By Mr. Prasanna Veerapandi, Associate Lecturer & Consultant, Software Engineering & Design Practice

1. Deploy and Manage Containers
on K8S
http://bit.ly/docker_k8s_talk
Prasanna Veerapandi (bala)
bala@nus.edu.sg

2. About me
Now
- Lecturer at Institute of System Science
- Creates and teaches
- Python For Data, Ops and Things
- Cloud DevOps Foundation
- Containers for Deploying and Scaling Apps
Past
- Application consultant - Web Application development & DevOps
- Mobile Application Developer

3. Objective
Introduction to containers
from a
Developer’s perspective

4. What is a container ?

5. Virtual Machines
Server
Host OS
Hypervisor (type 2)
Guest
OS
Run
time
App
#0
Guest
OS
Run
time
App
#0
Guest
OS
Run
time
App
#1
Virtualmachines
VMs virtualizes the hardware

6. Containers
Server
Linux
LXC
Runtime
App
#0
App
#0
Run
time
App
#1
Virtualmachines
Container
VMs virtualizes the hardware
Container virtualizes Linux
Server
Host OS
Hypervisor (type 2)
Guest
OS
Run
time
App
#0
Guest
OS
Run
time
App
#0
Guest
OS
Run
time
App
#1

7. LXC Enabling Technologies
Namespaces - isolation
- Virtualizes Linux resources (process, network, filesystem, etc) for one or
more processes
- Analogy: Java packages, XML namespaces
CGroups - resource limits
- Hard and soft limit on resources eg. CPU shares, memory, bandwidth, etc
Overlay filesystem - bottom of the well view
- Provides a unified view of multiple directories by transparently
overlaying and merging them

9. Docker
Container
Server
Linux
LXC
Runtime
App
#0
App
#0
Run
time
App
#1
A set of LXC management tools
for creating “containerize”
application
- Application running in their
own namespaces
- Their own view of the the
file systems
- Constrained to a specific
set of resources
An “image” format

10. Let’s Code
A simple web server using
NodeJS and Express

11. Cloning and Customizing the App
- Create an application directory
- Copy the files over to the new directory
- package.json - application manifest
- Files and directories
- (Re)Install the required libraries
- Customize the content

12. Containerize It
Applications’ files
node
Dockerfile
docker build -t myapp:latest .
myapp

13. Run It
Applications’ files
node
Dockerfile
docker run -d -p 3000:3000
--name app0 myapp:latest
myapp

14. Docker Workflow
App image
Running
deploy
build push
Container
registry
pull
deploy

15. Space and Volumes
- Containers are ephemeral
- Any files you create in the container will be gone once you remove
the container
- Mapping host directory into the container
- Sharing of common data
- Creating and saving artifacts
- Mapping a container’s volume into another container
- Data only container eg database
- Mapping storages into a container
- Data from NFS, other drives

16. Volumes
VOLUME /myapp/public
/data
docker run -d -v /data:/myapp/public
-p 3000:3000 --name app0 myapp:latest
Mounted under /myapp/public

18. Growing Big
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Servers with Docker Loadbalancer
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19. But…
Need to setup environment
Deal with hardware and software failures
Keeping services up and monitoring them
Build a infrastructure framework to deal with deployments
…

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“Ops”
Servers
“Dev”
Applications
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21. Or you can use

22. What is Kubernetes?
A container cluster management system
- Manage Docker, rkt
Support applications by providing the following
- scaling/replication, load balancing, rolling updates,
health checks, services discovery, etc.
Alternatives
- Docker Swarm, Mesos Marathon, Fleet

23. Kubernetes Architecture (vastly simplified)The picture can't be displayed.
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Kubernetesnodes
Kuberneres
Master
Kublet
kubectl

24. POD - a deployable unit of container(s)
localhost:3306
MySQL
database
Payara
Application Server
NodeJS

25. Deployment
kubectl run deployment/kapps --image=chukmunnlee/kapps:latest
--port=3000
Creates and schedules a pod
onto a node in the cluster
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3000

26. PODS are ephemeral

27. Services
kubectl expose deployment/kapps --port=8080 --target-port=3000
Provides location and
referential transparency by
providing a stable IP address
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3000
8080

28. Scaling
kubectl scale deployment/kapps --replicas=3
Replication controller resolves
differences between declared
and actual
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3000
8080
3000 3000

29. Pet vs Sheep/Cattle
Vertical scaling Horizontal scaling

30. Container Friendly Applications
https://12factor.net/