This document provides 7 reasons to start using Docker: 1) Docker utilizes Linux containers which provide isolation and density with low overhead; 2) Dockerfiles provide a simple way to automate application deployment; 3) Docker ensures identical environments for development, testing and production; 4) Docker simplifies deployments by packaging applications and dependencies; 5) Docker facilitates building platforms as code for scaling applications; 6) Docker aligns with the twelve-factor app methodology for building cloud-native apps; 7) Interest and capabilities around Docker are growing rapidly with new projects like CRIU and CoreOS.

1. 7 REASONS TO START USING
DOCKER
TARAS LYAPUN

2. https://flic.kr/p/dd2R3Ld

3. DOCKER IS NOT A
NEW VAGRANT!
3
REASON #1

4. LINUX CONTAINER
• OPERATING SYSTEM–LEVEL VIRTUALIZATION
• CGROUPS
• NAMESPACE
4

5. 5

6. 6
VIRTUAL MACHINE CONTAINER
ISOLATION COMPLETE ALMOST
COMPLETE
DENSITY x1 x3
OVERHEAD HIGH LOW
STARTUP SPEED 30 - 60 sec ~1 second

7. DOCKER IS SIMPLE!
7
REASON #2

8. DOCKERFILE
8
FROM ubuntu
RUN apt-get install -y python
ADD ./app /app
RUN pip install -r /app/requirements.txt
WORKDIR /app
EXPOSE 8000
VOLUME /app/logs
CMD /app/gunicorn.sh

9. COMMAND LINE INTERFACE
9
~ docker build -t test-image .
~ docker run -d -p 8000:8000
-v /var/logs/docker:/app/logs
—restart=always
test-image
~ docker push your-repo/test-image

10. IDENTITY AND
REPEATABILITY OF DEV,
TEST AND PROD
ENVIRONMENT
10
REASON #3

11. VAGRANT
11

12. DOCKER
12

13. FIG
13
web:
build: .
command: python app.py
links:
- db
ports:
- "8000:8000"
db:
image: postgres
~ fig up
http://www.fig.sh/

14. IDEAL CI + CD*
*from my point of view
14

15. SIMPLE DEPLOYMENT
15
REASON #4

16. BEFORE DOCKER
16

17. AFTER DOCKER
17

18. BEFORE DOCKER
• ---
• # INSTALL ELASTICSEARCH
• # INSTALL APT KEY
• - APT_KEY: URL=HTTP://PACKAGES.ELASTICSEARCH.ORG/GPG-KEY-ELASTICSEARCH
STATE=PRESENT
• # SET DEDICATED REPOSITORY
• - APT_REPOSITORY: REPO='DEB HTTP://PACKAGES.ELASTICSEARCH.ORG/
ELASTICSEARCH/{{ES_VERSION}}/DEBIAN STABLE MAIN' STATE=PRESENT
• # INSTALL ELASTICSEARCH WITH DEPENDANCIES
• - NAME: INSTALL ELASTICSEARCH
• APT: NAME={{ ITEM }} STATE=LATEST FORCE=YES
• TAGS: ELASTICSEARCH
• WITH_ITEMS:
• - ELASTICSEARCH
• - OPENJDK-7-JRE-HEADLESS
• - OPENNTPD
• NOTIFY: INIT ELASTICSEARCH
• # SET LIMITS.CONF
• - NAME: LIMITS.CONF TUNING
• LINEINFILE: DEST=/ETC/SECURITY/LIMITS.CONF LINE="{{ ITEM }}"
• TAGS: ELASTICSEARCH
• WITH_ITEMS:
• - 'ELASTICSEARCH SOFT NOFILE 32000'
• - 'ELASTICSEARCH HARD NOFILE 32000'
• # ENSURE SERVICE STARTED
• - SERVICE: NAME=ELASTICSEARCH STATE=STARTED
• # INSTALL PLUGINS
• - INCLUDE: PLUGINS.YML
18

19. AFTER DOCKER
~ DOCKER PULL DOCKERFILE/ELASTICSEARCH
~ DOCKER RUN -D -P 9200:9200 -V /VAR/DATA:/DATA
DOCKERFILE/ELASTICSEARCH
19
• ---
• # INSTALL ELASTICSEARCH
• # INSTALL APT KEY
• - APT_KEY: URL HTTP
STATE=PRESENT
• # SET DEDICATED REPOSITORY
• - APT_REPOSITORY
ELASTICSEARCH/{{ES
• # INSTALL ELASTICSEARCH
• - NAME: INSTALL ELASTICSEARCH
• APT: NAME={{ ITEM
• TAGS: ELASTICSEARCH
• WITH_ITEMS:
• - ELASTICSEARCH
• - OPENJDK-7-JRE
• - OPENNTPD
• NOTIFY
• # SET LIMITS
• - NAME LIMITS
• LINEINFILE
• TAGS: ELASTICSEARCH
• WITH_ITEMS
• - 'ELASTICSEARCH
• - 'ELASTICSEARCH
• # ENSURE
• - SERVICE
• # INSTALL
• - INCLUDE

20. DOCKERFILE
20
FROM ubuntu
RUN apt-get install -y python
ADD ./app /app
RUN pip install -r /app/requirements.txt
WORKDIR /app
EXPOSE 8000
VOLUME /app/logs
CMD /app/gunicorn.sh

21. SIMPLE ROLLBACK
~ DOCKER STOP NEW_CONTAINER
~ DOCKER START OLD_CONTAINER
21

22. IMAGE REUSE
FROM IDEAL-PYTHON-ENVIRONMENT
# SPECIFIC CODE
22

23. EASY TO BUILD YOUR
OWN PLATFORM
23
REASON #5

24. WHY MAY YOU NEED PAAS?
• A LOT OF PROJECTS
• SERVICE-ORIENTED ARCHITECTURE
• A LOT OF TESTING ENVIRONMENTS
• CONTINUOUS DEPLOYMENT
• SCALABILITY
24

25. OPENSOURCE PAAS BUILT WITH DOCKER
• DOKKU
• DEIS
• FLYNN
• BUILD YOUR OWN
25

26. DOCKER FORCES YOU
TO THINK ABOUT
SCALE
26
REASON #6

27. THE TWELVE-FACTOR APP
• DECLARATIVE FORMAT FOR SETUP AUTOMATION
• CLEAN CONTRACT WITH UNDERLYING OS
• SUITABLE FOR DEPLOYMENT ON MODERN CLOUD PLATFORMS
• MINIMIZE DIVERGENCE BETWEEN DEV AND PROD
• CAN SCALE UP WITHOUT SIGNIFICANT CHANGES TO TOOLING
OR ARCHITECTURE
http://12fact2o7 r.net

28. 1. CODEBASE
One codebase tracked in revision control, many deploys
28

29. 2. DEPENDENCIES
29
Explicitly declare and isolate dependencies

30. 3. CONFIG
30
Store config in the environment
• SETTINGS_LOCAL.PY
• ~ DOCKER RUN -D -E SMTP_SERVER_PASSWORD=12345
PROJECT/APP

31. 4. BACKING SERVICES
31
Treat backing services as attached resources
• DOCKER RUN -D —NAME=DB POSTGRES
• DOCKER RUN -D —LINK DB:DB PROJECT/APP
• MULTIHOST: HTTP://STACKOVERFLOW.COM/QUESTIONS/18285212/
HOW-TO-SCALE-DOCKER-CONTAINERS-IN-PRODUCTION

32. 5. BUILD, CONFIG, RELEASE
32
Strictly separate build and run stages
BUILD:
DOCKER BUILD .
CONFIG:
DOCKER CREATE
RELEASE:
DOCKER START

33. 6. PROCESSES
Execute the app as one or more stateless processes
33
DOCKER CONTAINER STATELESS BY DEFAULT

34. 7. PORT BINDING
34
Export services via port binding
~ DOCKER RUN -P 8000:80 PROJECT/APP

35. 8. CONCURRENCY
35
Scale out via the process model

36. 9. DISPOSABILITY
Maximize robustness with fast startup and graceful
shutdown
36
~ DOCKER STOP CONTAINER_NAME
~ DOCKER START CONTAINER_NAME

37. 10. DEV/PROD PARITY
37
Keep development, staging, and production
as similar as possible
SLIDE # 11

38. 11. LOGS
38
Treat logs as event streams
~ DOCKER LOGS CONTAINER_NAME

39. 12. ADMIN PROCESSES
Run admin/management tasks as one-off processes
39
~ DOCKER RUN PROJECT/APP /BIN/RUN_GUNICORN.SH
~ DOCKER RUN PROJECT/APP /BIN/RUN_CELERY.SH
~ DOCKER RUN PROJECT/APP PYTHON MANAGE.PY MIGRATE
~ DOCKER EXEC CONTAINER_NAME PYTHON MANAGE.PY ANYTHING

40. DOCKER IS A NEW
BUZZ WORD*
40
REASON #7
* in a good sense

41. INTEREST GROWING
March 2013 October 2014
41

42. CRIU
•FREEZE A RUNNING APPLICATION
•CHECKPOINT IT TO A HARD DRIVE
•RESTORE AND RUN THE APPLICATION
42

43. CORE OS
•NEW RE-ARCHITECTED LINIX DISTRIBUTION
•MINIMAL RAM USAGE
•APPLICATIONS RUN AS DOCKER CONTAINERS
•DESIGNED FOR SCALE
43

44. QUESTIONS, COMMENTS, THOUGHTS?
TARAS LIAPUN
@TLYAPUN
TARASLYAPUN@GMAIL.COM
44