Files for dockerizing and .env new Rails App

.env

# Rails secret
SECRET_KEY_BASE=NEW_SECRET

DB_POOL=10
DATABASE_URL=postgres://CHANGE_ME:CHANGE_ME123@db/CHANGE_ME_dev

# Puma port
PORT=3000

# Rails outputs to console if this env exists
RAILS_LOG_TO_STDOUT=true-if-you-want-logs-to-stdout-instead-of-a-file

database.yml

defaults: &defaults
  adapter: postgresql
  encoding: unicode
  pool: <%= ENV["DB_POOL"] || ENV['RAILS_MAX_THREADS'] || 5 %>
  reconnect: true

development: &development
  <<: *defaults
  # These are defined in docker-compose.yml
  host: db
  username: CHANGE_ME
  password: CHANGE_ME123
  database: <%= ENV['DATABASE_NAME'] || 'CHANGE_ME_dev' %>

test:
  <<: *development
  database: <%= ENV['TEST_DATABASE_NAME'] || 'CHANGE_ME_test' %>

production:
  <<: *defaults
  url: <%= ENV['DATABASE_URL'] %>

docker-compose.yaml

version: '2'
services:
  db:
    container_name: CHANGE_ME-db
    restart: always
    image: postgres:9.6.4-alpine
    environment:
      POSTGRES_MULTIPLE_DATABASES: CHANGE_ME_dev,CHANGE_ME_test
      POSTGRES_USER: CHANGE_ME
      POSTGRES_PASSWORD: CHANGE_ME123
    ports:
      - 5432:5432
    volumes:
      - CHANGE_ME_pg_data:/var/lib/postgresql/data

  CHANGE_ME:
    container_name: CHANGE_ME
    restart: always
    build: .
    env_file: .env
    command: sh -c "bundle exec puma -C config/puma.rb"
    volumes:
      - .:/CHANGE_ME
    ports:
      - 3000:3000
    links:
      - db
    depends_on:
      - db

volumes:
  CHANGE_ME_pg_data:
    driver: local

Dockerfile

FROM ruby:2.5.0

# Get required packages
RUN apt-get update -qq && apt-get install -y build-essential libpq-dev nodejs

# Set up working directory
ENV DIR CHANGE_ME
RUN mkdir /$DIR
WORKDIR /$DIR

# Set up gems
ADD Gemfile ./Gemfile
ADD Gemfile.lock ./Gemfile.lock
RUN gem install bundler
RUN bundle install --jobs 20 --retry 5

# Finally, add the rest of our app's code
ADD ./ ./

EXPOSE 3000

CMD bundle exec puma -C config/puma.rb

new_rails.sh

# Only this needs to be changed
NAME=sth
# Create a new secret
SECRET=$(rails secret)
# Create a new Rails app with postgres and cd into its folder
rails new $NAME -B --database=postgresql
cd $NAME
# Download from gist the needed files
files=( .env Dockerfile docker-compose.yaml )
for i in "${files[@]}"
do
   curl -O https://gist.githubusercontent.com/romdim/0fe67845943125eea35fce5dfdc8390e/raw/$i
done
curl -L https://gist.githubusercontent.com/romdim/0fe67845943125eea35fce5dfdc8390e/raw/database.yml > ./config/database.yml
# Change needed strings
sed -i "" "s/CHANGE_ME/$NAME/g" .env ./config/database.yml Dockerfile docker-compose.yaml
sed -i "" "s/NEW_SECRET/$SECRET/g" .env
touch Gemfile.lock
docker-compose build
docker-compose run --rm $NAME rails db:create
docker-compose run --rm $NAME rails db:migrate