Kubectl Filtering Masterclass

Stop scrolling through 500 lines of YAML. The CKA requires you to answer specific data questions like "Which nodes have taints?" or "What image is the kube-scheduler using?" instantly.

1. JSONPath: The Scalpel

The -o jsonpath flag is your surgical tool.

Syntax: kubectl get [resource] -o jsonpath='{.path.to.field}'

Recipe: Get Internal IP of all Nodes

kubectl get nodes -o jsonpath='{.items[*].status.addresses[?(@.type=="InternalIP")].address}'

Recipe: Get Pod Name & Image List

kubectl get pods -A -o jsonpath='{range .items[*]}{.metadata.name}{"\t"}{.spec.containers[*].image}{"\n"}{end}'

2. Custom Columns: The Report Generator

Easier than JSONPath for simple tables.

Recipe: Scheduling Audit Table Shows Pod Name, Node Name, and QOS Class.

kubectl get pods -A -o custom-columns=NAME:.metadata.name,NODE:.spec.nodeName,QOS:.status.qosClass

3. Sorting (--sort-by)

Kubernetes can sort output based on any field.

Recipe: Find the Oldest Pod

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

Recipe: Find the Pod Restarting the Most (Note: This requires scripting as restartCount is inside the container status list, but simple sorting works well for top-level fields).

4. The "No-Headers" Trick

When you need to count things. kubectl get pods --no-headers | wc -l