K9s – CLI Management Advanced Usage

Introduction

K9s for advanced usage, exploring, technical examples for experienced Kubernetes users.\
provide by target-ops

Install K9s using Homebrew:

brew install k9s 

Alternatively, download the latest binary from the K9s releases page and add it to your PATH.

1. Custom Resource Views

K9s allows you to create custom views for specific Kubernetes resources.\
Create a $HOME/.k9s/views.yml file:

k9s: views: v1/pods: columns: - NAME - READY - STATUS - RESTARTS - CPU - MEM - AGE - NODE 

This configuration customizes the pod view to include CPU and memory usage.

2. Plugins

K9s supports plugins for extended functionality. Create a plugin in $HOME/.k9s/plugins.yml:

plugins: helm: shortCut: Ctrl-H description: Helm Charts scopes: - all command: kubectl background: false args: - get - helmreleases - --all-namespaces 

This plugin allows quick access to Helm releases across all namespaces.

3. Resource Editing

built-in YAML editor for resources. To edit a resource:

1. Navigate to the resource
2. Press e to open the editor
3. Make changes and save

4. Port Forwarding

Easily set up port forwarding:

1. Navigate to a pod
2. Press Shift-F
3. Enter local and remote ports

Example:
CopyLocal Port: 8080
Remote Port: 80 

This forwards local port 8080 to the pod’s port 80.

5. Log Streaming and Filtering

Stream logs from multiple pods simultaneously:

1. Select pods using the space bar

2. Press l to view logs Apply filters using the / key:

   error|warning

This filters logs to show only lines containing “error” or “warning”.

7. CRD Management

Easily manage Custom Resource Definitions (CRDs):

1. Press :crd to list all CRDs
2. Navigate to a CRD and press enter to view instances

8. Context and Namespace Switching

Quickly switch between contexts and namespaces:

Press :ctx to list contexts Press :ns to list namespaces

9. Cluster Events Monitoring

Monitor cluster-wide events:

1. Press :events or ctrl-e
2. View real-time cluster events

Filter events: /NodeNotReady|FailedMount

10. Resource Utilization

View resource utilization across the cluster:

1. Press :pulses or ctrl-u
2. Monitor CPU, memory, and storage usage

11. YAML Diff

Compare resource YAML definitions:

1. Navigate to a resource
2. Press d to view YAML diff
3. Use j and k to navigate changes

This is useful for tracking changes over time or across environments.

Advanced Example: Automated Deployment Analysis

Let’s create a K9s plugin that analyzes deployments and reports potential issues.

1. Create a script analyze_deployments.sh:

#!/bin/bash kubectl get deployments -A -o json | jq -r ' .items[] | select(.spec.replicas != .status.availableReplicas) | "\(.metadata.namespace),\(.metadata.name),\(.spec.replicas),\(.status.availableReplicas)" ' | column -t -s, -N "Namespace,Deployment,Desired,Available" 

1. Add the plugin to $HOME/.k9s/plugins.yml:

plugins: analyze-deployments: shortCut: Ctrl-A description: Analyze Deployments scopes: - deployments command: /path/to/analyze_deployments.sh background: false 

1. In K9s, press Ctrl-A to run the analysis

This plugin quickly identifies deployments where the desired state doesn’t match the current state, helping troubleshoot scaling or health issues. Conclusion.

K9s offers a wealth of advanced features for managing Kubernetes clusters on macOS. By leveraging custom views, plugins, and built-in tools, you can significantly enhance your Kubernetes workflow. Experiment with these advanced techniques to streamline your cluster management and gain deeper insights into your Kubernetes environments.