Kubernetes Test Drive

by Rob Richardson

  @rob_rich

https://robrich.org/

About Me

Rob Richardson is a software craftsman building web properties in ASP.NET and Node, React and Vue. He's a frequent speaker at conferences, user groups, and community events, and a diligent teacher and student of high quality software development. You can find this and other talks on https://robrich.org/presentations and follow him on twitter at @rob_rich.

What is Kubernetes?

Industry standard container orchestration engine
by Google
best known for rolling updates and auto scaling

What is an Orchestration Engine?

Given a cluster of machine(s)
We specify containers' desired state
The engine makes it happen

We don't specify which machine does what

Kubernetes

Hosts containers

Either Docker containers or ...
are there any others really?

What is Docker?

Docker is an ecosystem around Container Virtualization

Containers vs VMs

Source: http://www.zdnet.com/article/what-is-docker-and-why-is-it-so-darn-popular/

Containers

Containers virtualize and share the host kernel

Containers must run on the kernel for which they were built:

• Linux
• Windows Server

Host Docker in a VM

Ephemeral, Isomorphic, Deterministic Hardware

• Each copy is identical
• Don't upgrade, replace
• Many instances from one file
• Built the same each time
• Saved in a small configuration file

Docker: Dev & Ops Communication

Download: https://robrich.org/slides/welcome-to-docker/docker-ecosystem.pdf

Docker -> Kubernetes

K8s: "Given a Docker image ..."

Kubernetes Scenario

source: https://vitalflux.com/quick-glance-at-kubernetes-architectural-building-blocks/

Elements

Pod

apiVersion: v1
kind: Pod
metadata:
  name: nginx
  labels:
    app: nginx
spec:
  containers:
  - name: nginx
    image: nginx:1.19.3
    ports:
    - containerPort: 80

source: https://kubernetes.io/docs/user-guide/walkthrough/

Deployment

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
  labels:
    app: nginx
spec:
  replicas: 3
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.19.3
        ports:
        - containerPort: 80

source: https://kubernetes.io/docs/concepts/workloads/controllers/deployment/

Service

apiVersion: v1
kind: Service
metadata:
  name: nginx-service
  labels:
    app: nginx
spec:
  selector:
    app: nginx
  type: NodePort
  ports:
  - port: 80
    protocol: TCP

source: https://kubernetes.io/docs/concepts/services-networking/connect-applications-service/

Service Types

Mapping Service to Pod

Service.yaml

kind: Service
...
spec:
  selector:
    app: nginx
...

Pod.yaml (or template in Deployment.yaml)

kind: Pod
metadata:
  labels:
    app: nginx
...

kubectl UI

source: https://github.com/kubernetes/dashboard

kubectl UI

Warning

It's really easy to change things.

Next time you deploy
your changes will be lost.