Samarthya

Reference

• https://kubernetes.io/docs/concepts/scheduling-eviction/taint-and-toleration/
• https://kubernetes.io/docs/concepts/scheduling-eviction/taint-and-toleration/#example-use-cases

Before we understand the tainting we should know about the Node Affinity. It the by the virtue of Affinity that pods attracts nodes as a preference or as a basic requirement.

Tainting is the exact opposite – To repel a node from scheduling a pod.

taint node ip-10-0-1-103 node-type=prod:NoSchedule

In the case above a taint is placed for Node identified by ip-10-0-1-103. The taint has a key value and effect as evident in above example.

• node-type
• prod
• NoSchedule

You can specify toleration for the pod as in the example below

apiVersion: apps/v1
kind: Deployment
metadata:
  name: my-prod
spec:
  replicas: 1
  selector:
    matchLabels:
      app: my-prod
  template:
    metadata:
      labels:
        app: my-prod
    spec:
      containers:
      - args:
        - sleep
        - "3600"
        image: busybox
        name: main
      tolerations:
      - key: node-type
        operator: Equal
        value: prod
        effect: NoSchedule                    

The operator can be exists or equal for the mentioned example

Environment

K GET NODES

NAME            STATUS   ROLES    AGE   VERSION
ip-10-0-1-101   Ready    master   38m   v1.13.3
ip-10-0-1-102   Ready    <none>   38m   v1.13.3
ip-10-0-1-103   Ready    <none>   38m   v1.13.3