Docker - next big thing

By @jwo for HoustonRB

I've been working in Docker for a couple of months, including an engagement to move a complicated multi-server setup to Docker, where you can `docker-compose up` and have a complete setup up and running.

It's useful for developing Rails 2.3 apps as well as orchestrating complicated deployments. I've found there's no need to use chef/ansible with Docker, but it can absolutely be done.

We'll create a Nginx+Rails(puma)+Postgres+Redis+Memcached server setup, and get it online on both our Macs and on a cheap'ish Digital Ocean droplet.

Transcript

1. Docker - next big thing Jesse Wolgamott Docker - next big thing By @jwo for HoustonRB 0
3. Docker Run in linux, just like production It's like heroku, for development
4. Laws of Docker 1 Process per Container "Containers" are servers
5. Standard Rails App Rails PostgreSQL Redis Memcached Sidekiq
6. Startup - Development Clone bundle rake db:setup brew install postgresql createdb brew install redis brew install memcached foreman start
7. Startup - Production install ruby from source. maybe rbenv? sudo apt-get install postgresql, redis, memcached bundle create database and user rake db:migrate configure nginx and unicorn
8. ETOOMANYDIFFS New users, many dependencies, such frustration
9. Startup, Dev and Live 1. g i t c l o n e 2. d o c k e r - c o m p o s e b u i l d 3. d o c k e r - c o m p o s e u p
10. Comparison vs Chef No need for chef or ansible for most cases Deploy and you're good
11. Docker Compose Was "fig" (older documentation) Fancy term: "Coordination" Real World: connects your DB to your Rails
12. docker-compose.yml m y s q l d a t a : i m a g e : c o g n i t e e v / e c h o v o l u m e s : - / v a r / l i b / m y s q l d b : b u i l d : m y s q l : l a t e s t e x p o s e : - " 3 3 0 6 " v o l u m e s _ f r o m : - m y s q l d a t a a p p : b u i l d : . c o m m a n d : b u n d l e e x e c r a i l s s - p 3 0 0 0 - b ' 0 . 0 . 0 . 0 ' v o l u m e s : - . : / m y a p p p o r t s : - " 3 0 0 0 : 3 0 0 0 " l i n k s : - d b
13. Boot2docker Have to have it so your Macs can run Linux in your Linux
14. HOWTO Persist Data (Like Postgres, etc Data) Have your db data directory connect to a "data container" m y s q l d a t a : i m a g e : c o g n i t e e v / e c h o v o l u m e s : - / v a r / l i b / m y s q l d b : b u i l d : m y s q l : l a t e s t e x p o s e : - " 3 3 0 6 " v o l u m e s _ f r o m : - m y s q l d a t a
15. HOWTO Deploy your docker SSH into your main box g i t c l o n e d o c k e r - c o m p o s e b u i l d d o c k e r - c o m p o s e s t o p & & d o c k e r - c o m p o s e s t a r t
16. HOWTO Get a main box with docker 1. Digital Ocean $5 plan 2. Choose Docker 3. Win.
17. HOWTO Edit your Rails locally Do everything the same except: instead of http://192.168.59.103:3000/ http://localhost:3000
18. HOWTO run migrations d o c k e r - c o m p o s e r u n a p p r a k e d b : m i g r a t e
19. HOWTO Environment files Add in a .env file like you normally would. Gitignore it. m y s q l : e n v _ f i l e : D o c k e r C o n f i g / . e n v v o l u m e s _ f r o m : - m y s q l d a t a c o n t a i n e r
20. HOWTO database.yml p r o d u c t i o n : a d a p t e r : m y s q l 2 d a t a b a s e : y o l o _ p r o d u c t i o n u s e r n a m e : < % = E N V [ ' M Y S Q L _ U S E R ' ] % > p a s s w o r d : < % = E N V [ ' M Y S Q L _ P A S S ' ] % > h o s t : m y s q l p o r t : 3 3 0 6
21. HOWTO SSH into your boxes 1. Don't 2. Instead, run a process like you would heroku d o c k e r - c o m p o s e r u n a p p / b i n / b a s h
22. HOWTO Monitor your boxes Prometheus, by SoundCloud folk, rules. p r o m e t h e u s : b u i l d : d o c k e r _ c o n f i g / p r o m e t h e u s p o r t s : - " 9 0 9 0 : 9 0 9 0 " l i n k s : - c o n t a i n e r e x p o r t e r c o n t a i n e r e x p o r t e r : i m a g e : p r o m / c o n t a i n e r - e x p o r t e r p o r t s : - " 9 1 0 4 : 9 1 0 4 " v o l u m e s : - / s y s / f s / c g r o u p : / c g r o u p - / v a r / r u n / d o c k e r . s o c k : / v a r / r u n / d o c k e r . s o c k
23. DockerFile F R O M p h u s i o n / p a s s e n g e r - r u b y 2 2 R U N a p t - g e t u p d a t e - q q & & a p t - g e t i n s t a l l - y b u i l d - e s s e n t i a l R U N m k d i r / m y a p p W O R K D I R / m y a p p A D D . / m y a p p R U N b u n d l e i n s t a l l
24. Services Docker intentionally breaks upstart and most things that start systems The Dockerfile, instead, has a "CMD" (one cmd) that runs when started This is basically the docker way
25. HOWTO Run more than one service (assuming you want to say, run Inspeqtor to notify you of crashes) Install runit (pronounced 'run-it') CMD is "/usr/sbin/runsvdir-start" # A d d r u n i t s t a r t u p s R U N m k d i r / e t c / s v / i n s p e q t o r A D D i n s p e q t o r . r u n i t / e t c / s v / i n s p e q t o r / r u n R U N m k d i r / e t c / s v / m y s q l A D D m y s q l . r u n i t / e t c / s v / m y s q l / r u n R U N c h m o d + x / e t c / s v / i n s p e q t o r / r u n R U N c h m o d + x / e t c / s v / m y s q l / r u n # L i n k r u n i t s t a r t u p s c r i p t s R U N l n - s / e t c / s v / m y s q l / / e t c / s e r v i c e / m y s q l R U N l n - s / e t c / s v / i n s p e q t o r / / e t c / s e r v i c e / i n s p e q t o r # r e m o v e t h e u p s t a r t c o n f i g d i r e c t o r y R U N r m - r f / e t c / i n i t
27. Yeah So that part is rough around the edges Docker REALLY wants you to do 1 process per container It strips all else away besides what you start But runit can work
28. Finding Images Images are on https://registry.hub.docker.com/
29. HOWTO Reverse Engineer Dockerfiles 1. Check out the Image Dockerfile 2. Copy and Paste 3. Make sure you're on same linux OS. Ubuntu. CoreOS. Debian. (likely more).
30. JWO Rule of Docker Images What if I told you that using other people's (even official) docker images lead to more problems than they solve? — Jesse Wolgamott (@jwo) April 27, 2015
31. HOWTO Scale number of app servers 1. d o c k e r - c o m p o s e s c a l e a p p = 2 2. Use NGINX as reverse proxy 3. Have ngnix server port 80, server to many upstream u p s t r e a m a p p _ s e r v e r s { s e r v e r 1 2 7 . 0 . 0 . 1 : 8 0 8 0 ; s e r v e r 1 2 7 . 0 . 0 . 1 : 8 0 8 1 ; } Possible way to automate: http://jasonwilder.com/blog/2014/03/25/automated-nginx- reverse-proxy-for-docker/
32. HOWTO Have a larger disk size on boot2docker b o o t 2 d o c k e r d e s t r o y b o o t 2 d o c k e r i n i t - - d i s k s i z e = 2 0 0 0 0 (Yeah, that deletes all stuff and you start over)
33. HOWTO See what's running, and stop them d o c k e r p s C O N T A I N E R I D I M A G E C O M M A N D C R E A T 5 5 5 b 3 b 4 e 3 1 f a f i v e h u n d r e d _ a p p : l a t e s t " b u n d l e e x e c r a i l s s 2 m i n 6 a 5 b b 7 6 6 f 7 4 5 p o s t g r e s : l a t e s t " / d o c k e r - e n t r y p o i n t . d o c k e r k i l l 5 5 5 b 3 b 4 e 3 1 f a
34. Demo
35. Conclusion 1. Docker is extremely cool 2. Fast, easy'ish (appropriate levels of easy) Try it out: GitHub / jwo / blocker