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Update DaemonSet scheduling version inconsistency #17476

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Update DaemonSet scheduling version inconsistency #17476

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bcfaf54
Update DaemonSet scheduling version inconsistency
christophercarney Nov 7, 2019
79a23f0
Clean-up default behavior of DaemonSet scheduling
christophercarney Nov 12, 2019
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21 changes: 11 additions & 10 deletions content/en/docs/concepts/workloads/controllers/daemonset.md
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Expand Up @@ -112,22 +112,23 @@ when the Pod is created, so it is ignored by the scheduler). Therefore:
- The DaemonSet controller can make Pods even when the scheduler has not been started, which can help cluster
bootstrap.

However, by using the DaemonSet controller to schedule the DaemonSet pods that
it creates introduces the following issues:

- Inconsistent Pod behavior: Normal Pods waiting to be scheduled are created
and in `Pending` state, but DaemonSet pods are not created in `Pending`
state. This is confusing to the user.
- [Pod preemption](/docs/concepts/configuration/pod-priority-preemption/)
is handled by default scheduler. When preemption is enabled, the DaemonSet controller
will make scheduling decisions without considering pod priority and preemption.

### Scheduled by default scheduler (enabled by default since 1.12)

{{< feature-state state="beta" for-kubernetes-version="1.12" >}}

A DaemonSet ensures that all eligible nodes run a copy of a Pod. Normally, the
node that a Pod runs on is selected by the Kubernetes scheduler. However,
DaemonSet pods are created and scheduled by the DaemonSet controller instead.
That introduces the following issues:

* Inconsistent Pod behavior: Normal Pods waiting to be scheduled are created
and in `Pending` state, but DaemonSet pods are not created in `Pending`
state. This is confusing to the user.
* [Pod preemption](/docs/concepts/configuration/pod-priority-preemption/)
is handled by default scheduler. When preemption is enabled, the DaemonSet controller
will make scheduling decisions without considering pod priority and preemption.
node that a Pod runs on is selected by the Kubernetes scheduler. This is also
the default behavior of DaemonSet pods.

`ScheduleDaemonSetPods` allows you to schedule DaemonSets using the default
scheduler instead of the DaemonSet controller, by adding the `NodeAffinity` term
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