# Kubernetes Tutorial: The Basics How to learn Kubernetes in 2022 This guide is aimed to fast-track your Kubernetes learning by focusing on a practical hands-on overview guide.
When learning Kubernetes, you usually have an idea of some existing system you own and manage, or a website that you are building.
The challenge is understanding which Kubernetes building blocks you need in order to run your workloads on Kubernetes
The problem: "I want to adopt Kubernetes"
The problem: "I have some common existing infrastructure"
Our focus: Solving the problem by learning each building block in order to port our infrastructure to Kubernetes. ## Understanding Containers Before even looking at Kubernetes, you need to have a general understanding of containers like `docker`. Your workloads need to fit in containers in order to be shipped on Kubernetes.
Containers also have a bunch of assumptions that you need to meet. * Defining the container - `Dockerfile` * Serving traffic - Exposing ports * Configuration - mount config files & secrets or `env` variables * Data persistence - When a container is terminated, everything inside the container is gone * Container entrypoint - The main process that runs in the container. Your app ### Docker installation * Install Docker [here](https://docs.docker.com/get-docker/) * Let's take a look at [Wordpress on Docker Hub](https://hub.docker.com/_/wordpress) * Build our docker file ## Create Network ``` docker network create wordpress ``` ## Build & Test container images ### Wordpress example ``` cd kubernetes\tutorials\basics\ docker build -f dockerfiles/wordpress.dockerfile . -t aimvector/wordpress-example ``` * Run our Wordpress container ``` docker run -it --rm -p 80:80 --net wordpress aimvector/wordpress-example ``` The wordpress container will be visible on port 80 on `http://localhost/` ### MySQL example * We need a database, let's take a look at [MySQL on Docker Hub](https://hub.docker.com/_/mysql) * Build our MySQl container image ``` docker build -f dockerfiles/mysql.dockerfile . -t aimvector/mysql-example ``` * How do we run our MySQL ? We need to understand that databases require storage and state Just like installing software on a server, it will store its files in some directory. Mysql stores its files under `/var/lib/mysql` * We need a volume mount Let's see how to run this in docker ``` mkdir data docker run --rm -d ` --name mysql ` --net wordpress ` -e MYSQL_DATABASE=exampledb ` -e MYSQL_USER=exampleuser ` -e MYSQL_PASSWORD=examplepassword ` -e MYSQL_RANDOM_ROOT_PASSWORD=1 ` -v ${PWD}/data:/var/lib/mysql ` aimvector/mysql-example # we can see the container with docker ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES 92cde663a3f5 aimvector/mysql-example "docker-entrypoint.s…" 5 seconds ago Up 3 seconds 3306/tcp, 33060/tcp mysql ``` * Run Wordpress and connect it to MySQL ``` docker run -d ` --rm ` -p 80:80 ` --name wordpress ` --net wordpress ` -e WORDPRESS_DB_HOST=mysql ` -e WORDPRESS_DB_USER=exampleuser ` -e WORDPRESS_DB_PASSWORD=examplepassword ` -e WORDPRESS_DB_NAME=exampledb ` aimvector/wordpress-example ``` ### Clean up ``` docker rm -f wordpress docker rm -f mysql docker network rm wordpress rm data ``` ## Kubernetes Tools: kubectl To manage and work with Kubernetes, you need `kubectl`
Let's grab that from [here](https://kubernetes.io/docs/tasks/tools/) ## Run Kubernetes Locally * Install `kubectl` to work with kubernetes We'll head over to the [kubernetes](https://kubernetes.io/docs/tasks/tools/) site to download `kubectl` * Install the `kind` binary You will want to head over to the [kind](https://kind.sigs.k8s.io/) site * Create a cluster ``` kind create cluster --image kindest/node:v1.23.5 ``` ## Namespaces ``` kubectl create namespace cms ``` ## Configmaps [Environment Variables](https://kubernetes.io/docs/tasks/inject-data-application/define-environment-variable-container/) for pods [How to use](https://kubernetes.io/docs/concepts/configuration/configmap/) configmaps ``` kubectl -n cms create configmap mysql ` --from-literal MYSQL_RANDOM_ROOT_PASSWORD=1 kubectl -n cms get configmaps ``` ## Secrets [How to use](https://kubernetes.io/docs/concepts/configuration/secret/) secrets in pods ``` kubectl -n cms create secret generic wordpress ` --from-literal WORDPRESS_DB_HOST=mysql ` --from-literal WORDPRESS_DB_USER=exampleuser ` --from-literal WORDPRESS_DB_PASSWORD=examplepassword ` --from-literal WORDPRESS_DB_NAME=exampledb kubectl -n cms create secret generic mysql ` --from-literal MYSQL_USER=exampleuser ` --from-literal MYSQL_PASSWORD=examplepassword ` --from-literal MYSQL_DATABASE=exampledb kubectl -n cms get secret ``` ## Deployments * Deployment [documentation](https://kubernetes.io/docs/concepts/workloads/controllers/deployment/) cd kubernetes\tutorials\basics ``` kubectl -n cms apply -f yaml/deploy.yaml kubectl -n cms get pods ``` # Services Services [documentation](https://kubernetes.io/docs/concepts/services-networking/service/) ``` kubectl -n cms apply -f .\yaml\service.yaml kubectl -n cms get svc ``` # Storage Class StorageClass [documentation](https://kubernetes.io/docs/concepts/storage/storage-classes/) ``` kubectl get storageclass ``` # Statefulset Statefulset [documentation](https://kubernetes.io/docs/concepts/workloads/controllers/statefulset/) Let's deploy our `mysql` using what we learnt above: ``` kubectl -n cms apply -f yaml/statefulset.yaml kubectl -n cms get pods ``` ## Persistent Volumes [Documentation](https://kubernetes.io/docs/concepts/storage/persistent-volumes/) ## Port Forwarding We can access private service endpoints or pods using `port-forward` : ``` kubectl -n cms get pods kubectl -n cms port-forward 80 ``` ## Public Traffic In order to make our site public, its common practise to expose web servers via
a proxy or API gateway.
In Kubernetes, an Ingress is used. ## Ingress To use an ingress, we need an ingress controller ``` kubectl apply -f https://raw.githubusercontent.com/kubernetes/ingress-nginx/controller-v1.1.3/deploy/static/provider/cloud/deploy.yaml kubectl -n ingress-nginx get pods kubectl -n ingress-nginx --address 0.0.0.0 port-forward svc/ingress-nginx-controller 80 ``` Create an Ingress ``` kubectl -n cms apply -f yaml/ingress.yaml ```