Zero to DevOps in

Under an Hour with

http://slides.com/dalealleshouse/k8/live

Agenda

  • What is Kubernetes?

  • Kubernetes Goals

  • Kubernetes Basic Architecture

  • Awesome Kubernetes Demo!

  • What Now?

What is Kubernetes?

  • AKA K8S (K-8 letters-S)
  • Greek for Ship's Captain (κυβερνήτης)
  • Google's Open Source Container Management System
    • https://github.com/kubernetes
    • Lessons Learned from Borg/Omega
    • K8S is speculated to replace Borg
  • Released June 2014
  • 1.0 Release July, 2015
  • Currently in Version 1.19
  • Highest Market Share
  • Bundled with Docker

K8S Goals

  • Container vs. VM Focus
  • Portable (Run everywhere)
  • General Purpose
    • Any workload - Stateless, Stateful, batch, etc...
  • Flexible (consume wholesale or a la carte)
  • Extensible
  • Automatable
  • Advance the state of the art
    • cloud-native and DevOps Focused
    • mechanisms for slow monolith/legacy migrations

K8S Architecture

More Architecture Info

  • Omega: flexible, scalable schedulers for large compute clusters
    • https://research.google.com/pubs/pub41684.html
  • Large-scale cluster management at Google with Borg
    • https://research.google.com/pubs/pub43438.html
  • Borg, Omega, and Kubernetes
    • https://research.google.com/pubs/pub44843.html
  • https://github.com/kubernetes/community

Demo System

https://github.com/dalealleshouse/zero-to-devops

Setup

  • Full setup instructions available in repo
  • Cluster
    • Docker Desktop
  • DNS - Hosts File
    • 127.0.0.1 demo.com
    • 127.0.0.1 status.demo.com
  • Docker Hub
    • Images downloaded and built locally before demo

Deployments

  • Deployments consist of pods and replica sets
    • Pod - One or more containers in a logical group
    • Replica set - controls number of pod replicas
kubectl run html-frontend --image=html-frontend:1.0 --port=80 --env STATUS_HOST=status.demo.com
kubectl run java-consumer --image=java-consumer:1.0
kubectl run ruby-producer --image=ruby-producer:1.0
kubectl run status-api --image=status-api:1.0 port=5000
kubectl run queue --image=rabbitmq:3.6.6-management
# View the pods created by the deployments
kubectl get pods

# Run docker type commands on the containers
kubectl exec -it *POD_NAME* -- bash
kubectl logs *POD_NAME*
# Create a deployment for each container in the demo system

Services

Services provide a durable end point

kubectl expose pod queue --port=15672,5672 --name=queue

The above only creates an internal endpoint, below creates an externally accessible endpoint

kubectl expose pod html-frontend --port=80 --name=html-frontend --type=NodePort
kubectl expose pod status-api --port=80 --target-port=5000 \
	--name=status-api --type=NodePort

The website is now externally accessible at the cluster endpoint

kubectl logs java-consumer
kubectl logs java-consumer -f
# Notice the java-consumer cannot connect to the queue
# The following command makes the queue discoverable via the name queue
# Running the command again shows that it is connected now
# Create an endpoint for the HTML page as the REST API Service

Infrastructure as Code

The preferred alternative to using shell commands is storing configuration in yaml files. See the kube directory

kubectl delete -f kube/
kubectl delete pods --all
kubectl create -f kube/
# Delete all objects made previously
# Each object has a matching file in the kube directory
# Recreate everything

Default Monitoring

K8S has a default dashboard

kubectl proxy

http://localhost:8001/api/v1/namespaces/kubernetes-dashboard/services/https:kubernetes-dashboard:/proxy/

kubectl -n kubernetes-dashboard describe secret \
	$(kubectl -n kubernetes-dashboard get secret \
    	| grep admin-user | awk '{print $1}')
# Get the authentication token
# configuration specific - most cloud providers have something similar
# create a tunnel from the cluster to the local machine

Scaling

K8S will automatically load balance requests to a service between all replicas. Making subsequent requests to the html page reveals different pod names.

kubectl scale deployment html-frontend --replicas=3

K8S can create replicas easy and quickly

# Scale the NGINX deployment to 3 replicas

Auto-Scaling

K8S can scale based on load.

kubectl autoscale deployment java-consumer --min=1 --max=5 --cpu-percent=50
# Run this repeatedly to see # of replicas created
# Also, the "In Process" number on the web page will reflect the number of replicas
# Maintain between 1 and 5 replicas based on CPU usage
kubectl get deployments

Self Healing

K8S will automatically restart any pods that die.

docker ps -f label=io.kubernetes.container.name=html-frontend
# View the html-frontend pods
# Containers are regenerated immediately
# Forcibly shut down container to simulate a node\pod failure
docker rm -f *CONTAINER*
docker ps -f label=io.kubernetes.container.name=html-frontend

Health Checks

If the endpoint check fails, K8S automatically kills the container and starts a new one

kubectl get pods
...
        livenessProbe:
          httpGet:
            path: /healthz.html
            port: 80
          initialDelaySeconds: 3
          periodSeconds: 2
        readinessProbe:
          httpGet:
            path: /healthz.html
            port: 80
          initialDelaySeconds: 3
          periodSeconds: 2

Specify health and readiness checks in yaml

# Find frontend pod
# Simulate a failure by manually deleting the health check file
# See the restart in the event logs
kubectl exec *POD_NAME* -- rm /usr/share/nginx/html/healthz.html
kubectl get events | grep *POD_NAME*

Rolling Deployment

K8S will update one pod at a time so there is no downtime for updates

kubectl set image deployment/html-frontend html-frontend=dalealleshouse/html-frontend:2.0

Viewing the html page shows an error. K8S makes it easy to roll back deployments

kubectl rollout undo deployment html-frontend
# Roll back the deployment to the old image
# Run repeadly to see the number of available replicas
# Update the deployment image
kubectl get deployments

More Cool Stuff

The demo covers a subset of the most notable K8S features. Some more to investigate on your own:

 

Helm

Secrets
Volumes
Stateful Sets
Daemon Sets
Jobs
Cron Jobs
So Much More...

What Now?

  • K8S Docs
    • https://kubernetes.io/docs/home/
  • Free Online Course from Google
    • https://www.udacity.com/course/scalable-microservices-with-kubernetes--ud615

Thank You!

Zero to DevOps in Under an Hour with Kubernetes

By Dale Alleshouse

Zero to DevOps in Under an Hour with Kubernetes

The benefits of containerization cannot be overstated. Tools like Docker have made working with containers easy, efficient, and even enjoyable. However, management at scale is still a considerable task. That's why there's Kubernetes. Come see how easy it is to create a manageable container environment. Live on stage (demo gods willing) you'll witness a full Kubernetes configuration. In less than an hour, we'll build an environment capable of: Automatic Binpacking, Instant Scalability, Self-healing, Rolling Deployments, and Service Discovery/Load Balancing.

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