Kubernetes is an open-source system for managing containerized applications and services. It includes a master node that runs control plane components like the API server, scheduler, and controller manager. Worker nodes run the kubelet service and pods. Pods are the basic building blocks that can contain one or more containers. Labels are used to identify and select pods. Replication controllers ensure a specified number of pod replicas are running. Services define a logical set of pods and associated policy for access. They are exposed via cluster IP addresses or externally using load balancers.

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!
Send your Feedback / Questions / Comments
info@kubernetes.live