @@ prioritize scaling down pods based on the following general algorithm:
If all of the above match, then selection is random.
### Pod deletion cost
{{< feature-state for_k8s_version="v1.21" state="alpha" >}}
Using the [`controller.kubernetes.io/pod-deletion-cost`](/docs/reference/command-line-tools-reference/labels-annotations-taints/#pod-deletion-cost)
annotation, users can set a preference regarding which pods to remove first when downscaling a ReplicaSet.
The annotation should be set on the pod, the range is [-2147483647, 2147483647]. It represents the cost of
deleting a pod compared to other pods belonging to the same ReplicaSet. Pods with lower deletion
cost are preferred to be deleted before pods with higher deletion cost.
The implicit value for this annotation for pods that don't set it is 0; negative values are permitted.
Invalid values will be rejected by the API server.
This feature is alpha and disabled by default. You can enable it by setting the
[feature gate](/docs/reference/command-line-tools-reference/feature-gates/)
`PodDeletionCost` in both kube-apiserver and kube-controller-manager.
{{< note >}}
- This is honored on a best-effort basis, so it does not offer any guarantees on pod deletion order.
- Users should avoid updating the annotation frequently, such as updating it based on a metric value,
because doing so will generate a significant number of pod updates on the apiserver.
{{< /note >}}
#### Example Use Case
The different pods of an application could have different utilization levels. On scale down, the application
may prefer to remove the pods with lower utilization. To avoid frequently updating the pods, the application
should update `controller.kubernetes.io/pod-deletion-cost` once before issuing a scale down (setting the
annotation to a value proportional to pod utilization level). This works if the application itself controls
the down scaling; for example, the driver pod of a Spark deployment.
### ReplicaSet as a Horizontal Pod Autoscaler Target
A ReplicaSet can also be a target for