Ops for Dev at Cogniance, 2015

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!