How can I list the taints on Kubernetes nodes?

Question

The docs are great about explaining how to set a taint on a node, or remove one. And I can use kubectl describe node to get a verbose description of one node, inclu

Answer 1

The simplest way to do this without using any extra tools such as JQ is to use the custom-columns output option.

$ kubectl get nodes -o custom-columns=NAME:.metadata.name,TAINTS:.spec.taints --no-headers 

Output:

master-11   [map[effect:PreferNoSchedule key:node-role.kubernetes.io/master]]
master-12   [map[effect:PreferNoSchedule key:node-role.kubernetes.io/master]]
master-13   [map[effect:PreferNoSchedule key:node-role.kubernetes.io/master]]

With something like Taints where it is a map or list and you want it to look clean for parsing with some other tool you can clean them up using you can use something similar to the answer by Edwin Tai but with a little extra smarts to extract the keys.

kubectl get nodes -o=jsonpath='{range .items[*]}{.metadata.name}{"\t"}{.spec.taints[*].key}{"\n"}{end}' 

Output:

master-11   node-role.kubernetes.io/master
master-12   node-role.kubernetes.io/master
master-13   node-role.kubernetes.io/master
worker-21   thegoldfish.org/storage thegoldfish.org/compute
worker-22   thegoldfish.org/storage thegoldfish.org/compute
worker-23   thegoldfish.org/compute
worker-24   thegoldfish.org/storage thegoldfish.org/compute

Extra examples:

Using this method you can easily create custom outputs

Quick overview of nodes:

kubectl get nodes -o custom-columns=NAME:.metadata.name,ARCH:.status.nodeInfo.architecture,KERNEL:.status.nodeInfo.kernelVersion,KUBLET:.status.nodeInfo.kubeletVersion,CPU:.status.capacity.cpu,RAM:.status.capacity.memory

Output:

NAME        ARCH    KERNEL                       KUBLET    CPU   RAM
master-11   amd64   3.10.0-1062.9.1.el7.x86_64   v1.17.0   6     7910096Ki
master-12   amd64   3.10.0-1062.9.1.el7.x86_64   v1.17.0   6     7910096Ki
master-13   amd64   3.10.0-1062.9.1.el7.x86_64   v1.17.0   6     7910096Ki

Overview of pods and where to find them sorted by creation time:

kubectl get pods -A -o custom-columns=NAMESPACE:.metadata.namespace,NAME:.metadata.name,NODE:.spec.nodeName,HOSTIP:.status.hostIP,PHASE:.status.phase,START_TIME:.metadata.creationTimestamp --sort-by=.metadata.creationTimestamp

Output:

NAMESPACE              NAME                                                  NODE        HOSTIP            PHASE       START_TIME
kube-system            kube-proxy-rhmrz                                      master-11   192.168.121.108   Running     2019-12-26T14:22:03Z
kube-system            coredns-6955765f44-777v9                              master-11   192.168.121.108   Running     2019-12-26T14:22:03Z
kube-system            coredns-6955765f44-w7rch                              master-11   192.168.121.108   Running     2019-12-26T14:22:03Z
kube-system            kube-scheduler-master-11                              master-11   192.168.121.108   Running     2019-12-26T14:22:05Z
kube-system            kube-controller-manager-master-11                     master-11   192.168.121.108   Running     2019-12-26T14:22:05Z
kube-system            etcd-master-11                                        master-11   192.168.121.108   Running     2019-12-26T14:22:05Z
kube-system            kube-apiserver-master-11                              master-11   192.168.121.108   Running     2019-12-26T14:22:05Z
kube-system            calico-node-sxls8                                     master-11   192.168.121.108   Running     2019-12-26T14:55:41Z
kube-system            calico-kube-controllers-6d85fdfbd8-dnpn4              master-11   192.168.121.108   Running     2019-12-26T14:55:41Z
kubernetes-dashboard   dashboard-metrics-scraper-76585494d8-jx9cg            master-11   192.168.121.108   Running     2019-12-26T16:10:16Z
kubernetes-dashboard   kubernetes-dashboard-5996555fd8-5z5p2                 master-11   192.168.121.108   Running     2019-12-26T16:10:16Z

The documentation for this is https://kubernetes.io/docs/reference/kubectl/overview/#custom-columns

Answer 2

kubectl get nodes -o json | jq '.items[].spec'

which will give the complete spec with node name, or:

kubectl get nodes -o json | jq '.items[].spec.taints'

will produce the list of the taints per each node

Answer 3

I was looking to get the list of nodes that have a specific Taint. I only found this SO answer, so if anybody is looking for this answer, here is the solution:

kubectl get nodes -o go-template='{{range $item := .items}}{{with $nodename := $item.metadata.name}}{{range $taint := $item.spec.taints}}{{if and (eq $taint.key "node-role.kubernetes.io/master") (eq $taint.effect "NoSchedule")}}{{printf "%s\n" $nodename}}{{end}}{{end}}{{end}}{{end}}'

On my cluster, the output is:

preprod-master
preprod-proxy

Answer 4

PowerShell:\> kubectl describe nodes | findstr "Taint Hostname"

or

Bash# kubectl describe nodes | egrep -hi "Taint|Hostname"

This command is mad easy to remember

Output looks like this:

Taints:             <none>  
  Hostname:   aks-agentpool-30208295-0  
Taints:             <none>    
  Hostname:  aks-agentpool-30208295-1
...

Answer 5

kubectl describe nodes [node_name] | grep 'Taints'

kubectl get nodes -o json | jq '.items[].spec.taints' 

--> this last step will require jq installed ( sudo apt install jq)