base rails docker config: only a dockerfile and a docker-compose.yml (with a makefile ;-)) Notice the app_name and application_name must be adapted to your app.

.env.local

DATABASE_HOST=app_name-db
DATABASE_USER=postgres
DATABASE_PASSWORD=password

docker-compose.yml

version: '3'

services:

  app_name-db:
    image: postgres:latest
    ports:
      - "5434:5432"
    volumes:
      - postgres-data:/var/lib/postgresql/data
    env_file: 
      - .env.local
    environment:
      - POSTGRES_HOST_AUTH_METHOD=trust

  app_name-web:
    build: .
    command: bash -c "rm -f tmp/pids/server.pid && bundle exec rails s -p 3000 -b '0.0.0.0'"
    volumes:
      - .:/app_name
      - bundle-path:/bundle
    env_file: 
      - .env.local
    environment:
      - BUNDLE_PATH=/bundle/vendor
    ports:
      - "3001:3000"
    depends_on:
      - app_name-db
  
volumes:
  postgres-data: 
    driver: local
  bundle-path:
    driver: local

Dockerfile

FROM docker.io/library/ruby:3.1.2-buster AS app_builder

RUN apt-get update -qq && \
  apt-get install -y --no-install-recommends nodejs build-essential libpq-dev graphviz && \
  rm -rf /var/lib/apt/lists/*

FROM app_builder AS app_runner

RUN mkdir /app_name
WORKDIR /app_name

COPY Gemfile* ./

RUN gem install bundler
RUN bundle install

COPY . .

Makefile

APPLICATION_NAME = app_name
WEB_CONTAINER_NAME = $(APPLICATION_NAME)-web
.DEFAULT_GOAL := help

CONTAINER_APP_MANAGER = docker ## Podman vs Docker

# Docker stuff
attach: ## Attach running web container to see logs
	$(CONTAINER_APP_MANAGER) attach $(APPLICATION_NAME)_$(WEB_CONTAINER_NAME)_1

up: ## Run containers
	$(CONTAINER_APP_MANAGER) compose up -d

down: ## Stop containers
	$(CONTAINER_APP_MANAGER) compose down

serve: up ## Run Serve
	make attach

ps: ## List containers
	$(CONTAINER_APP_MANAGER) compose ps

restart_web: ## Restart Web container
	$(CONTAINER_APP_MANAGER) compose restart $(WEB_CONTAINER_NAME)

# Build containers
build: ## Build containers
	$(CONTAINER_APP_MANAGER) compose build

clean: down ## Cleanup docker images.
	$(CONTAINER_APP_MANAGER) system prune -a

rebuild: clean ## Stop containers, delete docker images not used and build container
	make build

# Rails install tools
bundle: ## Run bundle install
	$(CONTAINER_APP_MANAGER) compose run --rm $(WEB_CONTAINER_NAME) bundle install

migrate: ## Run rake db migrate
	$(CONTAINER_APP_MANAGER) compose run --rm $(WEB_CONTAINER_NAME) bundle exec rake db:migrate

init_db: ## drop, create and migrate DB (Data will be lost)
	$(CONTAINER_APP_MANAGER) compose run --rm $(WEB_CONTAINER_NAME) bundle exec rake db:drop db:create db:migrate

# Devs console
bash: ## Run bash in web-container
	$(CONTAINER_APP_MANAGER) compose run --rm $(WEB_CONTAINER_NAME) bash

console: ## Run Rails console
	$(CONTAINER_APP_MANAGER) compose run --rm $(WEB_CONTAINER_NAME) bundle exec rails c

# Code smells tools
sniff: ## Run code smelling tools (rubocop, reek, brakeman and fasterer only for now)
	- make rubocop
	- make reek

rubocop: ## Run project rubocop
	$(CONTAINER_APP_MANAGER) compose run --rm $(WEB_CONTAINER_NAME) bundle exec rubocop .

reek: ## Run project reek
	$(CONTAINER_APP_MANAGER) compose run --rm $(WEB_CONTAINER_NAME) bundle exec reek .

brakeman: ## Run project brakeman
	$(CONTAINER_APP_MANAGER) compose run --rm $(WEB_CONTAINER_NAME) bundle exec brakeman .

fasterer: ## Run project fasterer
	$(CONTAINER_APP_MANAGER) compose run --rm $(WEB_CONTAINER_NAME) bundle exec fasterer .

# tests
tests: ## Run test locally in web container (with failfast and code coverage option)
	$(CONTAINER_APP_MANAGER) compose run -e COVERAGE=true --rm $(WEB_CONTAINER_NAME) bundle exec rspec .

# Other things
.PHONY: help

help:
	@grep -E '^[a-zA-Z_-]+:.*?## .*$$' $(MAKEFILE_LIST) | sort | awk 'BEGIN {FS = ":.*?## "}; {printf "\033[36m%-30s\033[0m %s\n", $$1, $$2}'