Скачать или смотреть How to Filter Kubernetes Namespaces by Name Using Kubectl

Learn how to use `kubectl` to display only namespace names in Kubernetes, streamlining your bash commands effectively.
---
This video is based on the question https://stackoverflow.com/q/72315850/ asked by the user 'Shritej Murmadkar' ( https://stackoverflow.com/u/17035914/ ) and on the answer https://stackoverflow.com/a/72316389/ provided by the user 'Phani Kumar' ( https://stackoverflow.com/u/19158474/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: Kubectl Namespace script to filter only name

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l...
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Efficiently Filtering Namespace Names in Kubernetes with Kubectl

Kubernetes has become an essential player in the world of container orchestration, allowing developers to manage containers with ease. One common task when dealing with Kubernetes is retrieving information about namespaces. Typically, the command kubectl get namespaces provides a comprehensive overview, but what if you only want the names of the namespaces? In this guide, we will explore how to filter namespace names using a variety of methods in kubectl.

The Problem

When running the command:

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

You receive a detailed output showing namespace names, statuses, and ages like this:

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

While this information is useful, sometimes you only want a clean list of the namespace names. Your expectation is to see an output similar to the following:

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

The Solution

There are several ways to achieve this, depending on your environment and preferences. Below are some effective commands to filter namespace names using kubectl. Feel free to choose the one that suits you best!

Method 1: Using Template

One of the cleanest approaches is to use the --template flag. This command allows you to format the output easily:

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

Breakdown:

--template: Specifies that you're using a go template for formatting the output.

{{range .items}}...{{end}}: This loops over the listed items (namespaces).

{{.metadata.name}}: This extracts the name of each namespace.

{{"\n"}}: Inserts a newline for formatting purposes.

Method 2: Using awk

If you prefer working with awk, this command can help you list only the first column, which contains the namespace names:

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

Breakdown:

This command pipes the output of kubectl to awk, which processes it line-by-line.

{print $1}: This tells awk to print only the first column (the namespace name).

Method 3: Using Custom Columns Option

Another efficient option is to specify custom output columns:

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

Breakdown:

--no-headers: This option suppresses the header row in the output.

-o custom-columns=":metadata.name": This specifies that you want to output custom columns and only the namespace names are selected.

Method 4: Using sed to Clean Output

For users familiar with sed, here's another way to clean the output:

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

Breakdown:

-o=name: This outputs only the namespace's name.

sed "s/^.{10}//": This uses sed to strip out the unnecessary leading characters (which can vary based on your command's setup).

Conclusion

By employing any of these methods, you can streamline your kubectl commands to focus on retrieving just the names of Kubernetes namespaces. This not only simplifies your output but also makes it easier to work with in scripts or automation processes.

Feel free to experiment with these commands and find the one that best fits your workflow. Happy coding!