Skip to main content

Chapter 2.10 - Add-ons and Extensions

Learning Objectives​

By the end of this chapter, you will be able to:

  • Identify essential add-ons
  • Understand CNI plugins
  • Explain cluster extensions
  • Know complementary tools

What is an Add-on?​

Add-ons are optional components that extend Kubernetes functionality. They are not part of the core but are essential for a production cluster.

Essential Add-ons​

1. CNI (Container Network Interface)​

Network plugin to connect Pods:

Popular plugins:

  • Calico: Networking and Network Policies
  • Flannel: Simple overlay network
  • Weave: Networking with encryption
  • Cilium: eBPF-based networking

2. CoreDNS​

DNS service for the cluster:

Features:

  • Internal DNS resolution
  • Service discovery
  • A and SRV records

3. Metrics Server​

Collects resource metrics:

Uses:

  • kubectl top
  • Horizontal Pod Autoscaler
  • Vertical Pod Autoscaler

Optional Add-ons​

Dashboard​

Web interface to manage the cluster:

  • Resource visualization
  • Deployment management
  • Logs and metrics

Ingress Controller​

Manages incoming HTTP/HTTPS traffic:

  • NGINX Ingress: The most popular
  • Traefik: Simple and modern
  • Istio Gateway: For service mesh

Monitoring​

  • Prometheus: Metrics collection
  • Grafana: Visualization
  • Jaeger: Distributed tracing

Summary​

In this chapter, you learned:

Add-ons: Optional but often essential extensions
CNI: Network plugins to connect Pods
CoreDNS: Internal cluster DNS service
Metrics Server: Resource metrics collection
Optional add-ons: Dashboard, Ingress, Monitoring

Next Steps​

Now that you understand add-ons:

Lab 2.2: Analyzing Worker Nodes
Lab 2.3: Monitoring System Components

Chapter created: December 2024