1.
Kubernetes Architecture
Janakiram MSV
Analyst | Advisor | Architect
Janakiram & Associates
Google Developer Expert

2.
Announcing
The Kubernetes Webinar Series
● Monthly webinar focused on helping you get started with Kubernetes
● Delivered by the experts from the container ecosystem
● Each webinar introduces a concept to accelerate your learning
● No specific prerequisites
○ Basic understanding of Docker will help
● All attendees will get $100 Google Cloud Platform Credits
● Win free annual and monthly subscriptions of MAPT eBook library
● The recording of this webinar will be available at Kubernetes.live

3.
Objectives
● A closer look at Kubernetes cluster
● Master components
● Node components
● Pods
● Labels & Selectors
● Replication Controllers
● Services

4.
Kubernetes Architecture
Kubernetes
Master
Node 1API
UI
CLI
Node 2
Node n
Node 3
Registry

5.
Kubernetes Master
API Server Scheduler Controller
etcd
API
UI
CLI

6.
Kubernetes Node
kube-proxy
Docker kubelet
Supervisord
fluentd
PodPod
Pod
Pod
Pod
Pod
Pod
Pod
Kubernetes
Master
AddonsDNS UI

7.
A Simple Containerized Application
Python
Web App
Redis
Database
Client

8.
Kubernetes Pod
● Group of one or more containers that are always co-located,
co-scheduled, and run in a shared context
● Containers in the same pod have the same hostname
● Each pod is isolated by
○ Process ID (PID) namespace
○ Network namespace
○ Interprocess Communication (IPC) namespace
○ Unix Time Sharing (UTS) namespace
● Alternative to a VM with multiple processes

9.
Labels & Selectors
● Key/value pairs associated with Kubernetes objects
● Used to organize and select subsets of objects
● Attached to objects at creation time but modified at any time.
● Labels are the essential glue to associate one API object with other
○ Replication Controller -> Pods
○ Service -> Pods
○ Pods -> Nodes

10.
Deploying a Pod
Pod Definition
Master
kube-p
roxyDocker kubelet
Supervisord
fluentd
Web Pod
Node
DB Pod
Pod Definition
Python
Redis

11.
Services
● An abstraction to define a logical set of Pods bound by a policy by to
access them
● Services are exposed through internal and external endpoints
● Services can also point to non-Kubernetes endpoints through a
Virtual-IP-Bridge
● Supports TCP and UDP
● Interfaces with kube-proxy to manipulate iptables
● Service can be exposed internal or external to the cluster

12.
Exposing Services
DB PodWeb
Pod
2
Web
Pod
1
Web
Pod
3
Client Node
Port
Cluster
IP

13.
Demo
Creating Pods & Services
Python Web App & Redis DB

14.
Replication Controller
● Ensures that a Pod or homogeneous set of Pods are always up and
available
● Always maintains desired number of Pods
○ If there are excess Pods, they get killed
○ New pods are launched when they fail, get deleted, or terminated
● Creating a replication controller with a count of 1 ensures that a Pod is
always available
● Replication Controller and Pods are associated through Labels

15.
kube-p
roxyDocker kubelet
Supervisord
fluentd
Web
Pod
1
Scaling Pods with Replication Controller
RC Definition
Master
Node
Web
Pod
2
Web
Pod
3
3
DB Pod

16.
Demo
Scaling Pods with Replication Controller

17.
Summary
● Kubernetes Master runs the API, Scheduler and Controller services
● Each Node is responsible for running one or more Pods
● Pods are the unit of deployment in Kubernetes
● Labels associate one Kubernetes object with the other
● Replication Controller ensures high availability of Pods
● Services expose Pods to internal and external consumers

18.
Upcoming Webinar
A Closer Look at Kubernetes Pods
9 AM PST, 26th October
This session will discuss the best practices of creating,
deploying, and managing Pods. We will take a closer look at
the storage and networking architecture of containers
running in the same Pod.
Register at kubernetes.live for the upcoming webinars

19.
Thank You!
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info@kubernetes.live