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300 lines
6.5 KiB
Go
300 lines
6.5 KiB
Go
## 10.7 使用 Rails
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> 本小节内容适合 Ruby 开发人员阅读。
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本节使用 Docker Compose 配置并运行一个 **Rails + PostgreSQL** 应用。
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### 10.7.1 架构概览
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如图 10-2 所示,Rails 与 PostgreSQL 在同一 Compose 网络中协同工作。
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```mermaid
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flowchart TD
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subgraph Network ["Docker Compose 网络"]
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direction LR
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subgraph Web ["web 服务"]
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direction TB
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Rails["Rails<br/>应用"]
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Port3000[":3000"]
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Rails ~~~ Port3000
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end
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subgraph DB ["db 服务"]
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direction TB
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Postgres["PostgreSQL<br/>数据库"]
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end
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Rails -- ":5432" --> Postgres
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end
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Browser["localhost:3000"]
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Port3000 --> Browser
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```
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图 10-2 Rails + PostgreSQL 的 Compose 架构
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### 10.7.2 准备工作
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创建项目目录:
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```bash
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$ mkdir rails-docker && cd rails-docker
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```
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需要创建三个文件:`Dockerfile`、`Gemfile` 和 `compose.yaml`。
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### 10.7.3 步骤 1:创建 Dockerfile
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如下代码块所示,展示了相关示例:
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```docker
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FROM ruby:3.2
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## 安装系统依赖
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RUN apt-get update -qq && \
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apt-get install -y build-essential libpq-dev nodejs && \
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rm -rf /var/lib/apt/lists/*
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## 设置工作目录
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WORKDIR /myapp
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## 先复制 Gemfile,利用缓存加速构建
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COPY Gemfile /myapp/Gemfile
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COPY Gemfile.lock /myapp/Gemfile.lock
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RUN bundle install
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## 复制应用代码
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COPY . /myapp
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```
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**配置说明**:
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| 指令 | 作用 |
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|------|------|
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| `build-essential` | 编译原生扩展所需 |
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| `libpq-dev` | PostgreSQL 客户端库 |
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| `nodejs` | Rails Asset Pipeline 需要 |
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| 先复制 Gemfile | 只有依赖变化时才重新 `bundle install` |
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### 10.7.4 步骤 2:创建 Gemfile
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创建一个初始的 `Gemfile`,稍后会被 `rails new` 覆盖:
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```ruby
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source 'https://rubygems.org'
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gem 'rails', '~> 7.1'
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```
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创建空的 `Gemfile.lock`:
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```bash
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$ touch Gemfile.lock
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```
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### 10.7.5 步骤 3:创建 compose.yaml
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配置如下:
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```yaml
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services:
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db:
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image: postgres:16
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environment:
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POSTGRES_PASSWORD: password
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volumes:
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- postgres_data:/var/lib/postgresql/data
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web:
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build: .
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command: bash -c "rm -f tmp/pids/server.pid && bundle exec rails s -p 3000 -b '0.0.0.0'"
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volumes:
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- .:/myapp
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ports:
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- "3000:3000"
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depends_on:
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- db
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environment:
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DATABASE_URL: postgres://postgres:password@db:5432/myapp_development
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volumes:
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postgres_data:
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```
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**配置详解**:
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| 配置项 | 说明 |
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|--------|------|
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| `rm -f tmp/pids/server.pid` | 清理上次异常退出留下的 PID 文件 |
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| `volumes: .:/myapp` | 挂载代码目录,支持热更新 |
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| `depends_on: db` | 确保数据库先启动 |
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| `DATABASE_URL` | Rails 12-factor 风格的数据库配置 |
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### 10.7.6 步骤 4:生成 Rails 项目
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使用 `docker compose run` 生成项目骨架:
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```bash
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$ docker compose run --rm web rails new . --force --database=postgresql --skip-bundle
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```
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**命令解释**:
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- `--rm`:执行后删除临时容器
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- `--force`:覆盖已存在的文件
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- `--database=postgresql`:配置使用 PostgreSQL
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- `--skip-bundle`:暂不安装依赖 (稍后统一安装)
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生成的目录结构:
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```bash
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$ ls
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Dockerfile Gemfile Rakefile config lib tmp
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Gemfile.lock README.md app config.ru log vendor
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compose.yaml bin db public
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```
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> ⚠️ **Linux 用户**:如遇权限问题,执行 `sudo chown -R $USER:$USER .`
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### 10.7.7 步骤 5:重新构建镜像
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由于生成了新的 Gemfile,需要重新构建镜像以安装完整依赖:
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```bash
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$ docker compose build
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```
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### 10.7.8 步骤 6:配置数据库连接
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修改 `config/database.yml`:
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```yaml
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default: &default
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adapter: postgresql
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encoding: unicode
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pool: <%= ENV.fetch("RAILS_MAX_THREADS") { 5 } %>
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url: <%= ENV['DATABASE_URL'] %>
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development:
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<<: *default
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test:
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<<: *default
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database: myapp_test
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production:
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<<: *default
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```
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> 💡 使用 `DATABASE_URL` 环境变量配置数据库,符合 12-factor 应用原则,便于在不同环境间切换。
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### 10.7.9 步骤 7:启动应用
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运行以下命令:
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```bash
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$ docker compose up
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```
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输出示例:
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```bash
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db-1 | PostgreSQL init process complete; ready for start up.
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db-1 | LOG: database system is ready to accept connections
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web-1 | => Booting Puma
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web-1 | => Rails 7.1.0 application starting in development
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web-1 | => Run `bin/rails server --help` for more startup options
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web-1 | Puma starting in single mode...
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web-1 | * Listening on http://0.0.0.0:3000
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```
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### 10.7.10 步骤 8:创建数据库
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在另一个终端执行:
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```bash
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$ docker compose exec web rails db:create
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Created database 'myapp_development'
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Created database 'myapp_test'
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```
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访问 http://localhost:3000 查看 Rails 欢迎页面。
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### 10.7.11 常用开发命令
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运行以下命令:
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```bash
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## 数据库迁移
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$ docker compose exec web rails db:migrate
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## Rails 控制台
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$ docker compose exec web rails console
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## 运行测试
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$ docker compose exec web rails test
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## 生成脚手架
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$ docker compose exec web rails generate scaffold Post title:string body:text
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## 进入容器 Shell
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$ docker compose exec web bash
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```
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### 10.7.12 常见问题
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本节涵盖了相关内容与详细描述,主要探讨以下几个方面:
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#### Q:数据库连接失败
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检查 `DATABASE_URL` 环境变量格式是否正确,确保 db 服务已启动:
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```bash
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$ docker compose ps
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$ docker compose logs db
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```
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#### Q:server.pid 文件导致启动失败
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错误信息:`A server is already running`
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已在 command 中添加 `rm -f tmp/pids/server.pid` 处理。如仍有问题:
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```bash
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$ docker compose exec web rm -f tmp/pids/server.pid
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```
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#### Q:Gem 安装失败
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可能需要更新 bundler 或清理缓存:
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```bash
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$ docker compose run --rm web bundle update
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```
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### 10.7.13 开发 vs 生产
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相关信息如下表:
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| 配置项 | 开发环境 | 生产环境 |
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|--------|---------|---------|
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| Rails 服务器 | Puma (开发模式) | Puma + Nginx |
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| 代码挂载 | 使用 volumes | 代码打包进镜像 |
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| 静态资源 | 动态编译 | 预编译 (`rails assets:precompile`) |
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| 数据库密码 | 明文配置 | 使用 Secrets 管理 |
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### 10.7.14 延伸阅读
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- [使用 Django](10.6_django.md):Python Web 框架实战
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- [Compose 模板文件](10.5_compose_file.md):配置详解
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- [数据管理](../08_data_network/README.md):数据持久化
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