Introduction

This article provides an introduction to Kubernetes, a popular container orchestration platform known as k8s, which simplifies deploying, scaling, and managing containerized applications. It highlights the prerequisites of Docker knowledge and the utility of Kubernetes for auto-healing, autoscaling, and system observation. Key concepts include nodes, clusters, images, containers, and pods. The article also offers practical guidance on creating Kubernetes clusters using tools like Kind and Minikube, both locally and on cloud platforms such as GKE and AWS K8s.

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What is kubernetes

Docker is a pre-requisite before you proceed to understand kubernetes

Kubernetes (popularly known as k8s) is a container orchestration engine, which as the name suggests lets you create, delete, and update containers

This is useful when

1. You have your docker images in the docker registry and want to deploy it in a cloud native fashion

2. You want to not worry about patching, crashes. You want the system to auto heal

3. You want to autoscale with some simple constructs

4. You want to observe your complete system in a simple dashboard

💡

Kubernetes is also known as k8s. K_ _ s

Before kubernetes

Backend

Frontend (Nextjs)

Frontend (React)

After kubernetes

Your frontend, backend are all pods in your kubernetes cluster

Jargon

Ref - https://kubernetes.io/docs/concepts/overview/components/

Nodes

In kubernetes, you can create and connect various machines together, all of which are running kubernetes. Every machine here is known as a node

There are two types of nodes

Master Node (Control pane) - The node that takes care of deploying the containers/healing them/listening to the developer to understand what to deploy

![notion image](https://www.notion.so/image/https%3A%2F%2Fprod-files-secure.s3.us-west-2.amazonaws.com%2F085e8ad8-528e-47d7-8922-a23dc4016453%2Fbc046171-9624-411b-a06b-391ac9d38af8%2FScreenshot_2024-06-01_at_2.55.57_AM.png?table=block&id=28f4ee90-9008-4054-a9ea-427e218272dd&cache=v2 align="left")

Worker Nodes - The nodes that actually run your Backend/frontend

![notion image](https://www.notion.so/image/https%3A%2F%2Fprod-files-secure.s3.us-west-2.amazonaws.com%2F085e8ad8-528e-47d7-8922-a23dc4016453%2F2f0cf057-07cf-43d7-8865-d56f84ac664d%2FScreenshot_2024-06-01_at_3.19.30_AM.png?table=block&id=fb76030e-0923-45af-b81f-d9bba531f3d3&cache=v2 align="left")

Cluster

A bunch of worker nodes + master nodes make up your kubernetes cluster . You can always add more / remove nodes from a cluster.

Images

A Docker image is a lightweight, standalone, and executable software package that includes everything needed to run a piece of software, including the code, runtime, libraries, environment variables, and configuration files. Images are built from a set of instructions defined in a file called a Dockerfile.

Eg - https://hub.docker.com/_/mongo

Containers

A container is an image in execution. For example if you run

docker run -p 5432:5432 -e POSTGRES_PASSWORD=mysecretpassword  -d postgres

Pods

A pod is the smallest and simplest unit in the Kubernetes object model that you can create or deploy

Creating a k8s cluster

Locally (Make sure you have docker)

1. minukube

2. kind - https://kind.sigs.k8s.io/docs/user/quick-start/

On cloud

1. GKE

2. AWS K8s

3. vultr

Using kind

• Install kind - https://kind.sigs.k8s.io/docs/user/quick-start/#installation

Single node setup

• Create a 1 node cluster

kind create cluster --name local

• Check the docker containers you have running

docker ps

• You will notice a single container running (control-pane)

• Delete the cluster

kind delete cluster -n local

Multi node setup

• Create a clusters.yml file

kind: Cluster
apiVersion: kind.x-k8s.io/v1alpha4
nodes:
- role: control-plane
- role: worker
- role: worker

• Create the node setup

 kind create cluster --config clusters.yml --name local

• Check docker containers

docker ps

Now you have a node cluster running locally

Using minikube

• Install minikube - https://minikube.sigs.k8s.io/docs/start/?arch=%2Fmacos%2Fx86-64%2Fstable%2Fbinary+download

• Start a k8s cluster locally

minikube start

• Run docker ps to see the single node setup

💡

A single node setup works but is not ideal. You don’t want your control pane to run containers/act as a worker.