Kubernetes In Action

Diving Into Kubernetes: From

Nodes To Pods

Learning Outcome

Earlier we have seen

What Docker is

How containers package applications

Basic Docker commands

How Docker images and containers work

How containerization solves environment issues

Now we will learn how Kubernetes manages and orchestrates containers at scale

Understanding the Concept

What is Kubernetes?

Kubernetes is often called: Container Orchestration Platform

Because it orchestrates (manages and coordinates)

containers across infrastructure

Kubernetes works with container tools like Docker

History of Kubernetes

Kubernetes was originally developed by Google.

Background:

• Google had massive infrastructure

• They were running billions of containers

• They created an internal system called Borg

Borg helped Google:

• Schedule containers

• Manage workloads

• Scale applications

In 2014, Google released Kubernetes as an open-source project.

The project is now maintained by the
Cloud Native Computing Foundation (CNCF).

Many companies contribute to Kubernetes today.

It has become the industry standard for container orchestration.

Why Kubernetes is Needed

Running containers with Docker is easy.

But problems arise when we run hundreds or thousands of containers.

Challenges:

• Managing many containers manually

• Handling container failures

• Scaling applications

• Load balancing traffic

• Updating applications without downtime

Core Concepts (.....Slide N-3)

Example problem:

A web application needs:

• 10 containers today

• 200 containers during high traffic

Manually managing this is very difficult.

 Kubernetes solves this by automating container management.

What is a Kubernetes Cluster?

A Kubernetes Cluster is a group of machines that run containerized applications.

These machines are called Nodes.

A cluster contains two main components:

1️⃣ Control Plane (Master Node)
2️⃣ Worker Nodes

Structure:

Control Plane
⬇
Manages the Cluster
⬇
Worker Nodes
⬇
Run Applications (Pods)

Clusters allow applications to run across multiple machines for reliability and scalability.

Kubernetes Architecture Overview

Kubernetes architecture consists of two major parts:

1. Control Plane

Responsible for managing the cluster.

It makes decisions such as:

• Scheduling containers

• Monitoring cluster health

• Managing workloads

2. Worker Nodes

Worker nodes run the actual applications.

They contain containers grouped into Pods.

Architecture Flow:

User Request
⬇
Kubernetes Control Plane
⬇
Worker Nodes
⬇
Pods Running Containers

Kubernetes Control Plane 

The Control Plane is responsible for managing the Kubernetes cluster.

It controls the entire system.

Main responsibilities:

• Scheduling workloads

• Maintaining desired cluster state

• Monitoring nodes and containers

• Managing cluster communication

Major Control Plane Components

API Server

• Entry point for Kubernetes commands

Scheduler

• Decides which node runs a pod

Controller Manager

• Ensures cluster state remains correct

etcd

• Distributed database storing cluster data

The Control Plane acts as the brain of the Kubernetes cluster.

 Worker Node

A Worker Node is a machine that runs the application containers.

Each worker node contains:

• Container runtime

• Kubernetes agent

• Pods running applications

Main components inside Worker Node:

Kubelet

Agent that communicates with the control plane and manages containers.

Container Runtime

Runs containers (Docker, containerd, etc.)

Kube Proxy

Handles network communication between services and pods.

Worker nodes execute the tasks assigned by the control plane.

What is a Node?

A Node is a physical or virtual machine in the Kubernetes cluster.

Nodes provide the computing resources needed to run containers

Types of Nodes:

Control Plane Node

• Manages cluster operations

Worker Node

• Runs application workloads

Each node includes:

• CPU

• Memory

• Storage

• Network resources

Nodes allow Kubernetes to distribute workloads efficiently.

What is a Pod?

A Pod is the smallest deployable unit in Kubernetes.

Pods contain one or more containers.

Containers in the same pod:

• Share network

• Share storage

• Work together as a single unit

Core Concepts (.....Slide N-3)

Example:

A pod might include:

• Web server container

• Logging container

Pods are temporary and can be recreated automatically if they fail.

Kubernetes manages pods rather than individual containers.

Kubernetes Features

Kubernetes provides powerful features for managing containers.

Automatic Scaling

Applications can scale up or down based on demand.

Self-Healing

If a container fails, Kubernetes automatically:

• Restarts it

• Replaces it

• Moves it to another node if needed

Load Balancing

Traffic is automatically distributed across containers.

Automated Deployment

Applications can be deployed and updated without downtime.

Resource Optimization

Efficient use of CPU and memory across the cluster.

Kubernetes Workflow

Typical Kubernetes workflow:

Developer creates Container Image

⬇

Image stored in Container Registry

⬇

Developer writes Kubernetes configuration (YAML)

⬇

Kubernetes creates Pods

⬇

Pods run on Worker Nodes

⬇

Control Plane continuously monitors system

If a pod fails → Kubernetes automatically recreates it.

Summary

Which of the following is the smallest deployable unit in Kubernetes?

Which of the following is the smallest deployable unit in Kubernetes?