CODEWITHSUNDEEP
kubectl
Pankaj Gupta
Pankaj Gupta

Reputation: 91

How to list only nodes which are master from kubectl output?

]$ kubectl get nodes
NAME                            STATUS                     ROLES    AGE    VERSION
ip<IP>.ec2.internal   Ready                      master   300d   v1.15.3
ip<IP>.ec2.internal   Ready                      node     180d   v1.15.3
ip<IP>.ec2.internal   Ready                      master   300d   v1.15.3
ip<IP>.ec2.internal   Ready                      node     300d   v1.15.3
ip<IP>.ec2.internal   Ready                      node     300d   v1.15.3
ip<IP>.ec2.internal   Ready,SchedulingDisabled   node     180d   v1.15.3
ip<IP>.ec2.internal   Ready                      node     180d   v1.15.3
ip<IP>.ec2.internal   Ready                      master   300d   v1.15.3
ip<IP>.ec2.internal   Ready                      node     300d   v1.15.3

What I want is the output should have only list of node name showing which is first column and which are master only. I tried the script way:

#!/bin/bash
kubectl get nodes --selector=node-role.kubernetes.io/master > nodelist.txt
cat nodelist.txt
while IFS=" " read -r f1
do
 echo $f1
done < nodelist.txt

, But I want any method using kubectl --custom-column or json filtering plz suggest.

Upvotes: 1

Views: 3227

Answers (4)

palmasd1
palmasd1

Reputation: 53

kubectl get nodes -o 'json' | jq -r '.items[] | [.metadata.name] | @tsv'

Upvotes: 0

Vit
Vit

Reputation: 8451

Also you can use labels and jsonpath to select anything you need from kubectl get nodes -o json output

kubectl get nodes -l node-role.kubernetes.io/master -o 'jsonpath={.items[*].metadata.name}'

btw, you could you kubernetes kubectl Cheat Sheet if you lost at any point. It has most frequently used commands

Upvotes: 5

Jonas
Jonas

Reputation: 128857

But I want any method using kubectl --custom-column or json filtering plz suggest.

Yes, you can use a --custom-columns to only show the name

kubectl get nodes -o custom-columns=NAME:.metadata.name
NAME
my-node

In addition, you can omit the headers using --no-headers

kubectl get nodes -o custom-columns=NAME:.metadata.name --no-headers
my-node

Using the selector you provided, to only show master nodes, the full command is this:

kubectl get nodes --selector=node-role.kubernetes.io/master -o custom-columns=NAME:.metadata.name --no-headers

Upvotes: 0

aekiratli
aekiratli

Reputation: 538

I did not try this but it should give you the output you want.

kubectl get nodes | grep master | awk 'print {$1 $3}'

Upvotes: 0

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