This document discusses Docker, an open-source containerization platform. It begins by explaining the need for containerization in complex systems development. It then covers Docker architecture, including images, containers, and registries. Key Docker commands are presented, like run, ps, and inspect. Best practices for Dockerfile configuration and container management are provided. Examples of building Nginx and Flask containers are shown.

2. Alexander Ryabtsev
http://djangostars.com/

4. Why do we need this?

Complex systems development

Deploying on test/prod. servers, developer machines

Different target OS

Different software versions

Etc

5. Virtualization
HARDWARE
HOST OS
HYPERVISOR
GUEST OS 1 GUEST OS 2 GUEST OS N
LIBRARIES LIBRARIES LIBRARIES
APP 1 APP 2 APP N

6. Containerization
HARDWARE
HOST OS
CONTAINERIZTION ENGINE
X X X
LIBRARIES LIBRARIES LIBRARIES
APP 1 APP 2 APP N

7. DOCKER
HARDWARE
HOST OS
DOCKER
LIBRARIES LIBRARIES LIBRARIES
APP 1 APP 2 APP N

8. What is Docker?
Open-source engine that automates the deployment of
applications into containers developed by Docker Inc
Based on:

libcontainer - container format

namespaces - isolation

cgroups - sharing

unionfs - layering

9. Platforms

Linux

Windows (over boot2docker)

MacOS (over boot2docker)

Cloud platforms
− Amazon EC2
− Rackspace Cloud
− Google Compute Engine
− etc

10. Requirements

Linux kernel with cgroups and namespaces features

x86_64 & amd64 only

appropriate storage driver
− dev mapper
− AUFS
− vfs
− btrfs

11. Hello world
sudo docker run -i -t ubuntu /bin/bash

sudo - you have to run all docker commands as
root

run - start container

-i - keeps STDIN open

-t - assign pseudo-TTY

ubuntu - image

/bin/bash - command (CMD)

12. Some commands

run

ps

inspect

pause / unpause

start / stop / restart

kill

13. Architecture

Image

Container

Registry

14. Images & Containers
write CONTAINER GOES HERE
read only curl example.com 701e38299831
read only ... 5171cea75fa4
read only apt-get install curl cc0f88ebb125
read only apt-get update b9474e097082
read only base image 447ff49a67a0

15. Life cycle
Image:

build
− do some action
− create intermediate image

create a container

remove
Container:
start
mount volumes
expose ports
run service
remove

16. Registry
https://registry.hub.docker.com/

Official repos

User repos

Public repos

Private repos

17. Dockerfile

FROM

RUN

COPY / ADD

ENV

EXPOSE

VOLUME

ENTRYPOINT / CMD

18. Best practices

Include only necessary context

Use a .dockerignore file

Avoid installing unnecessary packages

Use cache

Be care with volumes

Use environment varaibles (in RUN, EXPOSE, VOLUME)

19. HTTP-server example
NGINX
80/TCP
data

20. HTTP-server: Dockerfile
FROM ubuntu:latest
RUN apt-get update
RUN apt-get install -y nginx
RUN ln -sf /dev/stdout /var/log/nginx/access.log
RUN ln -sf /dev/stderr /var/log/nginx/error.log
VOLUME ["/usr/share/nginx/html"]
EXPOSE 80/tcp
CMD ["nginx", "-g", "daemon off;"]

21. HTTP-server: Commands
sudo docker build --tag='nginx' .
sudo docker run -p 8080:80 --rm nginx
sudo docker run
-p 8080:80
-v ~/docker_demo/nginx/html:/usr/share/nginx/html
--rm
nginx

22. APP-server example
Application
5000/TCP 6379/TCP
Redis
SRC

23. HTTP + APP example
from flask import Flask
from redis import Redis
import os
app = Flask(__name__)
redis = Redis(host='redis', port=6379)
@app.route('/')
def hello():
redis.incr('hits')
return 'Hello World! I have been seen %s
times.' % redis.get('hits')
if __name__ == "__main__":
app.run(host="0.0.0.0", debug=True)
FROM python:2.7
ADD . /code
WORKDIR /code
EXPOSE 5000/tcp
RUN pip install -r requirements.txt

24. --link parameter
sudo docker build --tag='app' .
sudo docker run -d --name redis redis
sudo docker run -d -p 5000:5000
--name app
--link redis:redis
app
python app.py

25. docker up (fig)
web:
build: .
command: python app.py
ports:
- "5000:5000"
volumes:
- .:/code
links:
- redis
redis:
image: redis

26. Orchestration tools

Fig / Docker Compose

Mesosphere / Marathon

Kubernetes / Mesos

etc

27. Docker true way

1 application = 1 container

Run process in foreground

Keep data out of container

No SSH

No manual configurations (or actions) inside container

28. Harsh reality

supervisor

docker exec

nsenter (from util-linux)

hard links

Docker ambassador

29. 3rd party apps

CoreOS, Fleet

Docker Swarm

Docker Machine

Panamax

etc

30. Usefull docs

Official documentation https://docs.docker.com/

Docker blog http://blog.docker.com/

Docker Hub https://registry.hub.docker.com/

The Docker Book

31. Thank you for
your attention!