====== Cluster Model ======

A Kubernetes cluster is a group of machines that work together to run applications.

It is made of:
  * Control Plane (brain)
  * Worker Nodes (workers)
  * Pods (applications)

---

===== 1. Control Plane =====

The Control Plane is the **brain of Kubernetes**.

It decides:
  * Where applications run
  * How many copies run
  * What happens when something fails

Example:
  * You say: "Run 3 replicas of my app"
  * Control Plane ensures it happens

---

===== 2. Worker Nodes =====

Worker Nodes are machines that **run your applications**.

Example:


Node A → runs Pod 1, Pod 2
Node B → runs Pod 3


If a node fails:
  * Kubernetes moves Pods to another node

---

===== 3. Pods =====

A Pod is the **smallest unit in Kubernetes**.

Example:

A Pod contains:
  * Your application container (e.g. nginx)
  * Optional helper containers

Example:


Pod = Web App Container


---

===== Full flow example =====

User request flow:


User
↓
Service
↓
Pod
↓
Node


Control Plane ensures:
  * Pods are created
  * Pods are healthy
  * Pods are distributed across nodes

---

===== Simple analogy =====

Think of a factory:

  * Control Plane → factory manager
  * Worker Nodes → machines
  * Pods → products being produced