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Merge pull request #4173 from x13n/docs 

Document DaemonSet eviction opt in/out behavior
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Kubernetes Prow Robot 2021-07-02 06:00:13 -07:00 committed by GitHub
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cluster-autoscaler/FAQ.md
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@ -32,6 +32,7 @@ this document:
* [How can I scale a node group to 0?](#how-can-i-scale-a-node-group-to-0)
* [How can I prevent Cluster Autoscaler from scaling down a particular node?](#how-can-i-prevent-cluster-autoscaler-from-scaling-down-a-particular-node)
* [How can I configure overprovisioning with Cluster Autoscaler?](#how-can-i-configure-overprovisioning-with-cluster-autoscaler)
* [How can I enable/disable eviction for a specific DaemonSet](#how-can-i-enabledisable-eviction-for-a-specific-daemonset)
* [Internals](#internals)
* [Are all of the mentioned heuristics and timings final?](#are-all-of-the-mentioned-heuristics-and-timings-final)
* [How does scale-up work?](#how-does-scale-up-work)
@ -434,6 +435,30 @@ spec:
serviceAccountName: cluster-proportional-autoscaler-service-account
```
### How can I enable/disable eviction for a specific DaemonSet
Cluster Autoscaler will evict DaemonSets based on its configuration, which is
common for the entire cluster. It is possible, however, to specify the desired
behavior on a per pod basis. All DaemonSet pods will be evicted when they have
the following annotation.
```
"cluster-autoscaler.kubernetes.io/enable-ds-eviction": "true"
```
It is also possible to disable DaemonSet pods eviction expicitly:
```
"cluster-autoscaler.kubernetes.io/enable-ds-eviction": "false"
```
Note that this annotation needs to be specified on DaemonSet pods, not the
DaemonSet object itself. In order to do that for all DaemonSet pods, it is
sufficient to modify the pod spec in the DaemonSet object.
This annotation has no effect on pods that are not a part of any DaemonSet.
****************
# Internals
@ -512,6 +537,17 @@ What happens when a non-empty node is terminated? As mentioned above, all pods s
elsewhere. Cluster Autoscaler does this by evicting them and tainting the node, so they aren't
scheduled there again.
DaemonSet pods may also be evicted. This can be configured separately for empty
(i.e. containing only DaemonSet pods) and non-empty nodes with
`--daemonset-eviction-for-empty-nodes` and
`--daemonset-eviction-for-occupied-nodes` flags, respectively. Note that the
default behavior is different on each flag: by default DaemonSet pods eviction
will happen only on occupied nodes. Individual DaemonSet pods can also
explicitly choose to be evicted (or not). See [How can I enable/disable eviction
for a specific
DaemonSet](#how-can-i-enabledisable-eviction-for-a-specific-daemonset) for more
details.
Example scenario:
Nodes A, B, C, X, Y.
@ -690,6 +726,8 @@ The following startup parameters are supported for cluster autoscaler:
| `skip-nodes-with-system-pods` | If true cluster autoscaler will never delete nodes with pods from kube-system (except for DaemonSet or mirror pods) | true
| `skip-nodes-with-local-storage`| If true cluster autoscaler will never delete nodes with pods with local storage, e.g. EmptyDir or HostPath | true
| `min-replica-count` | Minimum number or replicas that a replica set or replication controller should have to allow their pods deletion in scale down | 0
| `daemonset-eviction-for-empty-nodes` | Whether DaemonSet pods will be gracefully terminated from empty nodes | false
| `daemonset-eviction-for-occupied-nodes` | Whether DaemonSet pods will be gracefully terminated from non-empty nodes | true
# Troubleshooting: