Course

Begineers Guide - FreeCodeCamp

Image

Image for k8s-web-hello - Docker Hub Image for k8s-web-nginx - Docker Hub

Problem Statement

1. Learn basic commands related to minikube and kubectl
2. Build a custom image of a simple node application
3. Initialize and scale pods using deployment based on the custom image
4. Create nodeport and loadbalancer services
5. Rollout new image changes to pods

Installation and Setup:

- choco install kubernetes-cli
- choco install minikube
- Enable-WindowsOptionalFeature -Online -FeatureName Microsoft-Hyper-V -All

Cluster Operations:

- minikube start --driver=virtualbox | hyperv (create cluster)
- minikube delete
- minikube status (cluster status)
- minikube ip (node IP)
- minikube dashboard (Minikube GUI)
- minikube ssh (login to cluster)
  - docker ps | grep <filter-name> (use filter to find containers)
  - docker exec -it <container-id> sh (login to a container)
	- hostname
	- hostname -i
	- curl <ip>
	- exit

Instance Info.:

- kubectl cluster-info (list cluster info)
- kubectl get nodes (list all nodes)
- kubectl get namespaces (list all namespaces)
- kubectl get pods (list all pods)
- kubectl get deployments (list all deployments)
- kubectl get services (list all services along with cluster IPs)

- kubectl get pods -o wide (list pods with important attributes)
- kubectl get pods --namespace=<namespace> (list pods within a namespace)

Pod Operations:

- kubectl run <pod-name> --image=<image-name> (create a pod from an image)
- curl <pod-ip> (connect to pod)
- kubectl describe pod <pod-name> (describe a pod)
- kubectl delete pod <pod-name> (delete a pod)

Deployment Operations:

- kubectl create deployment <deployment-name> --image=<image-name> (create a deployment)
- kubectl describe deployment <deployment-name> (describe a deployment)
- kubectl delete deployment <deployment-name> (delete a deployment)
- kubectl scale deployment <deployment-name> --replicas=<desired-replicas> (scale pods)
- kubectl expose deployment <deployment-name> --port=<internal-port> --target-port=<external-port> (expose an external port)

Service Operations: ClusterIP (default) | NodePort | LoadBalancer

- kubectl expose deployment <deployment-name> --type=<service-type> --port=<internal-port>

Rolling Update:

- kubectl set image deployment <deployment-name> <pod-name>=<hub-ID>/<new-image>:<tag>
- kubectl rollout status deployment <deployment-name>

Delete all resources in default namespace:

- kubectl delete all --all

Automation of deployments and services:

- kubectl apply -f deployment.yaml (create manifest resources)
- kubectl delete -f deployment.yaml (delete manifest resources)

Notes:

1. Docker enables separation of an application from underlying infrastructure. whereas,
   Kubernetes is a container orchestration tool that provides load balancing and simplies container management on multiple hosts.

2. A pod is a smallest deployment unit in a kubernetes cluster. It is a collection of tightly coupled containers which communicate via localhost. whereas,
   A node is a unit in a kubernetes cluster that provides allocates necessary computing and storage resources to pods. It maintains lifecycle of pods.
	
3. In a typical Kubernetes setup, We can deploy applications in Pods, which are then scheduled onto Nodes within a Cluster. The control plane ensures the desired state of the    cluster and monitors the health of nodes and pods, making Kubernetes a powerful platform for container orchestration and management.
   
4. A pod is automatically initialized when a deployment is created.

5. If no service type is mentioned, A ClusterIP service is automatically initialized when a deployment is exposed and it is accessible only from nodes within the cluster.
   minikube ssh & curl <cluster-ip>:<external-port>
   
6. A service of type NodePort or LoadBalancer is accessible from a browser.
   minikube service <service-name> | curl <node-ip>:<random-port>
  
7. Kubernetes automatically creates desired number of pods if any is removed.