rails 7 first step

docker-compose.yml

version: '3'
services:
  app:
    build: .
    command: bundle exec rails s -p 3000 -b '0.0.0.0'
    volumes:
      - .:/app
    ports:
      - "3000:3000"
    volumes:
      - .:/app
      - bundle_app:/usr/local/bundle:cached

volumes:
  bundle_app:
    driver: local

Dockerfile

FROM ruby:3
RUN mkdir /app
WORKDIR /app
ADD Gemfile /app/Gemfile
ADD Gemfile.lock /app/Gemfile.lock
RUN bundle install
ADD . /app

Gemfile

# frozen_string_literal: true

source "https://rubygems.org"

gem "rails", "~> 7.0"