【Docker】RailsにNginxを導入する方法

## はじめに
　本記事は、プログラミング初学者、学習を進めていて疑問に思った点について調べた結果を備忘録も兼ねてまとめたものです。
　そのため、記事の内容に誤りが含まれている可能性があります。ご容赦ください。
　間違いを見つけた方は、お手数ですが、ご指摘いただけますと幸いです。

## Nginx + Puma + Rails + MySQL
Dokerfileで親ディレクトリを参照するにはDocker-composeのbuildの箇所でcontextとdockerfileを指定します。

```docker-compose.yml
version: '${COMPOSE_VER}'
services:
  db:
    platform: linux/x86_64
    build: ./docker/db
    command: --default-authentication-plugin=mysql_native_password && bash -c "chmod +x /docker-entrypoint-initdb.d/00_grant.sh"
    healthcheck:
      test: mysqladmin ping -h db -u$${MYSQL_USER} -p$${MYSQL_PASSWORD}
      interval: 1s
    restart: on-failure
    volumes:
      - mysql_data:/var/lib/mysql
      - type: bind
        source: ${MY_CNF_PATH}
        target: /etc/mysql/conf.d/my.cnf
      - type: bind
        source: ${INITDB_PATH}
        target: /docker-entrypoint-initdb.d
    env_file:
      - ${DB_ENV_FILE_PATH}
    ports:
      - "${DB_PORT}:3306"
  api:
    build:
      context: .
      dockerfile: ./docker/api/Dockerfile
    command: bash -c "rm -f tmp/pids/server.pid && bundle exec rails s -p 3000 -b '0.0.0.0'"
    restart: on-failure
    volumes:
      - .:/myapp
      - public-data:/myapp/public
      - tmp-data:/myapp/tmp
    environment:
      RAILS_ENV: ${APP_ENV}
    ports:
      - "${API_PORT}:3000"
    depends_on:
      db:
        condition: service_healthy
  web:
    build: ./docker/web
    volumes:
      - public-data:/myapp/public
      - tmp-data:/myapp/tmp
    ports:
      - 80:80
    depends_on:
      - api
volumes:
  mysql_data:
  public-data:
  tmp-data:
```

```Dockerfile:Dockerfile(Nginx)
FROM nginx:alpine

RUN rm -f /etc/nginx/conf.d/*

ADD nginx.conf /etc/nginx/conf.d/myapp.conf

CMD /usr/sbin/nginx -g 'daemon off;' -c /etc/nginx/nginx.conf

```

```nginx.conf
upstream myapp {
  server unix:///myapp/tmp/sockets/puma.sock;
}

server {
  listen 80;
  server_name localhost;
  access_log /var/log/nginx/access.log;
  error_log  /var/log/nginx/error.log;

  root /myapp/public;

  client_max_body_size 100m;
  error_page 404             /404.html;
  error_page 505 502 503 504 /500.html;
  try_files  $uri/index.html $uri @myapp;
  keepalive_timeout 5;

  location @myapp {
    proxy_set_header X-Real-IP $remote_addr;
    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    proxy_set_header Host $http_host;
    proxy_pass http://myapp;
  }
}

```

```Dockerfile:Dockerfile(Rails)
FROM ruby:3.1.1
ENV APP_NAME=myapp
ENV USER_NAME=myuser
ENV TZ=Asia/Tokyo

WORKDIR /${APP_NAME}

COPY Gemfile /${APP_NAME}/Gemfile
COPY Gemfile.lock  /${APP_NAME}/Gemfile.lock
RUN bundle install

COPY /docker/api/entrypoint.sh /usr/bin/
RUN chmod +x /usr/bin/entrypoint.sh
ENTRYPOINT ["entrypoint.sh"]

RUN adduser ${USER_NAME} && \
    chown -R ${USER_NAME} /${APP_NAME} && \
    chown -R ${USER_NAME} ${GEM_HOME}
USER ${USER_NAME}

EXPOSE 3000

CMD ["rails", "server", "-b", "0.0.0.0"]
```
```:Gemfile
source "https://rubygems.org"

gem "rails", "~> 7.0.2", ">= 7.0.2.3"
```
```puma.rb
threads_count = ENV.fetch("RAILS_MAX_THREADS") { 5 }
threads threads_count, threads_count
port        ENV.fetch("API_PORT") { 3000 }
environment ENV.fetch("RAILS_ENV") { "development" }
plugin :tmp_restart

app_root = File.expand_path("../..", __FILE__)
bind "unix://#{Rails.root}/tmp/sockets/puma.sock"

stdout_redirect "#{app_root}/log/puma.stdout.log", "#{app_root}/log/puma.stderr.log", true
```