Docker and
Kubernetes

by Rob Richardson

@rob_rich

https://robrich.org/

About Me

Rob Richardson is a software craftsman building web properties in ASP.NET and Node, Angular and React. 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.

Docker is

• ephemeral
• isomorphic
• deterministic

Docker is

• ephemeral (short-lived)
• isomorphic (unchanging)
• deterministic (same every time)

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

virtualize and share the host kernel

must match host kernel:

• Linux containers run on a Linux host
• Windows Server containers run on a Windows Server host

Host Docker in a VM

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

Dockerfile

FROM node

WORKDIR /app

COPY package.json .
RUN npm install

COPY . .

ENV NODE_ENV production
ENV PORT 3000
EXPOSE 3000

CMD ["npm", "start"]

Layered Filesystem

Source: https://docs.docker.com/engine/userguide/storagedriver/aufs-driver/

Layered Filesystem

source

Layered Filesystem

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

Docker Magic

Docker Magic

Want another?

"docker run" it again

What is Kubernetes?

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

Kubernetes

Hosts containers

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

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:1.7.9
    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:1.7.9
        ports:
        - containerPort: 80

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

Deployment apiVersion

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.