Kubernetes Taint and Toleration

CozyFex included in kubernetes k8s orchestration

2021-05-10 311 words 2 minutes

Contents

You must know

Taint and Toleration

Usually it uses not to bind PODs to specific Node.
For example, there’s a Node that has GPU resources then you want not to bind PODs that don’t need GPU resources.
At this time, you can use taint and toleration.

Taint

taint

taint is to apply to the Node.

Commands

_{Add taint command structure}

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kubectl taint nodes [node-name] [key]=[value]:[taint-effect]

Name	Example
[node-name]	node01
[key]	app
[value]	myapp
[taint-effect]	NoSchedule / PreferNoSchedule / NoExecute

_{Add taint}

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kubectl taint nodes node01 app=myapp:NoSchedule

_{Remove taint}

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# Focus on tailing dash(-)
kubectl taint nodes node01 app=myapp:NoSchedule-

Taint Effect

NoSchedule

If there’s no toleration in the PODSpec, the scheduler does not bind the POD to the Node.
It’s not affect to exist PODs.

PreferNoSchedule

If there’s no toleration in the PODSpec, the scheduler try not to bind the POD to the Node, but it’s not a necessary.
There’s not enough resources on the cluster, the scheduler could bind the POD to the Node that has taint.

NoExecute

If there’s no toleration in the PODSpec, the scheduler does not bind the POD to the Node.
The exists PODs that don’t have toleration are terminated.

Toleration

tolerations

tolerations is to set PODs.
In the tolerations definitions, you need to set double quotes(") for the values.

POD YAML

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apiVersion: v1
kind: Pod
metadata:
  name: myapp-pod
spec:
  containers:
    - name: nginx-container
      image: nginx
  tolerations:
    - key: "app"
      operator: "Equal"
      value: "myapp"
      effect: "NoSchedule"

operator

Equal
If the operator is Equal, the value must set same value of the taint.
Exists
If the operator is Exists, you must not define the value.

When taint and tolerations matched

`operator` = `Equal`

taint	tolerations
key	key
value	value
taint-effect	effect

`operator` = `Exists`

taint	tolerations
key	key
taint-effect	effect

Contents

Kubernetes Taint and Toleration

You must know

Taint

Commands

Taint Effect

Toleration

POD YAML

operator

When taint and tolerations matched

operator = Equal

operator = Exists

`operator` = `Equal`

`operator` = `Exists`