[RUBY] Build a development environment for Docker + Rails6 + Postgresql

Premise

We introduced Docker so that team members who have not built a Rails environment can easily run the project locally without the hassle of building the environment. Since I am building the Rails environment locally, I created the project locally so that both Docker and local direct can work. It is assumed that Docker is already installed.

environment

• macOS Catalina 10.15.4
• Ruby 2.7.1
• Rails 6.0.3.2
• PostgreSQL 12.3
• Docker version 19.03.12

Create new project

$ mkdir myapp; cd $_
$ rails new . --skip-coffee --skip-turbolinks --database=postgresql

Introduced dotenv-rails to manage environment variables

Depending on the environment variable, you can choose to run it with Docker or directly locally.

Gemfile

gem 'dotenv-rails'

install gem

$ bundle install

The following is an example of setting environment variables when running with Docker.

.env

DATABASE_HOST=db
DATABASE_USER=postgres
DATABASE_PASSWORD=secret

Set DATABASE_HOST = localhost to run directly locally.

File creation / editing for Docker

docker-compose.yml

version: '3'
services:
  db:
    image: postgres
    volumes:
      - ./tmp/db:/var/lib/postgresql/data
    ports:
      - "5433:5432"
    environment:
      POSTGRES_USER: 'postgres'
      POSTGRES_PASSWORD: 'secret'
      POSTGRES_DB: 'db'

  webpacker:
    build: .
    command: bundle exec bin/webpack-dev-server
    volumes:
      - .:/myapp
    ports:
      - "8080:8080"

  web:
    build: .
    command: /bin/sh -c "rm -f /myapp/tmp/pids/server.pid && bundle exec rails s -p 3000 -b '0.0.0.0'"
    volumes:
      - .:/myapp
    ports:
      - "3000:3000"
    depends_on:
      - db
      - webpacker

dockerfile

FROM ruby:2.7.1
 
ENV LANG C.UTF-8

#Install the required libraries
RUN apt-get update -qq && apt-get install -y build-essential libpq-dev nodejs

#yarn package management tool installation
RUN apt-get update && apt-get install -y curl apt-transport-https wget && \
curl -sS https://dl.yarnpkg.com/debian/pubkey.gpg | apt-key add - && \
echo "deb https://dl.yarnpkg.com/debian/ stable main" | tee /etc/apt/sources.list.d/yarn.list && \
apt-get update && apt-get install -y yarn

#Work directory settings
RUN mkdir /myapp
WORKDIR /myapp
ADD Gemfile /myapp/Gemfile
ADD Gemfile.lock /myapp/Gemfile.lock
RUN bundle install
COPY . /myapp
EXPOSE  3000

Added host, ʻusername, and passwrdsettings todatabase.yml`

/config/database.yml

:abridgement

default: &default
  adapter: postgresql
  encoding: unicode
  host: <%= ENV.fetch("DATABASE_HOST") { "127.0.0.1" } %>               #Postscript
  username: <%= ENV.fetch("DATABASE_USER") { "postgres" } %>            #Postscript
  password: <%= ENV.fetch("DATABASE_PASSWORD") { "" } %>                #Postscript
  # For details on connection pooling, see Rails configuration guide
  # https://guides.rubyonrails.org/configuring.html#database-pooling
  pool: <%= ENV.fetch("RAILS_MAX_THREADS") { 5 } %>

:abridgement

image construction

$ docker-compose build

Package installation

$ docker-compose run --rm web bin/yarn install

Database creation

$ docker-compose run --rm web rails db:create

Start-up

$ docker-compose up

You can access http: // localhost: 3000 /.

When moving directly locally

Edit .env and launch it with yarn install, rails db: create, rails s.