├── Dockerfile
├── Gemfile
├── Gemfile.lock
├── README.md
└── docker-compose.yml


/Dockerfile:
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 1 | FROM ruby:2.4.2
 2 | 
 3 | ENV APP_ROOT /app
 4 | ENV BUNDLE_PATH /usr/local/bundle
 5 | 
 6 | RUN apt-get update -qq && \
 7 |     apt-get install -y build-essential libpq-dev nodejs
 8 | 
 9 | WORKDIR $APP_ROOT
10 | ADD . $APP_ROOT
11 | 


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/Gemfile:
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1 | source 'https://rubygems.org'
2 | 
3 | gem 'rails', '~> 5'
4 | 


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/Gemfile.lock:
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https://raw.githubusercontent.com/lucatironi/rails-docker/4f8ed8c72854c360424c4edb700dd9dfdf628e87/Gemfile.lock


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/README.md:
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  1 | # Setup, Build and Run a Rails 5 web application with Docker and Docker Compose
  2 | 
  3 | ## Setup the project
  4 | 
  5 | In order to kickstart the application we need to install the rails gem and run the
  6 | `rails new <appname>` command. We will do this inside the same Docker container
  7 | that will be used to run the application itself. To do so we need to create a
  8 | `Dockerfile` to create the Docker image with the necessary dependencies, a
  9 | `docker-compose.yml` file to provision the other services needed (a postgres
 10 | database and a volume store) and a `Gemfile` (with an empty `Gemfile.lock`) to
 11 | install the `rails` gem and bundle install its dependencies.
 12 | 
 13 | Create a new directory and some empty files:
 14 | 
 15 | ```
 16 | $ mkdir rails-docker
 17 | $ cd rails-docker
 18 | $ touch Dockerfile docker-compose.yml Gemfile Gemfile.lock
 19 | ```
 20 | 
 21 | Copy and paste the following content in the respective files:
 22 | 
 23 | File: `Dockerfile`
 24 | 
 25 | ```
 26 | FROM ruby:2.4.2
 27 | 
 28 | ENV APP_ROOT /app
 29 | ENV BUNDLE_PATH /usr/local/bundle
 30 | 
 31 | RUN apt-get update -qq && \
 32 |     apt-get install -y build-essential libpq-dev nodejs
 33 | 
 34 | WORKDIR $APP_ROOT
 35 | ADD . $APP_ROOT
 36 | ```
 37 | 
 38 | File: `docker-compose.yml`
 39 | 
 40 | ```
 41 | version: '3'
 42 | 
 43 | volumes:
 44 |   store:
 45 |     driver: local
 46 |   bundle:
 47 |     driver: local
 48 | 
 49 | services:
 50 |   web:
 51 |     build: .
 52 |     ports:
 53 |       - 3000:3000
 54 |     volumes:
 55 |       - .:/app
 56 |       - bundle:/usr/local/bundle
 57 |     links:
 58 |       - db
 59 |     # Keep the stdin open, so we can attach to our app container's process and do things such as
 60 |     # byebug, etc:
 61 |     stdin_open: true
 62 |     # Enable sending signals (CTRL+C, CTRL+P + CTRL+Q) into the container:
 63 |     tty: true
 64 |     command: ./bin/start.sh
 65 |     environment: &app_env
 66 |       PORT: 3000
 67 |       DB_HOST: db
 68 |       DB_PORT: 5432
 69 |       DB_USER: postgres
 70 |       DB_PSWD: postgres
 71 |       DB_NAME: development_database
 72 |   db:
 73 |     image: postgres:latest
 74 |     ports:
 75 |       - 5432:5432
 76 |     volumes:
 77 |       - store:/var/lib/postgresql/data
 78 |     environment:
 79 |       POSTGRES_USER: postgres
 80 |       POSTGRES_PASSWORD: postgres
 81 |       POSTGRES_DB: development_database
 82 | ```
 83 | 
 84 | File: `Gemfile`
 85 | 
 86 | ```
 87 | source 'https://rubygems.org'
 88 | 
 89 | gem 'rails', '~> 5'
 90 | ```
 91 | 
 92 | ## Build the project
 93 | 
 94 | First we need to bundle the rails 5 dependencies:
 95 | 
 96 | ```
 97 | $ docker-compose run --rm web bundle --jobs=10 --retry=5
 98 | ```
 99 | 
100 | And then use the `rails new` command to create the new application:
101 | 
102 | ```
103 | $ docker-compose run --rm web bundle exec rails new . --force --database=postgresql --skip-bundle
104 | ```
105 | 
106 | ## Configure the database
107 | 
108 | We need to change slightly the database configuration to use the environment
109 | variables set in the docker-compose file:
110 | 
111 | File: `config/database.yml`
112 | 
113 | ```
114 | default: &default
115 |   adapter: postgresql
116 |   encoding: unicode
117 |   username: <%= ENV['DB_USER'] %>
118 |   password: <%= ENV['DB_PSWD'] %>
119 |   host: <%= ENV['DB_HOST'] %>
120 |   # For details on connection pooling, see rails configuration guide
121 |   # http://guides.rubyonrails.org/configuring.html#database-pooling
122 |   pool: <%= ENV.fetch("RAILS_MAX_THREADS") { 5 } %>
123 | 
124 | development:
125 |   <<: *default
126 |   database: <%= ENV['DB_NAME'] %>
127 | 
128 | test:
129 |   <<: *default
130 |   database: test_database
131 | ```
132 | 
133 | ## Setup the app
134 | 
135 | ```
136 | $ docker-compose run --rm web bin/setup
137 | ```
138 | 
139 | Create a `start.sh` file in the `bin` dir:
140 | 
141 | File: `bin/start.sh`
142 | 
143 | ```
144 | #!/bin/bash
145 | 
146 | bundle check || bundle install
147 | 
148 | if [ -f tmp/pids/server.pid ]; then
149 |   rm -f tmp/pids/server.pid
150 | fi
151 | 
152 | bundle exec rails s -p $PORT -b 0.0.0.0
153 | ```
154 | 
155 | It automatically removes the `server.pid` that will create problems when you stop
156 | and restart the app.
157 | Make the file executable with the `chmod` command:
158 | 
159 | ```
160 | $ chmod +x bin/start.sh
161 | ```
162 | 
163 | Finally start your newly created Rails application and visit [localhost:3000](http://localhost:3000):
164 | 
165 | ```
166 | $ docker-compose up
167 | ```
168 | 


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/docker-compose.yml:
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 1 | version: '3'
 2 | 
 3 | volumes:
 4 |   store:
 5 |     driver: local
 6 |   bundle:
 7 |     driver: local
 8 | 
 9 | services:
10 |   web:
11 |     build: .
12 |     ports:
13 |       - 3000:3000
14 |     volumes:
15 |       - .:/app
16 |       - bundle:/usr/local/bundle
17 |     links:
18 |       - db
19 |     # Keep the stdin open, so we can attach to our app container's process and do things such as
20 |     # byebug, etc:
21 |     stdin_open: true
22 |     # Enable sending signals (CTRL+C, CTRL+P + CTRL+Q) into the container:
23 |     tty: true
24 |     command: ./bin/start.sh
25 |     environment: &app_env
26 |       PORT: 3000
27 |       DB_HOST: db
28 |       DB_PORT: 5432
29 |       DB_USER: postgres
30 |       DB_PSWD: postgres
31 |       DB_NAME: development_database
32 |   db:
33 |     image: postgres:latest
34 |     ports:
35 |       - 5432:5432
36 |     volumes:
37 |       - store:/var/lib/postgresql/data
38 |     environment:
39 |       POSTGRES_USER: postgres
40 |       POSTGRES_PASSWORD: postgres
41 |       POSTGRES_DB: development_database
42 | 


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