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Chapter 2.1 - Architecture Overview

Learning Objectives​

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

  • Understand the separation between Control Plane and Worker Nodes
  • Identify the responsibilities of each component
  • Visualize the communication flows
  • Understand high availability concepts

Layered Architecture​

Kubernetes follows a well-defined layered architecture:

Control Plane vs Worker Nodes​

Control Plane (Master)​

Role: Make decisions and maintain the desired state

Characteristics:

  • Can be replicated for high availability
  • Generally does not run user workloads
  • Consumes CPU and memory resources
  • Communicates with all Worker Nodes

Worker Nodes​

Role: Run the applications

Characteristics:

  • Can be added/removed dynamically
  • Runs the Pods (applications)
  • Communicates with the Control Plane
  • Can be in different datacenters/clouds

Communication Flows​

1. User -> API Server​

2. API Server -> Scheduler -> kubelet​

3. Controller Manager -> API Server​

High Availability​

For production, the Control Plane must be highly available:

Advantages:

  • Fault tolerance
  • No single point of failure
  • Horizontal scalability

Summary​

In this chapter, you learned:

Layered architecture: Application -> Orchestration -> Infrastructure
Control Plane: Makes decisions, maintains state
Worker Nodes: Run the applications
Communication: Well-defined flows between components
High Availability: Control Plane replication for production

Next Steps​

Now that you understand the overall architecture:

Chapter 2.2: API Server - The Entry Point
Chapter 2.3: etcd - The Database

Chapter created: December 2024