Umang Pincha's Blog

Namaste Kubernetes 🙏🏻 (Part 1)

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Umang Pincha
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Table of contents

In this series of Namaste Kubernetes(k8s) we are going to learn bredth & width of k8s.

Pre-requisite:

Linux , Docker

Before even learning Kubernetres or any topic in this entire world we must be clear with these 3 questions

  1. What ?

  2. Why ?

  3. How ?

Q. What is Kubernetes ?

Ans. Kubernetes or K8s is an orchestration tool to manage containers , In simple words it manages containers if they are died or if any abnormality happens to them. like heal , auto-repair or auto-scale.

Q. Why we have to learn Kubernetes ?

Ans. To manage our applications , customers more effectively so that they dont face any downtime.

Q. How ?

Ans: For this we have to see its architecture.

Let’s learn k8s Architecture

In k8s cluster we bascially have 2 parts

  1. Master (control plane)

  2. Worker

Think it like an MNC where lots of people are working

Master

Its consist of 5 components

  1. etcd : Database to store information.

  2. scheduler : It like an HR which do the job given by team lead (here lead is api-server).

  3. controller manager: Its like a manager who will see if everyone is working properly in an organization.

  4. api-server: Its like a team lead who assign the task to scheduler (HR)

Worker

Its consist of 2 components

  1. Kubelet

  2. Server-Proxy

Kubelet

It continously sees if the pods are working properly or not , if not it will report it to api-server.

Server-Proxy

It helps user to interact with cluster

How can we forget CEO ? 😛

Kubectl

This person is the CEO of company and instruct api-server directly.

Let’s install k8s via kind

What is kind ?

kind is a tool for running local Kubernetes clusters using Docker container “nodes”.
kind was primarily designed for testing Kubernetes itself, but may be used for local development or CI.

Install docker in ubuntu

sudo apt update
sudo apt-get install docker.io

Install kind

# For AMD64 / x86_64
[ $(uname -m) = x86_64 ] && curl -Lo ./kind https://kind.sigs.k8s.io/dl/v0.25.0/kind-linux-amd64
# For ARM64
[ $(uname -m) = aarch64 ] && curl -Lo ./kind https://kind.sigs.k8s.io/dl/v0.25.0/kind-linux-arm64
chmod +x ./kind
sudo mv ./kind /usr/local/bin/kind

Install kubectl

Follow documentation : link

  1. Download the latest release with the command:
curl -LO "https://dl.k8s.io/release/$(curl -L -s https://dl.k8s.io/release/stable.txt)/bin/linux/amd64/kubectl"
  1. Validate the binary (optional)
curl -LO "https://dl.k8s.io/release/$(curl -L -s https://dl.k8s.io/release/stable.txt)/bin/linux/amd64/kubectl.sha256"
  1. Validate the kubectl binary against the checksum file:
echo "$(cat kubectl.sha256)  kubectl" | sha256sum --check
# If valid, the output is:
# kubectl: OK
  1. Install kubectl
sudo install -o root -g root -m 0755 kubectl /usr/local/bin/kubectl
  1. Test to ensure the version you installed is up-to-date:
kubectl version --client

Remember : Everything in k8s is a manifest file

config.yaml

kind: Cluster
apiVersion: kind.x-k8s.io/v1alpha4
name: umang-cluster

nodes:
- role: control-plane
  image: kindest/node:v1.31.2
- role: worker
  image: kindest/node:v1.31.2
- role: worker
  image: kindest/node:v1.31.2

Lets see the above yml file

Kind : Type of File

apiVersion: Its the api version

name : cluster name

nodes : give information regarding how many nodes are running

The above manifest file will create 1 master and 2 worker nodes

Command to create cluster

$ kind create cluster --config=config.yaml
Creating cluster "umang-cluster" ...
 ✓ Ensuring node image (kindest/node:v1.31.2) 🖼
 ✓ Preparing nodes 📦 📦 📦  
 ✓ Writing configuration 📜 
 ✓ Starting control-plane 🕹️ 
 ✓ Installing CNI 🔌 
 ✓ Installing StorageClass 💾 
 ✓ Joining worker nodes 🚜 
Set kubectl context to "kind-umang-cluster"
You can now use your cluster with:

kubectl cluster-info --context kind-umang-cluster

Have a question, bug, or feature request? Let us know! https://kind.sigs.k8s.io/#community 🙂

$ kind get clusters
umang-cluster

$ kubectl get nodes
NAME                          STATUS   ROLES           AGE    VERSION
umang-cluster-control-plane   Ready    control-plane   116s   v1.31.2
umang-cluster-worker          Ready    <none>          103s   v1.31.2
umang-cluster-worker2         Ready    <none>          103s   v1.31.2

$ docker ps
CONTAINER ID   IMAGE                  COMMAND                  CREATED         STATUS         PORTS                       NAMES
1a6aeb41b8ad   kindest/node:v1.31.2   "/usr/local/bin/entr…"   6 minutes ago   Up 5 minutes                               umang-cluster-worker2
d0d4330e4e87   kindest/node:v1.31.2   "/usr/local/bin/entr…"   6 minutes ago   Up 5 minutes                               umang-cluster-worker
0ca905d82421   kindest/node:v1.31.2   "/usr/local/bin/entr…"   6 minutes ago   Up 5 minutes   127.0.0.1:39241->6443/tcp   umang-cluster-control-plane

So by following the above things you will be able to create the cluster

Thank You 🙏🏻 ❤️

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