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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

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

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

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