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Add documentation for TaintNodesByCondition (#5352)

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* Add documentation for TaintNodesByCondition

* Update nodes.md

* Update taint-and-toleration.md

* Update daemonset.md

* Update nodes.md

* Update taint-and-toleration.md

* Update daemonset.md
This commit is contained in:
Marek Grabowski
2017-09-13 00:55:49 +01:00
committed by Steve Perry
parent 7751e73961
commit 83509afbd2
3 changed files with 49 additions and 12 deletions
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docs/concepts/configuration/taint-and-toleration.md
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@@ -188,7 +188,7 @@ running on the node as follows
The above behavior is a beta feature. In addition, Kubernetes 1.6 has alpha
support for representing node problems. In other words, the node controller
automatically taints a node when certain condition is true. The builtin taints
automatically taints a node when certain condition is true. The built-in taints
currently include:
* `node.alpha.kubernetes.io/notReady`: Node is not ready. This corresponds to
@@ -249,9 +249,20 @@ admission controller](https://git.k8s.io/kubernetes/plugin/pkg/admission/default
* `node.alpha.kubernetes.io/unreachable`
* `node.alpha.kubernetes.io/notReady`
* `node.kubernetes.io/memoryPressure`
* `node.kubernetes.io/diskPressure`
* `node.kubernetes.io/outOfDisk` (*only for critical pods*)
This ensures that DaemonSet pods are never evicted due to these problems,
which matches the behavior when this feature is disabled.
## Taint Nodes by Condition
Version 1.8 introduces an alpha feature that causes the node controller to create taints corresponding to
Node conditions. When this feature is enabled, the scheduler does not check conditions; instead the scheduler checks taints. This assures that conditions don't affect what's scheduled onto the Node. The user can choose to ignore some of the Node's problems (represented as conditions) by adding appropriate Pod tolerations.
To make sure that turning on this feature doesn't break DaemonSets, starting in version 1.8, the DaemonSet controller automatically adds the following `NoSchedule` tolerations to all daemons:
* `node.kubernetes.io/memory-pressure`
* `node.kubernetes.io/disk-pressure`
* `node.kubernetes.io/out-of-disk` (*only for critical pods*)
The above settings ensure backward compatibility, but we understand they may not fit all user's needs, which is why
cluster admin may choose to add arbitrary tolerations to DaemonSets.