Скачать или смотреть Display Kubernetes Resources from Specific Namespaces Using the kubectl CLI

Learn how to use `kubectl` with go-template to display resources from specific Kubernetes `namespaces` efficiently.
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Displaying Kubernetes Resources from Specific Namespaces Using the kubectl CLI

Kubernetes (K8s) is a powerful container orchestration platform that manages deployments seamlessly. One common task for K8s users is displaying resources from particular namespaces in their cluster using the command-line interface (CLI) tool, kubectl.

The Problem

Many users often find themselves needing to retrieve information about resources (like pods, services, etc.) from specific namespaces. When given multiple namespaces, one might wonder:

Is it possible to display Kubernetes resources from multiple specified namespaces using only the CLI (kubectl)?

While the --all-namespaces flag allows users to view resources across the entire cluster, it becomes tricky when users want to filter the output to only show resources from selected namespaces, especially since flags like --field-selector or --selector don’t support the desired filtering for multiple namespaces.

The Solution: Using go-template

The good news is that you can indeed achieve this by utilizing the go-template output option available with kubectl. Below, I'll walk you through how to effectively use go-template to print the names of the pods from specific namespaces.

Step-by-Step Guide

Identify Your Namespaces:

Let’s assume we have two namespaces: test-1 and test-2.

Use the kubectl get Command:

Here’s how you would construct your command:

[[See Video to Reveal this Text or Code Snippet]]

Breaking Down the Command

kubectl get pod -A:

This tells kubectl to get all pods across all namespaces.

-o go-template:

This option allows you to format the output using Go templating, providing you a flexible way to filter and display your data.

The core of the go-template syntax:

{{range .items}}: Iterate through the list of items (pods).

{{if or (eq .metadata.namespace "test-1") (eq .metadata.namespace "test-2") }}: This condition checks if the pod's namespace is either test-1 or test-2.

{{printf "%s %s\n" .metadata.namespace .metadata.name}}: This formats and prints the namespace and name of the pod.

{{end}}: This ends the block, effectively closing the loop.

Example Output

When you run the command after replacing the namespaces with your actual ones, it will yield output resembling the following:

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

Being able to filter and display Kubernetes resources from specific namespaces using the kubectl CLI is incredibly useful for managing and monitoring your K8s environment. The go-template functionality not only facilitates this task but also empowers users to customize their output to fit their specific needs.

The next time you need to filter resources by namespaces in Kubernetes, remember this handy command with go-template!

Keep experimenting with different outputs and get the most out of your Kubernetes management strategy!