Kubernetes 101

whoamiDevOps Engineer @ Spreaker

h"p://twi"er.com/jnardiello

What to expect

A Kubernetes primer

Tips, tricks, sweat and bloodreal life experience bringing k8s to produc5on

High-load system

Distributed architecture

Our whole infrastructure is on AWS

Our pain points

Underused machines

Autoscaling would take minutes

Non-athomic provisioning makes it difficult to roll-out upgrades or migrate services

The solu)on: Docker!Perfectly determinis/c, ephemeral, light-

weight

Unfortunately containers are just half

of the equa3on

Real costs will emerge as you try to make containers work

together

Kubernetes

def.

(Opinionated) Orchestra1on framework to organise and deploy container-based

applica1ons

Agnos&c sandbox where you provide the desired state of your

services/apps. Kubernetes aims to take care of everything else

Disclaimer!

From the outside Kubernetes is a black box

But inner mechanisms makes it a complex beast to master

We got the cookies!a.k.a. features

Self-healing servicesHealth checks on your containers,

rescheduling failing jobs

Dynamic scalingEnsure current state and scale your pods (but

it's s4ll on you to scale the nodes)

Networking and rou/ngRoute traffic to your containers

Efficient physical resources usageScheduling containers on physical/vms nodes

according to their effec7ve needs

Enough talking

Crea%ng a clusterMULTIZONE=1 KUBERNETES_PROVIDER=aws \KUBE_AWS_ZONE=eu-west-1b NON_MASQUERADE_CIDR="172.16.0.0/14" \SERVICE_CLUSTER_IP_RANGE="172.16.0.0/16" DNS_SERVER_IP="172.16.0.10" \MASTER_IP_RANGE="172.17.0.0/24" CLUSTER_IP_RANGE="172.18.0.0/16" \MASTER_SIZE=m3.medium NODE_SIZE=m3.medium NUM_NODES=1 \./cluster/kube-up.sh

h"ps://asciinema.org/a/4xnz9hc3lvs6zp3eakrf2qcjn

$ kubectl get nodes

NAME STATUS AGEip-172-20-0-209.eu-west-1.compute.internal Ready 47mip-172-20-0-210.eu-west-1.compute.internal Ready 47mip-172-20-0-211.eu-west-1.compute.internal Ready 47mip-172-20-0-212.eu-west-1.compute.internal Ready 47mip-172-20-0-213.eu-west-1.compute.internal Ready 47m

kubectl is your local CLI command center.

You can issue commands to the cluster either by kubectl or directly calling REST APIs exposed by the master

We got the nodes, we are ready

Our first container on kubernetes!

YAML all the things!

PodsA pod is a group of one or more containers. Pods are the smallest

deployable units that can be created and managed in Kubernetes.

Replica(on ControllersA replica*on controller ensures that a specified number of pod

“replicas” are running at any one *me

DeploymentsPod + Replica-onController

apiVersion: extensions/v1beta1kind: Deploymentmetadata: name: dummy-workerspec: replicas: 1 template: metadata: labels: app: dummy-worker spec: containers: - name: dummy-worker image: jnardiello/forever env: - name: SOME_ENV_VAR value: envvarvalue resources: limits: cpu: "256m" memory: "128Mi" requests: cpu: "5m" memory: "8Mi"

ServicesA Kubernetes Service is an abstrac0on which defines a logical set

of Pods and a policy by which to access them.

kind: Servicemetadata: name: dummy-worker-servicespec: ports: - port: 80· targetPort: 8000 protocol: TCP selector: app: dummy-worker externalIPs: [53.8.3.2]

There are different types of servicesNodePorts, proxied by the master

LoadBalancer, crea'ng an actual ELB on AWS

Ingress [beta] - WARNING, do not use

Deploy the containerh"ps://asciinema.org/a/7c42c8itmyz3982p6fmo9ecvi

Resilient applica,onsh"ps://asciinema.org/a/2bxo51ond7ac4haaguneingmv

Kubernetes is truly amazing(for POCs)

Ba#le-tested clusterA long way before reaching produc4on ready

There will be blood!

Opinionated Logging

Opinionated Monitoring

Master skynet, then implement your own solu4on

Custom metrics-based AutoscalingOpsFactory/Kappa

These topics are for another /me(We should probably do Kubernetes102)

Ques%ons?@jnardiello