Getting started

Basic terms: system parts

  • 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"

Installing Kubernetes locally

  • Kubernetes is a series of containers, CLI's and configurations

  • Many ways to install:

    • MacOS: Docker Desktop - Enable in Settings. Sets up everything inside Docker's existing Linux VM

      • Runs, configures Kubernetes Master containers

      • Manages kubectl install and certificates

      • Easily install, disable and remove from Docker GUI

    • Docker Toolbox on Windows - MiniKube. Uses VirtualBox to make Linux VM

      • Doesn't install kubectl, has to be installed separately

    • Your own Linux host or VM - MicroK8s. Installs Kubernetes right on the OS

      • Uses snap (rather apt or yum) for install.

      • Control MicroK8s service via microk8s. commands

      • kubectl accessible via microk8s.kubectl

      • Add an alias to your shell (.bash_profile): alias kubectl=microk8s.kubectl

  • Kuberneters in a Browser

Kubernetes 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. Controllers manage pods, you almost never manage pods yourself. There are many types of Controllers, including Deployment, ReplicaSet, StatefulSet, DaemonSet, Job, CronJob, etc.

  • Service: network endpoint to connect to a pod.

  • Namespace: Filtered group of objects in cluster.

  • Secrets, ConfigMaps, etc.

Kubernetes Run, Create and Apply

  • Kubernetes is evolving, and so is the CLI

  • We get 3 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)

Basic commands

  • kubectl version - shows a version of Client and Server

  • kubectl cluster-info

  • kubectl run my-nginx --image nginx - this will create a pod, replica set and a deployment

  • kubectl get pods - get current pods

  • kubectl get all - get all components

  • kubectl delete deployment my-nginx - delete named deployment

Scaling ReplicaSets

  • Start new deployment for one replica/pod

    kubectl run my-apache --image httpd

  • Scale deployment

    kubectl scale deploy/my-apache --replicas 2

    kubectl scale deployment my-apache --replicas 2 (these are same commands)

Inspecting Deployments

  • Get logs

    kubectl logs deployment my-apache

  • Get logs from pods with a given label

    kubectl logs -l run=my-apache

  • Stern for Kubernetes can be used to tail logs from multiple pods (

    brew install stern

    stern pod-query

  • Get pod info

    kubectl describe pod/<pod-id> (pod-id can be obtained with kubectl get pods)`

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