Kubernetes Crash Course by Nana

Introduction

• Host: Nana
• Purpose: Teach Kubernetes basics in one hour
• Taught via: YouTube channel, online courses, DevOps educational program
• Agenda:
  1. What is Kubernetes and its importance
  2. Kubernetes architecture overview
  3. Main Kubernetes components
  4. Hands-on demo project

What is Kubernetes?

• Definition: Open-source container orchestration framework developed by Google
• Manages applications made up of hundreds/thousands of containers
• Environments: Physical machines, virtual machines, cloud, hybrid

Why Kubernetes?

• Context: Rise of microservices -> container usage
• Challenges: Managing many containers across multiple environments is complex
• Needs: Container orchestration tools required for:
  • High availability: No downtime
  • Scalability: Fast scaling up/down based on load
  • Disaster recovery: Backup and restore capabilities

Kubernetes Architecture

• Cluster Components: Master Node and Worker Nodes
• Master Node:
  • API Server: Main entry point for Kubernetes clients (UI, API, CLI)
  • Controller Manager: Handles cluster state and repairs
  • Scheduler: Allocates containers to nodes based on resources and load
  • etcd: Key-value storage holding the cluster state
  • Virtual Network: Enables node communication
• Worker Nodes:
  • kubelet: Kubernetes process on each node enabling communication
  • Containers: Run the application workload
  • Resources: Typically larger than master node
• Production: Multiple master nodes for redundancy

Core Kubernetes Components

• Pod: Smallest unit; abstraction over a container
  • Runs one application container
• Service: Static IP for Pod communication; internal and external types
• Ingress: Forwards external requests to services
• ConfigMap: Stores external configuration data
• Secret: Stores sensitive information like passwords, certificates
• Volume: Attaches physical storage to a pod for data persistence
• Deployment: Manages and scales application pods
• StatefulSet: Manages stateful applications like databases

Kubernetes Configuration

• Configuration files in YAML or JSON format
• API Server: Main entry for configuration requests
• Example Components: Deployment and Service
• YAML file structure:
  1. Metadata
  2. Specification
  3. Status (auto-generated)
• Deployment YAML:
  • Defines replicas, pod template
  • Pod template contains container image, environment variables
• Service YAML:
  • Defines selector to match pods
  • Ports for service and target

Tools and Setup

• Minikube: Local Kubernetes cluster with both master and worker processes
  • Install: Various OS, requires Docker as a driver
  • Start: minikube start --driver=docker
  • Status: minikube status
• kubectl: CLI for interacting with Kubernetes clusters
  • Common commands: kubectl get, kubectl describe, kubectl logs

Hands-On Project

• Setup: Visual Studio Code
• Components to deploy:
  1. ConfigMap for MongoDB URL
  2. Secret for MongoDB credentials
  3. Deployment and service for MongoDB
  4. Deployment and service for a web application
• Example Commands:
  • Create ConfigMap: kubectl apply -f config.yaml
  • Create Secret: kubectl apply -f secret.yaml
  • Deploy MongoDB: kubectl apply -f mongo.yaml
  • Deploy Web App: kubectl apply -f webapp.yaml
• Accessing Application: minikube ip + NodePort