K9s: Terminal UI for Kubernetes

K9s is a powerful terminal-based UI for interacting with Kubernetes clusters. It provides an intuitive interface to navigate, observe, and manage your applications and resources.

Why Use K9s?

K9s offers several advantages over traditional kubectl commands:

1. Real-time Monitoring: Live updates of cluster resources
2. Intuitive Navigation: Easy keyboard shortcuts and commands
3. Resource Management: Quick access to logs, shell, and resource editing
4. Cluster Context Switching: Seamless switching between multiple clusters
5. Resource Filtering: Powerful search and filtering capabilities
6. Plugin System: Extensible with custom plugins
7. Resource Metrics: CPU/Memory usage visualization

Installation

Using Package Managers

Debian/UbuntuRedHat/FedoraArch Linux

# Using apt (Recommended)
curl -fsSL https://pkgs.k9s.dev/key.gpg | sudo gpg --dearmor -o /usr/share/keyrings/k9s-archive-keyring.gpg
echo "deb [signed-by=/usr/share/keyrings/k9s-archive-keyring.gpg] https://pkgs.k9s.dev/deb stable main" | sudo tee /etc/apt/sources.list.d/k9s.list
sudo apt update
sudo apt install k9s

# Using snap
sudo snap install k9s

# Using dnf
sudo dnf config-manager --add-repo https://pkgs.k9s.dev/rpm/k9s.repo
sudo dnf install k9s

# Alternative: Direct RPM installation
VERSION=$(curl -s https://api.github.com/repos/derailed/k9s/releases/latest | grep tag_name | cut -d '"' -f 4)
curl -LO https://github.com/derailed/k9s/releases/download/${VERSION}/k9s_Linux_amd64.rpm
sudo rpm -ivh k9s_Linux_amd64.rpm

# Using pacman
sudo pacman -S k9s

# Using yay (AUR)
yay -S k9s-bin

Using Binary Release

# Download latest binary
VERSION=$(curl -s https://api.github.com/repos/derailed/k9s/releases/latest | grep tag_name | cut -d '"' -f 4)
curl -LO https://github.com/derailed/k9s/releases/download/${VERSION}/k9s_Linux_amd64.tar.gz

# Extract and install
tar xzf k9s_Linux_amd64.tar.gz
sudo install -o root -g root -m 0755 k9s /usr/local/bin/k9s

# Verify installation
k9s version

Using Container Image

# Run using Docker
docker run --rm -it -v ~/.kube/config:/root/.kube/config ghcr.io/derailed/k9s

# Run using Podman
podman run --rm -it -v ~/.kube/config:/root/.kube/config ghcr.io/derailed/k9s

Installation Best Practices

• Always verify GPG keys and signatures when installing via package managers
• Keep K9s updated to benefit from the latest features and security fixes
• Consider using the container image in restricted environments
• Back up your K9s configuration before upgrading

Basic Usage

Starting K9s

# Start with default context
k9s

# Start with specific context
k9s --context my-cluster

# Start in a specific namespace
k9s -n kube-system

Key Features and Commands

Navigation

• 0-9: Switch to namespace
• :: Enter command mode
• /: Enter filter mode
• esc: Go back/Clear filter
• ctrl-a: Show all resources
• ctrl-d: Delete resource
• ctrl-k: Kill pod
• ?: Show help

Resource Views

# Access different resources using commands
:pods          # View pods
:deployments   # View deployments
:services      # View services
:nodes         # View nodes
:configmaps    # View configmaps
:secrets       # View secrets

Pod Management

# While in pod view
l              # View logs
s              # Shell into container
d              # Describe pod
e              # Edit pod
y              # YAML view
ctrl-k         # Kill pod

Cluster Context Management

# Switch contexts
:context       # List available contexts
ctrl-c         # Open context switch menu

Multi-Cluster Configuration

Using Different Kubeconfig Files

1. Default Configuration:

   # K9s uses default kubeconfig at ~/.kube/config
   k9s
   

2. Specific Kubeconfig:

   # Use a specific kubeconfig file
   k9s --kubeconfig=/path/to/kubeconfig
   
   # Set environment variable
   export KUBECONFIG=/path/to/kubeconfig
   k9s
   

3. Multiple Kubeconfig Files:

   # Merge multiple kubeconfig files
   export KUBECONFIG=~/.kube/config-cluster1:~/.kube/config-cluster2
   k9s
   

Creating Cluster-Specific Aliases

# Add to your ~/.bashrc or ~/.zshrc
alias k9s-prod="k9s --kubeconfig=/path/to/prod-kubeconfig"
alias k9s-dev="k9s --kubeconfig=/path/to/dev-kubeconfig"
alias k9s-staging="k9s --kubeconfig=/path/to/staging-kubeconfig"

Customization

Configuration File

K9s uses a configuration file located at ~/.k9s/config.yml:

k9s:
  refreshRate: 2
  maxConnRetry: 5
  enableMouse: false
  headless: false
  logoless: false
  crumbsless: false
  readOnly: false
  noIcons: false
  logger:
    tail: 100
    buffer: 5000
    sinceSeconds: 60
    fullScreenLogs: false
    textWrap: false
    showTime: false
  currentContext: minikube
  currentCluster: minikube
  clusters:
    minikube:
      namespace:
        active: default
        favorites:
        - default
        - kube-system
      view:
        active: pods
      featureGates:
        nodeShell: false
      shellPod:
        image: busybox:1.31
        command: []
        args: []
        namespace: default

Skin Customization

Create a custom skin at ~/.k9s/skin.yml:

k9s:
  body:
    fgColor: dodgerblue
    bgColor: black
    logoColor: orange
  prompt:
    fgColor: cadetblue
    bgColor: black
    suggestColor: dodgerblue
  info:
    fgColor: orange
    sectionColor: white

Best Practices

1. Resource Organization

• Use namespaces as logical groupings for resources
• Create custom resource views for different workflows
• Utilize labels and filters for efficient resource management
• Set up port-forwarding for frequently accessed services

2. Performance Optimization

• Increase refresh rate in large clusters (>1000 pods)
• Filter by namespace when working in specific areas
• Use readonly mode for monitoring to reduce API calls
• Limit resource views to relevant namespaces

3. Security Considerations

• Maintain separate kubeconfig files for each environment
• Enable readonly mode for audit and review tasks
• Follow the principle of least privilege with RBAC
• Regularly rotate cluster credentials
• Use context-specific configurations

4. Workflow Efficiency

• Master essential keyboard shortcuts (:, /, ctrl+a)
• Configure custom skins for better visibility
• Set up command aliases for common operations
• Use hotkeys for frequent namespace switches
• Configure persistent views for regular tasks

5. Cluster Management

• Monitor resource utilization with built-in metrics
• Set up custom resource views for different roles
• Use benchmarks for performance monitoring
• Configure alerts for critical resources

6. Troubleshooting

• Enable logging for debugging sessions
• Use describe and events for detailed resource info
• Set up custom views for error tracking
• Configure proper log buffer sizes

Troubleshooting

Common Issues

1. Connection Problems:

   # Check kubeconfig
   k9s info
   
   # Verify cluster access
   kubectl cluster-info
   

2. Performance Issues:

   # Adjust refresh rate in ~/.k9s/config.yml
   k9s:
     refreshRate: 5  # Increase refresh interval
   

3. Resource Access:

   # Check RBAC permissions
   kubectl auth can-i --list
   

Additional Resources

• Official K9s Documentation
• GitHub Repository
• K9s Release Notes
• K9s Plugins