Kubernetes (k8s)

• Kubernetes, also known as K8s, is an open-source system for automating deployment, scaling, and management of containerized applications.
• origin of name: Greek, meaning: Helmsman or pilot

Container orchestrators

• Kubernetes
• Docker Swarm
• Mesos
  • Big Data
• Rancher

Kubernetes Cluster

• Nodes: Master and Worker

Kubernetes Resources

• Persistent entities in the Kubernetes system that represent state of your cluster
• The k8s REST API are also designed based on resources
• They are defined by kind attribute in yaml spec
• Example Pod spec

apiVersion: v1
kind: Pod # !important
metadata:
  name: webserver-pod
spec: # !important
  ....

• apiVersion: K8s API version
• kind: type of k8s resource
  • Pod
  • Deployment
  • Service
  • ConfigMap etc.
• metadata: to uniquely identify and describe a Kubernetes object
  • labels
  • name
  • namespace
  • annotations
  • finalizers etc.
• spec: desired state and characteristics of the object that we want to create.

Ways to run Kubernetes

• minikube
• Docker for Desktop
• Kubernetes in Docker (kind) : good for lot of testing
• Managed Kubernetes service in cloud
  • Amazon Elastic Kubernetes Service (EKS)
  • Azure Kubernetes Service (AKS)

docker: image -> container registry (ACR)
image -> container (running instance of image)