Kubernetes json path

 Use json path to filter data.

#kubectl get nodes

#kubectl get nodes -o wide

1. Identify the kubectl command

2. Familiarize with json output 

#kubectl get nodes -o json

#kubectl get pods -o json

3. Form the json path query

.items[0].spec.containers.[0].image

4. Use the json path query with kubectl command

#kubectl get nodes -o jsonpath='{.items[0].spec.containers.[0].image}'

Combine two query. And separate by {"\n"} or {"\t"}

#kubectl get nodes -o jsonpath='{.items[*].metadata.name}{"\n"}{.items[*].status.capacity.cpu}'

Result:

master node01

4           4

Format the display

Start loop --> '{range .item[*]}

Operation --> {.metadata.name}{"\t"}{.status.capacity.cpu}{"\n"}

End loop --> {end}'

#kubectl get nodes -o jsonpath='{range .item[*]}{.metadata.name}{"\t"}{.status.capacity.cpu}{"\n"}{end}'

Result

master  4

node01 4

Format the display with custom columns

#kubectl get nodes -o custom-columns=<column name>:<json path>

#kubectl get nodes -o custom-columns=NODE:.metadata.name, CPU:.status.capacity.cpu

Result

NODE     CPU

master     4

node01    4

Sort the result

--sort-by=<item>

#kubectl get nodes --sort-by=.metadata.name

#kubectl get pod --sort-by=.status.capacity.cpu

Example: get name, capacity and order by capacity

#kubectl get pv -o custom-columns=NAME:.metadata.name,CAPACITY:.spec.capacity.storage --sort-by=.spec.capacity.storage

Read config file

#kubectl config view --kubeconfig=<config file>

Check config file with condition

kubectl config view --kubeconfig=my-kube-config -o jsonpath="{.contexts[?(@.context.user=='aws-user')].context}"