Docker部署Rails 6应用：Nginx加载静态资源报404错误

生产环境下，Docker部署的Rails 6应用中Nginx加载静态资源全部返回404，但文件系统中资源确实存在，其他文件可正常加载。以下是相关配置文件及解决方案：

Dockerfile #

FROM ruby:2.6.1

RUN curl https://deb.nodesource.com/setup_12.x | bash
RUN curl https://dl.yarnpkg.com/debian/pubkey.gpg | apt-key add -
RUN echo "deb https://dl.yarnpkg.com/debian/ stable main" | tee /etc/apt/sources.list.d/yarn.list

RUN apt-get update && apt-get install -y nodejs yarn

WORKDIR /my_app

RUN export RAILS_ENV=production

RUN gem install bundler:2.2.31

COPY Gemfile Gemfile.lock ./
COPY package.json ./

COPY vendor/gems/ vendor/gems/

RUN bundle install

COPY . ./

RUN yarn install --check-files

RUN RAILS_ENV=production bundle exec rake assets:precompile SECRET_KEY_BASE=1

EXPOSE 3000

CMD ["RAILS_ENV=production", "bundle", "exec", "puma", "-C", "config/puma.rb"]

docker-compose.yml #

version: '3'

services:

  database:
    image: mysql:5.7
    restart: always
    container_name: database
    environment:
      MYSQL_DATABASE: my_app_production
      MYSQL_USER: my_app
      MYSQL_PASSWORD: my_app_password
      MYSQL_RANDOM_ROOT_PASSWORD: "yes"
    ports:
      - "3306:3306"
    volumes:
      - dbdata:/var/lib/mysql

  my_app:
    image: my_app
    container_name: my_app
    volumes:
      - ./public:/my_app/public
      - ./public/assets:/my_app/public/assets
      - tmp:/my_app/tmp
      - yarn_cache:/var/www/.cache/yarn
    command: bash -c "sleep 5 && bundle exec rails db:migrate && bundle exec puma -C config/puma.rb"
    environment:
      RAILS_ENV: production
      SECRET_KEY_BASE: xxxxxxx
      DATABASE_PASSWORD: my_app_password
    ports:
      - "3000:3000"
    depends_on:
      - database
    links:
      - database

  webserver:
    image: nginx:latest
    ports:
      - 80:80
    restart: always
    volumes:
      - ./nginx/conf/:/etc/nginx/conf.d/:ro

volumes:
 dbdata:
 tmp:
 yarn_cache:

nginx.conf #

upstream my_app {
    server my_app:3000;
}

server {
    server_name my.domain.name;

    root /my_app/public;

    try_files $uri/index.html $uri @rails;

    location ~ ^/(assets|packs)/{
        try_files $uri @rails;
        access_log off;
        gzip_static on;
        expires max;
        add_header Cache-Control public;
        add_header Last-Modified "";
        add_header ETag "";
        break;
    }

    location @rails {
        proxy_pass http://my_app;

        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header Host $http_host;
        proxy_set_header X-Forwarded-Proto https;
        proxy_redirect off;

        proxy_connect_timeout 4m;
        proxy_read_timeout    4m;
        proxy_send_timeout    4m;
    }

    error_page 500 502 503 504 /500.html;
    client_max_body_size 4G;
    keepalive_timeout 10;

    listen 80;
}

问题分析与解决方案 #

1. Nginx容器无法访问静态资源路径

Nginx配置中root /my_app/public，但Nginx容器内不存在该路径，需将Rails应用的静态资源目录挂载到Nginx容器。修改docker-compose.yml的webserver服务：

webserver:
  image: nginx:latest
  ports:
    - 80:80
  restart: always
  volumes:
    - ./nginx/conf/:/etc/nginx/conf.d/:ro
    - ./public:/my_app/public  # 挂载本地public目录到Nginx容器内对应路径

2. 本地卷覆盖镜像内预编译资源

Dockerfile已完成assets:precompile，但docker-compose.yml中挂载的./public和./public/assets会覆盖镜像内的预编译资源。若本地目录为空或不一致，就会导致Nginx找不到资源。移除这两个挂载卷：

my_app:
  image: my_app
  container_name: my_app
  volumes:
    # 移除以下两行
    # - ./public:/my_app/public
    # - ./public/assets:/my_app/public/assets
    - tmp:/my_app/tmp
    - yarn_cache:/var/www/.cache/yarn
  # 其余配置不变

3. Nginx静态资源处理逻辑错误

当前location ~ ^/(assets|packs)/中，找不到文件会转发给Rails，但生产环境Rails默认不处理静态资源，导致404。修改Nginx配置，让Nginx直接处理静态资源：

location ~ ^/(assets|packs)/ {
    try_files $uri =404;  # 找不到直接返回404，不转发
    access_log off;
    gzip_static on;
    expires max;
    add_header Cache-Control public;
    add_header Last-Modified "";
    add_header ETag "";
}

4. 确认Rails生产环境配置

确保config/environments/production.rb中config.public_file_server.enabled = false（默认值），让Nginx全权处理静态资源，避免Rails介入。

内容的提问来源于stack exchange，提问作者Simon Mo