A simple Rails application in one Docker container

simple_rails_container.md

A simple Rails application in one Docker container

This Gist helps to build and start a simple Rails application in a single Docker container (no docker-compose needed).

1. Go to your projects folder

cd /home/user/my_projects

2. Run a temporary ruby:2.x container that will install Rails

docker run --rm -v "${PWD}":/application -w /application  ruby:2.7 /bin/bash -c "gem install rails -v '6.1' && rails new simple_rails_app_container --minimal ."

3. Change the newly created folder's permissions to match the current user

sudo chown -R ${USER:=$(/usr/bin/id -run)}:$USER simple_rails_app_container

4. Enter the newly created folder

cd /home/user/my_projects/simple_rails_app_container

5. Create a Dockerfile with this content

FROM ruby:2.7

RUN apt-get update -qq && \
    apt-get install -y nodejs && \
    apt-get clean && \
    bundle config --global frozen 1

WORKDIR /application

COPY Gemfile Gemfile.lock ./
RUN bundle install

COPY . .

EXPOSE 3000

# Configure the main process to run when running the image
CMD ["rails", "server", "-b", "0.0.0.0"]

6. Build the custom image

docker build -t simple_rails_app_container:1.0 . 

7. Run it

docker run --name simple_rails_app_container-1 -v "${PWD}":/application -p3000:3000 simple_rails_app_container:1.0

8. Try it in your browser: http://0.0.0.0:3000