docker-kuber

https://jsonpathfinder.com/

1. Which kubernetes context:

   kubectl config current-context kubectl get nodes -o wide
   kubectl describe node | more

List of containers inside a pod:

> kubectl get pods [pod-name-here] -n [namespace] -o jsonpath='{.spec.containers[*].name}'

kubectl filter and output control ( inbuilt GOLANG Templates )

kubectl get no -o go-template='{{range .items}}{{if .spec.unschedulable}}{{.metadata.name}} {{.spec.externalID}}{{"\n"}}{{end}}{{end}}'
or
kubectl get no -o go-template="{{range .items}}{{if .spec.unschedulable}}{{.metadata.name}} {{.spec.externalID}}:{{end}}{{end}}" | tr ":" "\n"

author - could not find an easy way to print newline characters with inline golang template, so used a trick printing colons and using tr to convert colons to newlines.

RANGE to iterate

Kubectl supports a superset of JSONPath, with a special range keyword to iterate over ranges, using the same trick to add newlines:

kubectl get no -o jsonpath="{range.items[?(@.spec.unschedulable)]}{.metadata.name}:{end}" | tr ":" "\n"

Print Custom Columns

Print custom columns [Node]

kubectl get no -A -o=custom-columns=NAME:.metadata.name,CPU:.status.allocatable.cpu

Service :

kubectl get svc -A -o=custom-columns=Pod-Name:.metadata.name,Cluster-IP:spec.clusterIP

Search with jsonpath and print chosen column for search result

Search Criteria :
items[].metadata.name=="kube-dns"

Field to retrieve value for matching search :
items[].spec.clusterIP

kubectl get svc -n kube-system -o=jsonpath='{.items[?(@.metadata.name=="kube-dns")].spec.clusterIP}'

Display pods by age in ascending order

kubectl get pods --sort-by={metadata.creationTimestamp}