How to set up a Rails development environment with Docker

· 3 min read

Getting a Rails application’s codebase running shouldn’t be difficult. Yet developers spend hours troubleshooting environment issues. Docker solves this.

Why Docker for Development?

  • Consistent environments - Works the same on every machine
  • Easy onboarding - New devs run one command
  • Isolated dependencies - No conflicts with other projects
  • Production parity - Develop in an environment similar to production (pair this with deployment tracking via Rails.app.revision to know exactly which code is running)

Basic Setup

Create a Dockerfile:

FROM ruby:3.2

RUN apt-get update -qq && apt-get install -y nodejs postgresql-client

WORKDIR /app

COPY Gemfile Gemfile.lock ./
RUN bundle install

COPY . .

CMD ["rails", "server", "-b", "0.0.0.0"]

Create a docker-compose.yml:

version: '3.8'

services:
  db:
    image: postgres:15
    environment:
      POSTGRES_PASSWORD: password
    volumes:
      - postgres_data:/var/lib/postgresql/data

  web:
    build: .
    command: bash -c "rm -f tmp/pids/server.pid && rails server -b 0.0.0.0"
    volumes:
      - .:/app
    ports:
      - "3000:3000"
    depends_on:
      - db
    environment:
      DATABASE_URL: postgres://postgres:password@db/app_development

volumes:
  postgres_data:

Running Your App

docker compose build
docker compose up

Visit http://localhost:3000 and you’re ready to develop.

Tips

  • Use volume mounts for live code reloading
  • Add Redis, Sidekiq as needed
  • Create a bin/docker-dev script for common commands

Docker removes the “it works on my machine” problem and lets your team focus on building features. Once your containerized environment is running, keep an eye on version-specific behavior like the connection pool changes introduced in Rails 7.2 that can affect performance.