12 factor ..IIX(-___-)XII''

http://12factor.net/

Codebase - One codebase tracked in revision control, many deploys
Dependencies - Explicitly declare and isolate dependencies
Config - Store config in the environment
Backing Services - Treat backing services as attached resources
Build, release, run - Strictly separate build and run stages
Processes - Execute the app as one or more stateless processes
Port binding - Export services via port binding
Concurrency - Scale out via the process model
Disposability - Maximize robustness with fast startup and graceful shutdown
Dev/prod parity - Keep development, staging, and production as similar as possible
Logs - Treat logs as event streams
Admin processes - Run admin/management tasks as one-off processes

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01-codebase.md

01. Codebase

1 app in 1 git repo

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02-dependencies.md

02. Dependencies

gem install natives

natives install --gemfile=Gemfile

bundle install --deployment

Question: How to vendor system tools e.g. imagemagick, curl?

Perhaps.. docker?

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03-config.md

03. Config

Ideas

a separate repo
store env files in repo
or store 1 env.yml, generate env files during deployment

# env.yml
default: &default
  DATABASE_URL: foo
  FOO: bar

development:
  <<: *default

staging:
  <<: *default
  DATABASE_URL: foo_staging
  BAR: foo

# yaml2env.rb
require 'yaml'
YAML.load_file('env.yml').each do |env_name, vars|
  File.open("env.#{env_name}", 'w') do |f|
    vars.each do |key, value|
      f.puts "#{key}=#{value}"
    end
  end
end

# Gemfile
gem 'dotenv-rails'

# .env.sample
DATABASE_URL=blablabla

# .gitignore
.env*
!.env.sample

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04-backing-services.md

04. Backing Services

Database

rm config/database.yml

# .env
DATABASE_URL=sqlite3://localhost/?database=db/{app}_development.sqlite3&pool=5&timeout=5000

DATABASE_URL=postgresql://postgres@localhost/{app}_development?encoding=unicode&pool=5&timeout=5000

DATABASE_URL=mysql://root@localhost/{app}_development?encoding=unicode&pool=5&timeout=5000