Pods101

Demystifying

theNuts&Boltsof

KubernetesArchitecture

Pods101

2

Who Am I?

• PrincipalSystemsDevelopmentEngineeratDellEMC

• WorkedwithVMware&CGI

• DockerCaptain|DockerCommunityLeader

• CollabnixSlack–1800+Members

• DockerLabs–500+tutorials

http://www.collabnix.com

3

Pod - Concepts

• WhatisPod?

• PodDeployment

• Multi-Container

• PodNetworking

• Inter-Pod&Intra-PodNetworking

• PodLifecycle

• PodManifestFile

4

Atomic Unit of Scheduling

Virtualization

Docker

Kubernetes

VM

Container

Pod

5

How Pods are deployed?

Cluster

Master

Scheduler

APIServer

Pod

Container

6

Scaling the Pods to accommodate increasing traffic

WorkerNode

Master

Scheduler

APIServer

Pod

Container

7

What if node resources is getting insufficient?

WorkerNode

Master

Scheduler

APIServer

Pod

Container

8

What if node resources is getting insufficient?

Cluster

Master

Scheduler

APIServer

Pod

Container

Worker-2

Worker-1

9

What if node resources is getting insufficient?

Cluster

Master

Scheduler

APIServer

Pod

Container

Worker-2

Worker-1

10

2 Containers in a same Pod

Cluster

Master

Scheduler

APIServer

Pod

Container

Worker-2

Worker-1

11

Pod Networking

Pod1

MainController

:8080

10.0.30.50

Pod2

Supporting

Controller

:7777

10.0.30.60

Supporting

Controller

:3000

Howdoesthesecontainersinside

PodscommunicatewithExternal

World?

13

Network Namespace

Pod1

MainController

:8080

10.0.30.50

Pod2

Supporting

Controller

:7777

10.0.30.60

Supporting

Controller

:3000

10.0.30.50:8080

10.0.30.50:3000

HowdoesonePodtalktoanother

Pod?

WelcometoInter-PodCommunication..

15

Pod Networking

Pod1

MainController

:8080

10.0.30.50

Pod2

Supporting

Controller

:7777

10.0.30.60

Supporting

Controller

:3000

PodNetwork

HowdoesIntra-Pod

communicationtakeplace?

17

Intra-Pod Communication

Pod1

MainContainer

Supporting

Container

:8080

:3000

10.0.30.50

:8080:3000

Localhost

18

A Look at Pod Manifest

19

Get a shell to a running Container

VerifyingtheOperatingSystem

20

Get a shell to a running Container

Verifying the index page

root@nginx-pod:/# echo Hello shell demo > /usr/share/nginx/html/index.html

StagesofLifeCycleofPod

Lifecycle of a Pod

Pending Running

Succeeding

Pod

Pod

Pod

Failed

Pod

APIServer

Manifest

Demo

• DeployingYourFirstNginxPod

• ViewingYourPod

• WhereisyourPodrunningon?

• PodOutputinJSON

• ExecutingCommandsagainstPod

• TerminatingaPod

• Addinga2ndcontainertoaPod