Kubernetes from Zero to Hero

this blog is consists of topics within intro to K8s.

Welcome to learn k8s with me!!! [Kubernetes Crash Course for Absolute Beginners NEW] - YouTube

0. What’s K8s

a container orchestration tool.

• Trend from Monolith to Microservices.
• Increased usage of containers.
• Demand for a proper way managing those hundreds of containers.

the rise of containers in microservices technology actually resulted in applications that are now comprised of hundreds or sometimes maybe thousands of containers.

Managing those loads of containers across multiple environments using scripts and self-made tools an be really complex and sometimes even impossible.

• High Availability or no downtime
• Scalability or high performance
• Disaster recovery - backup and restore.

1. Kubernetes Architecture

• control node - several important processes

  

• worker nodes

master nodes are much more important than worker nodes

2. Main Kubernetes Components

2.1 Node & Pod

Node: a virtual or physical machine

IP adjust every time the pod restart,so -> service

2.2 Service &Ingress

Ingress: cause the node-ip is not very practical.

2.3 ConfigMap & Secret

change name: mogo-db-service -> mogo-db

! ConfigMap is for non-confidential data only! ->Secret

2.4 Volume

2.5 Deployment & StatefulSet

my-app died -> replicates everything!

Define blueprint for Pods: specify how many replicas you want to have

work with deployments instead of pods.

! DB can’t be replicated via Deployment!

DB has state -> data inconsistence - > StatefulSet

however, deploying StatefulSet not easy -> common practice: DB hosted outside of k8s cluster.

3. Kubernetes Configuration

talk to API server

C-M

each configuration file has 3 parts

4. Minikube & Kubeetcl - Setup k8s cluster locally

• what’s MiniKube & Kubeetcl?
• How to setup?

复查一下哪里出错了。

4.1 MiniKube & Kubeetcl

**MiniKube **

Master and Node processes run in ONE machine

Node: docker runtime pre-installed.

Kubeetcl: Command line tool for K8s cluster - interact

4.2 Deploy WebApp with MongoDB

4.2.1 Demo Project Overview

https://minikube.sigs.k8s.io/docs/start/

container or VM environment

本文参考环境：MacOS Sonoma 14.2

brew install hyperkit

Docker prefered!

	minikube start --vm-driver docker

😑 翻墙也不行，miniKube FAQ已经为我们提供方法权限问题按提示修改即可。

minikube start --image-repository='registry.cn-hangzhou.aliyuncs.com/google_containers'

Or Start your cluster

	minikube start --vm-driver=hyperkit

get status of nodes

	kubectl get nodes

	minikube status

4.2.2 Create Config Files

**MongoDB Endpoint **

• mongo-config.yaml

  

• mongo-secret.yaml

  

	echo -n mogouser | base64
	echo -n mogopassword | base64 

• mongo.yaml - Deployment & Service in 1 file, because they belong together.

  

  

  • label: for pods, label is a required field. for other compoments, it is optional.

    

    

  • Selector: which Pods belong to Deployment?

    

  

• Service: --- = you can have multiple YAML configurations within a file

  simple to keep port and target port the same.

  

  

How do we pass these environment variables to mongo application?

same with password

similar with webapp:

Configure external Service

4.2.3 Deploy all resources in MiniKube cluster

4.3 Interacting with K8s cluster

get all components in cluster

kubectl get all

kubectl get pod | configmap | secret

	kubectl --help

	kubectl get pod
	kubectle logs <podName>

Acess WebApp in Browser

kubectl get svc

minikube ip

不知道怎么回事，上面的不行，下面的行

minikube service webapp-service --url

5. Main Kubectl Commands

minikube start --image-repository='registry.cn-hangzhou.aliyuncs.com/google_containers'

kubectl create deployment nginx-delp --image=nginx

replicaset : a layer between deployment and pod.

kubectl get replicaset

Everything below Deployment is handled by k8s.

So let’s make a change. ->deployment

kubectl edit deployment nginx-depl

Auto-genetated configuration file with default values:

Debug pods

kubectl logs [pod-name]

Eg.

kubectl create deployment mongo-depl --image=mongo
kubectl get pod 

kubectl logs mongo-depl-558475c797-sb8nb

kubectl describe pod [pod name] 

好墨迹呀！！

Enter the container

kubectl exec -it [pod name] -- bin/bash

Delete deplyment & Apply configuration file

kubectl delete deployment [name]

Configuration files is a better way.

kubectl apply -f [file name]

Summarize

https://www.youtube.com/watch?v=UPJpmOKGKzU

看完三小时的课程后，学习openFaas，部署k3s+openfaas