Quick Guide to Kubernetes

Kubernetes is a container orchestration system. It helps you deploy, scale, manage, and heal your containerized applications (like Docker containers) automatically.

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⚙️ High-Level Architecture:

+------------------+
|     User (You)   |
+--------+---------+
         |
         v
+--------+----------+        +----------------+
|   Kubernetes API  | <----> |     kubectl    |
|     (Control Plane)|       +----------------+
+--------+----------+
         |
         v
+--------+----------+---------------------------+
| Scheduler | Controller Manager | etcd (DB)    |
+-----------+--------------------+--------------+
         |
         v
+--------+----------+
|     Kubelet       |     <--- On each worker node
|   (runs on nodes) |
+--------+----------+
         |
         v
+------------------+
|   Container Runtime (Docker/containerd)       |
|   Runs Pods with app containers inside        |
+------------------+

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🔁 How It Works (Step by Step Flow):

1. You define YAML

You write a YAML file describing a:

• Deployment

• Service

• Ingress

• ConfigMap, etc.

2. You apply with kubectl apply -f

This talks to the Kubernetes API Server.

3. Control Plane stores the config

The API Server saves it in etcd (a key-value store).

4. Scheduler picks a Node

The Scheduler finds the best Node to run the Pod.

5. Kubelet starts the Pod

The selected Node's kubelet:

• Pulls the container image

• Starts the container

• Monitors its health

6. Kube-proxy manages network

Handles service discovery, routing, load balancing between Pods.

7. Ingress (optional)

Ingress Controller handles HTTP/HTTPS and routes traffic to Services.

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📦 Key Components You Use

Component	Role
Pod	Smallest unit — runs 1 or more containers
Deployment	Manages Pod replicas (scaling, self-healing)
Service	Exposes Pods (ClusterIP, NodePort, LoadBalancer)
Ingress	Routes external HTTP(S) to Services
ConfigMap/Secret	Injects configs or secrets into Pods
Namespace	Isolates groups of resources