This is a presentation I gave on 4Developers conference. http://2016.4developers.org.pl/en/program/speakers/hodowany-adam/

1. Ruby on Rails
& Docker
Why should I care?
Adam Hodowany

2. About me
• Adam Hodowany
• Ruby and JavaScript developer in Monterail
• @adhodak

3. Docker Less
DevOps Developer story

4. I wrote an app!
Now what?

5. $ bundle exec rails server -p 80
It is a joke. Please don’t do it.

6. Duh

7. But
($7 + $9) ÷ month

8. > UserAnswer.count
=> 158_565

9. http://giphy.com/gifs/ohdY5OaQmUmVW

10. VPS it is

12. Repeatability

13. Infrastructure as Code

14. Vagrant + Ansible

15. Vagrant
• “Development environments made easy”
• Virtual Machine without overhead
• Free, local VPS for testing provisioning scripts
• Local staging

16. # Vagrantfile
Vagrant.configure(2) do |config|
config.vm.box = "ubuntu/trusty64"
config.vm.network "forwarded_port", guest: 80, host: 8080
config.vm.network "forwarded_port", guest: 3000, host: 3030
end
$ vagrant up
# break things
$ vagrant destroy
$ vagrant up

17. Ansible
• Automation tool
• Configuration using .YML files
• No client on the server

18. # build-server.yml
---
- hosts: all
remote_user: "{{ deploy_user }}"
roles:
### Server provisioning roles:
- { role: linux-prereqs }
- { role: postgresql }
- { role: rbenv }
- { role: ruby }
- { role: nginx }
### Site specific roles:
- { role: prepare_site }
- { role: copy-env }
- create database
- copy database.yml
- copy nginx config

19. Docker

20. Docker:
your application in a
container
Image: KMJ at the German language Wikipedia

21. Container
1. Application
2. All dependencies
3. Common interface
4. ???
5. PROFIT

22. $ bundle exec rails server
$ php artisan serve
$ python manage.py runserver
$ docker run docker-image

23. How is it different from VM?
Virtual Machine: Docker:
https://www.docker.com/what-docker

24. # Dockerfile
FROM ruby:2.2.0
RUN apt-get update -qq && apt-get install -y build-essential nodejs && gem install bundler
ENV APP_HOME /myapp
RUN mkdir $APP_HOME
WORKDIR $APP_HOME
ADD Gemfile $APP_HOME/Gemfile
ADD Gemfile.lock $APP_HOME/Gemfile.lock
RUN bundle install
ADD . $APP_HOME
CMD ["bundle", "exec", "rails", "server", "--binding", "0.0.0.0"]
- Base Image
- Copy whole application to the image
|- Default “run” command

25. $ docker build -t my-project .
$ docker run -p 3000:3000 my-project
host:container

26. Linking containers
$ docker run -d --name db postgres
$ docker run --link db:db my-project
# config/database.yml
development:
host: db
...

27. Volumes
$ docker run -v /home/hodak/data:/data my-project
or: shared directories
(or files)
(but most likely directories)
host:container

28. Docker repositories
• Docker Hub
• Official
• Free public repositories
• Alternatives exist
• Self-hosted
• Installed with… Docker
or: GitHubs for Docker images

29. 99 official repositories including:
nginx, redis, node, postgres,
elasticsearch, wordpress,
jenkins, ruby…
Maintained by projects creators

30. Thousands of unofficial,
public repositories
http://gph.is/VxbrxV

31. Docker in
Development

32. Docker Machine

33. Volumes are great
• My misconception: code always either in container,
or always out of it.
# Dockerfile
ADD . app_dir/
Makes sure app directory
is always in built image
Enables code reload for development
$ docker run -v $(pwd):/app_dir my-project

34. Docker Compose
$ docker build -t my-project .
$ docker run -d --name db postgres
$ docker run --link db:db -p "3000:3000" my-project

35. $ docker run -d --name db postgres
$ docker run --link db:db -p "3000:3000" --env-file .env
my-project

36. $ docker run -d --name db postgres
$ docker run --link db:db -p "3000:3000" --env-file .env -
v /home/hodak/code/my-project:/my-project my-project

37. $ docker run -d --name db postgres
$ docker run -d --name redis redis
$ docker run -d --name sidekiq --link redis:redis --link db:db --env-file
.env my-project bundle exec sidekiq
$ docker run --link db:db --link redis:redis -p "3000:3000" --env-file .env
-v /home/hodak/code/my-project:/my-project my-project

38. # docker-compose.yml
db:
image: postgres
web:
build: .
command: bundle exec rails server --binding 0.0.0.0
ports:
- "3000:3000"
links:
- db
volumes:
- .:/myapp
env_file: .env
$ docker-compose build
$ docker-compose up

39. # docker-compose.yml
db:
image: postgres
redis:
image: redis
sidekiq:
build: .
command: bundle exec sidekiq
volumes:
- .:/myapp
links:
- db
- redis
env_file: .env
web:
build: .
command: bundle exec rails server --binding 0.0.0.0
ports:
- "3000:3000"
links:
- db
- redis
volumes:
- .:/myapp
env_file: .env

40. Use Cases
• Ruby on Rails agency - meh?
• Microservices
• Especially in different technologies
• Working with Freelancers

41. Admesh
github.com/admesh/admesh

43. $ ./configure
$ make
$ make install

45. # Dockerfile
COPY ./lib/admesh-0.98.2.tar.gz $APP_HOME/admesh.tar.gz
RUN tar -zxvf admesh.tar.gz &&
cd $APP_HOME/admesh-0.98.2 &&
./configure &&
make &&
make install

46. Continuous Integration
with Docker

47. Typical Rails-CI setup
$ cp config/codeship.database.yml config/database.yml
$ rvm use 2.1.1
$ bundle install
$ export RAILS_ENV=test
$ bundle exec rake db:drop db:create db:structure:load
$ bundle exec rspec

48. Development CI
Ruby version
Bundler version
Ruby version
Bundler version

49. Development CI
Ruby version
Bundler version
Ruby version
Bundler version
Staging Production
Ruby version
Bundler version
Ruby version
Bundler version

50. • More tricky dependencies
• ImageMagick
• ADMesh
• …

51. Development CI Docker Repository
Dev
Build
Productio
n
Build
Staging Production

52. • Image that has proven itself
• No errors
• Specs passed

53. $ cp config/codeship.database.yml config/database.yml
$ rvm use 2.1.1
$ bundle install
$ export RAILS_ENV=test
$ bundle exec rake db:drop db:create db:structure:load
$ bundle exec rspec

54. - Start Postgres
|- Build production image
- Set up database
- Run specs
After specs pass:
Send image
to Docker Hub
# origin/master -> master
$ BRANCH_NAME=`echo $GIT_BRANCH | cut -d '/' -f 2-`
$ docker rm --force $(docker ps -aq) || echo "ok"
$ docker run -d --name db postgres
$ docker build -t my-project -f Dockerfile.prod .
$ docker run --link db:db -e RAILS_ENV=test my-project bundle exec rake db:create d
$ docker run --link db:db -e RAILS_ENV=test my-project bundle exec rspec
$ docker tag my-project hodak/my-project:$BRANCH_NAME
$ docker push hodak/my-project:$BRANCH_NAME

55. Docker in production

56. # build-server.yml
---
- hosts: all
remote_user: "{{ deploy_user }}"
roles:
### Server provisioning roles:
- { role: linux-prereqs }
- { role: postgresql }
- { role: rbenv }
- { role: ruby }
- { role: nginx }
### Site specific roles:
- { role: prepare_site }
- { role: copy-env }

57. # build-server.yml
---
- hosts: all
remote_user: "{{ deploy_user }}"
roles:
### Server provisioning roles:
- { role: linux-prereqs }
- { role: nginx }
- { role: docker }
### Site specific roles:
- { role: prepare_site }
- { role: copy-env }
- create database
- copy database.yml
- copy nginx config

58. • Still must configure nginx
• Pull image from Docker repository
• Not touching GitHub at all
• Synchronise starting containers
• Monitoring

59. Data-only container pattern
$ docker run --name dbdata postgres echo "Data-only container for
postgres"
$ docker run -d --volumes-from dbdata --name db postgres

60. docker-compose?

61. Just a script

62. #!/bin/bash
docker run --name dbdata postgres echo "Data-only container for
postgres" || echo "already started"
docker run -d --volumes-from dbdata --name db --restart=always
postgres || docker start db
docker pull hodak/my-project:master
docker tag hodak/my-project:master my-project
docker run --link db:db my-project bundle exec rake db:create
db:migrate
docker rm --force my-project || echo "not yet created"
docker run -d --link db:db --name my-project --restart=always --env-file
.env -p "8080:8080" my-project

63. Ansible

64. tasks:
- name: application container
docker:
name: my-project
image: hodak/my-project:master
state: reloaded
pull: always
links:
- "db:db"
ports:
- "8080:8080"
restart_policy: always

65. Custom deploy script
for Capistrano

66. upstart / systemd /
supervisor / monit

67. Is it worth it?

68. Thank you!
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