Introduction to Kubernetes

Marcin Wielgus

DRAFT

A little bit of history ...

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gs://kubernetes-release

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What does it look now?

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Ships

• Ship loading is complicated.

• It can be really time consuming to load and unload a ship, especially with multiple types of goods.

Ships

• Having containers makes loading and unloading much easier and efficient.

• To effectively use containers you need a proper infrastructure.

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Kubernetes

Greek for “Helmsman”; also the root of the words “governor” and “cybernetic”

• Manages container clusters

• Inspired and informed by Google’s experiences and internal systems

• cloud and bare-metal environments

• container runtimes

• 100% Open source, written in Go

Manage applications, not machines

Let’s build something!

Gossip Site

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image: pudelek.pl

What do we need?

• Front-end web servers to show the show the pages.

• Backend servers to perform “business logic”

• Web servers to provide images.• Database with gossips and

discussion boards.• Load Balancer.

Containers and Pods

Web Server

File Puller

Volume10.5.8.123

Pod - a set of container that are run together on the same machine and share volumes, ip address and can communicate via localhost.

Requirements

Container:• CPU, Memory• Volumes• Ports

Pod:• Node preferences• Affinity• Anti-affinity

Scheduling & Controlling

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Kubernetes Architecture

ETCD ApiServer

Scheduler

Controller Manager

Kubelet

SchedulerScheduler

User’s Pod

Kubelet

SchedulerScheduler

User’s Pod

Kubelet

SchedulerScheduler

User Pod

Master NodeWorker node

User requests

Replica Set

Replica Set controller makes sure that there is always the desired number of copies up

Web Serverr

File Puller

Web Serverr

File PullerWeb Server

File Puller

Deployment

Deployment takes care of different versions and rolling updates.

Web Serverr

File Puller

Web Serverr

File PullerWeb Server

File Puller

Web Serverr

File Puller

Web Serverr

File PullerWeb Server

File Puller

Update

Version 1.5Version 1.4

Services

Services make binding set of pods easily.

BackendBackend

Backend

backend.k8s10.5.210.220

BackendBackend

Backend

FrontendFrontend

FrontendFrontend

FrontendFrontend

Ingress

frontend.k8s10.5.210.220

BackendBackend

Frontend

fimages.k8s10.5.211.205

BackendBackend

Images

Load Balancer

gossip.ru/main/*

gossip.ru/images/*

Monitoring and Logging

• Container-level health checks.• Bundled with basic monitoring and

logging solution • Integration with:

• Datadog• ElasticSearch• Influxdb• Prometheus• Splunk• Stackdriver• Sysdig

Autoscaling

Adjusting:• Number of POD to CPU load or

custom metric.• Pod/container declared

requirements to the actual usage.• Number of nodes so that all pods

have place to live and the nodes are well utilized.

What else is in?

State of the Project

~45k Commits ~1100 UniqueContributors

Top 0.001% of all Github Projects

Contributors

Users

Kubernetes

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