# Kubernetes Install

> Markdown source of <https://docs.calebsargeant.com/computing/kubernetes/install/>.

## Architecture Terminology

- Kubernetes: the whole orchestration system

  > - K8s "k-eights" or Kube for short

- Kubectl: CLI to configure Kubernetes and manage apps

  > - Using "cube control" official pronunciation

- Node: Single server in the Kubernetes cluster

- Kubelet: Kubernetes agent running on nodes

- Control Plane: Set of containers that manage the cluster

  > - Includes API server, scheduler, controller manager, etcd, and more
  > - Sometimes called the master

![kubernetes architecture](_images/kubernetes-architecture.png)

## Installing Kubernetes

- Kubernetes is a series of containers, CLIs and configurations

- Many ways to install

- Docker Desktop: Enable in settings

  > - Sets up everything inside Docker's existing Linux VM

- Docker Toolbox on Windows: MiniKube

  > - Uses VirtualBox to make Linux VM

- Your Own Linux Host or VM: MicroK8s

  > - Installs Kubernetes right on the OS

- Kubernetes in a browser

  > - Try <http://play-with-k8s.com> or katacoda.com in a browser

## Container Abstractions

- **Pod:** one or more containers running together on one Node

  > - Basic unit of deployment. Containers are always in pods

- **Controller:** For creating/updating pods and other objects

  > - Many types of Controllers inc. Deployment, ReplicaSet, StatefulSet, DaemonSet, Job, CronJob, etc.

- **Service:** network endpoint to connect to a pod

- **Namespace:** Filtered group of objects in cluster

- Secrets, ConfigMaps, and more

## Kubectl Command Styles

- Kubernets is evolving, and so is the CLI

- We get three ways to create pods from the kubectl CLI

  > - `kubectl run` (changing to be only for pod creation)
  > - `kubectl create` (create some resources via CLI or YAML)
  > - `kubectl apply` (create/update anything via YAML)

## Our First Pod

### Creating Pods with kubectl

- Are we working?

  > - `kubectl version`

- Two ways to deploy Pods (containers): via commands, or via YAML

- Lets run a pod of the nginx web server!

  > - `kubectl run my-nginx --image nginx`

- Lets list the pod

  > - `kubectl get pods`

- Lets see all objects

  > - `kubectl get all`

### Pods -\> ReplicaSet -\> Deployment

![kubernetes pods](_images/kubernetes-pods.png)

### Cleanup

- Delete deployment

  > - `kubectl delete deployment my-nginx`

## Scaling ReplicaSets

- Start a new deployment for one replica/pod

  > - `kubectl run my-apache --image httpd`

- Lets scale it up with another pod

  > - `kubectl scale deploy/my-apache --replicas 2`
  > - `kubectl scale deployment my-apace --replicas 2`
  > - Same command
  > - deploy = deployment = deployments

## Inspecting Deployments

- `kubectl get pods`

- Get container logs

  > - `kubectl logs deploy my-apache --follow --tail 1`

- Get a bunch of details about an object including events!

  > - `kubectl logs -l run=my-apache`
  > - `kubectl describe pod/my-apache-xxxxxx-yyyyy`

- Watch a command (without needing `watch`)

  > - `kubectl get pods -w`

- In a seperate window

  > - `kubectl delete pod/my-apache-xxx-yyy`

- Watch the pod get re-created