The document provides an overview of virtualization and its solutions, comparing traditional virtualization with Docker technology, highlighting the pros and cons of each. It explains Docker's architecture, commands related to images and containers, and how to manage them using Docker Compose and Docker Swarm for microservices. Additionally, it covers use cases for Docker, emphasizing its speed, lightweight nature, and portability.

2. Agenda
● What is Virtualization?
● What is Virtualization trying to solve?
● Traditional Virtualization
● What is Docker?
○ Docker vs. Virtual Machine
● Images, Containers and Registry
● Volume Mounting, Port Publishing, Linking
● Docker Compose
● Demo
● Docker Swarm
● Docker Use Cases

3. What is
Virtualization?
What is it trying to
solve?
- Many systems on top of a single
powerful hardware
- Consistency across
environments
- Changing one thing without
affecting the other

4. Traditional
Virtualization
Pros:
- More isolation
Cons:
- Heavy

5. Container Technology

6. Docker vs. VMs
Pros:
- Speed (faster to spin up)
- Lightweight
- Portability (size)
- Density (Layered System -
AuFS)
Cons:
- Less isolated

7. What is Docker?

8. Docker Engine

9. Architecture on Linux Platform

10. Architecture on Windows Platform

11. Docker Image
A snapshot of a Linux filesystem.
Example Docker commands that operate on images:
● images: List all local images
● tag: Tag an image
● pull: Download image from repository
● rmi: Delete a local image (will also remove intermediate images if no
longer used)

12. Docker Container
A running instance of an image.
Example Docker commands that operate on containers:
● ps -a: List all containers (including stopped)
● run: Create a container from an image and execute a command
in it
● rm: Delete a container
● exec: Run a new command in a running container

14. Docker Registry
● A registry that stores and delivers images
● Private Registries
○ Private to user or company
● Public Registries
○ Example: Official Docker Hub Registry (https://hub.docker.com/)
■ Pull images from existing repositories
■ Create your own repositories
■ Push images to your own repositories

15. Mount Volumes
● Shared folders
● docker run –it –v /host/dir:/container/dir ubuntu bash
○ /container/dirinside the container will correspond to /host/dir in the
host
● docker run –it --volumes-from container_name ubuntu bash
○ Run a new container with the same volumes as an existing one

16. Publish Port
● Map ports
● docker run -d -p 8080:80 nginx
○ Map container’s port 80 to host’s port 8080
○ Use the official Nginx image
■ Which is configured to automatically run Nginx inside a container
○ On host, can then browse to http://localhost:8080/ in a web browser to
see the website

17. Dockerfile
- Reusable Images in different
environments (stage, dev, prod)
- Layered Filesystem (AuFS)
- Domain Specific Language
FROM python:3.4
ENV PYTHONUNBUFFERED 1
RUN mkdir /code
WORKDIR /code
ADD . /code/
RUN pip install -r requirements.txt

18. Docker Compose
- Written in YAML
- Make microservice containers
behave like a single system

19. Docker Compose
version: '2'
services:
db:
image: postgres
web:
build: .
command: |
bash -c 'bash -s <<EOF
./wait-for-it.sh db:5432 &&
python myapp/manage.py makemigrations &&
python myapp/manage.py migrate &&
python myapp/manage.py loaddata myapp/initial.json &&
python myapp/manage.py runserver 0.0.0.0:8000
EOF'
volumes:
- .:/code
ports:
- "8000:8000"
depends_on:
- db

20. DEMO

21. Docker Swarm
- Clustering
- Scheduling
- Load Balancing
- Fault-tolerance
- Rolling updates

22. Docker Use Cases
● Consistent Environments
● Quick evaluation of software
● Microservices

23. Q/A