How To Setup Ruby on Rails with Postgres

1. Init project

在本機端，我們無需安裝任何的 ruby 環境，我們只需要透過 docker hub 上提供的�image，就可以幫助我們產生專案 source code

$ docker run --rm -v $(pwd):/usr/srv/app -w /usr/srv/app rails rails new . --skip-bundle
$ docker run --rm -v $(pwd):/usr/src/app -w /usr/src/app ruby:2.3.1 bundle lock

# option
$ docker run --rm -v $(pwd):/usr/src/app -w /usr/src/app ruby:2.3.1 bundle lock --update

2. Dockerfile

我們需要為這個專案添加一個專屬的 Dockerfile，執行安裝 Gemfile 內相依套件，並在最後啟動 rails server

FROM ruby:2.3.3
RUN apt-get update -qq && apt-get install -y build-essential libpq-dev nodejs
RUN mkdir /myapp
WORKDIR /myapp
ADD Gemfile /myapp/Gemfile
ADD Gemfile.lock /myapp/Gemfile.lock
RUN bundle install
ADD . /myapp
CMD bundle exec rails s -p 3000 -b 0.0.0.0

3. Installing Requirements & Setup configuration

Gemfile

# Add gem "pg" into Gemfile 
# Add gem "rspec-rails" into Gemfile

gem "pg"
group :development, :test do
  gem 'rspec-rails', '~> 3.6'
end

Once configured, your database.yml should contain something like this:

default: &default
  adapter: postgresql
  encoding: unicode
  pool: 5
  timeout: 5000

development:
  <<: *default
  database: helloworld
  username: develop
  password: password1
  host: helloworld_postgres_1

# Warning: The database defined as "test" will be erased and
# re-generated from your development database when you run "rake".
# Do not set this db to the same as development or production.
test:
  <<: *default
  database: helloworld
  username: test
  password: password1
  host: helloworld_postgres_1


production:
  <<: *default
  database: helloworld
  username: prod
  password: password1
  host: helloworld_postgres_1

4. docker-compose.yml

version: '3.3'
services:
  postgres:
    image: postgres
    volumes:
      - postgres:/var/lib/postgresql/data
  web:
    build: .
    command: bundle exec rails s -p 8888 -b '0.0.0.0'
    volumes:
      - .:/myapp
    ports:
      - "3000:8888"
    depends_on:
      - postgres
volumes:
  postgres:

5. Setting Up Postgres

$ docker exec -it helloworld_postgres_1 psql -U postgres
postgres=# \?
\l[+]   [PATTERN]      list databases
\du[S+] [PATTERN]      list roles
\q                     quit psql
postgres=# create role develop with superuser login password 'password1';
postgres=# create role test with superuser login password 'password1';
postgres=# create role prod with superuser login password 'password1';

6. Rails command

$ docker exec -it helloworld_web_1 rails generate controller home index
$ docker exec -it helloworld_web_1 rake db:setup
$ docker exec -it rails g scaffold Post title:string body:text
$ docker exec -it rake db:migrate
$ docker exec -it helloworld_web_1 rails generate rspec:install
$ docker exec -it bundle exec rspec

Build & Run

• docker-compose build & docker-compose up -d

Q&A

• Difference between links and depends_on in docker_compose.yml