local environment(mysql + postgres + adminer)

docker-compose.yml

version: '3.1'

services:
  mysql-db:
    image: mysql:8.1.0
    # NOTE: use of "mysql_native_password" is not recommended: https://dev.mysql.com/doc/refman/8.0/en/upgrading-from-previous-series.html#upgrade-caching-sha2-password
    # (this is just an example, not intended to be a production configuration)
    command: --default-authentication-plugin=mysql_native_password
    restart: always
    environment:
      MYSQL_ROOT_PASSWORD: password
    ports:
      - 3306:3306
    volumes:
      - mysql:/var/lib/mysql

  postgres-db:
    build: ./postgres
    restart: always
    environment:
      POSTGRES_PASSWORD: password
      POSTGRES_INITDB_ARGS: "--locale ja_JP.UTF-8"
    ports:
      - 5432:5432
    volumes:
      - postgres:/var/lib/postgresql/data

  adminer:
    image: adminer
    restart: always
    ports:
      - 8080:8080

  ruby-app:
    build: ./ruby_app
    volumes:
      - ./ruby_app:/app
      - bundle_data:/usr/local/bundle
    depends_on:
      - mysql-db
      - postgres-db

volumes:
  mysql:
  postgres:
  bundle_data:

gistfile1.txt

 % find .
.
./postgres
./postgres/Dockerfile
./ruby_app
./ruby_app/Dockerfile
./docker-compose.yml

postgres Dockerfile

# https://hub.docker.com/_/postgres/
FROM postgres:16.0

RUN apt-get update && apt-get install -y locales && \
    sed -i -e 's/# ja_JP.UTF-8 UTF-8/ja_JP.UTF-8 UTF-8/' /etc/locale.gen && \
    locale-gen

ENV LANG ja_JP.utf8

ruby_app Dockerfile

FROM ruby:3.2.2-slim-bullseye

# active_record の動作する最低限をインストール
RUN apt-get update -qq && apt-get install -y \
    sqlite3 libsqlite3-dev \
    build-essential \
    vim \
    locales \
    libpq-dev \
    postgresql-client \
    default-libmysqlclient-dev \
    default-mysql-client
RUN gem install bundler

RUN sed -i -E 's/# (ja_JP.UTF-8)/\1/' /etc/locale.gen && locale-gen
ENV LANG ja_JP.UTF-8

WORKDIR /app

COPY . .