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Spring Boot 4 Microservices & REST APIs · 课时

使用 Docker Compose 管理容器

使用 Docker Compose 编排微服务所需的多个 Docker 容器。

第 2 / 3 课11 个步骤

使用 Docker Compose 管理容器 是 CoddyKit 上的免费 Spring Boot 4 Microservices & REST APIs 课时。 这是第 2 节课，共 3 节。 你可以在下方免费阅读本课时的完整内容 — 然后在浏览器中使用内置代码编辑器和全天候 AI 导师进行实践。 这是 Spring Boot 4 Microservices & REST APIs 学习路径的一部分，你的进度在网页和 CoddyKit 应用中同步。 Spring Boot 4 Microservices & REST APIs 课程共包含 3 节课。

本课时的部分内容尚未翻译，以英文显示。

Why Multi-Container Apps?

Microservices often rely on several components. Think of a Spring Boot application needing a database, a message queue, or another API service.

Each component typically runs in its own Docker container. Managing these individually can become complex, especially during development.

How do we start them all together, ensure they can communicate, and manage their lifecycle efficiently? This is where Docker Compose steps in!

Introducing Docker Compose

Docker Compose is a tool for defining and running multi-container Docker applications. Instead of managing each container separately, you define all services in a single, easy-to-read file.

This definition file is typically named docker-compose.yml. It uses YAML syntax, which is both human-readable and machine-parseable.

Compose simplifies your development workflow by letting you spin up your entire application stack with a single command.

Basic docker-compose.yml Structure

The docker-compose.yml file starts with a version, followed by the services section where you define each container as a distinct service.

Each service represents a container, and you can specify its image, exposed ports, environment variables, and more.

Here's a minimal structure for a simple web app:

version: '3.8'
services:
  webapp:
    image: 'nginx:latest'
    ports:
      - '80:80'

Defining a Web Service

Let's define a simple web service. We'll use the official Nginx image, map a port, and give it an optional container_name.

The image key specifies the Docker image to use (e.g., nginx:latest). The ports key maps host ports to container ports (e.g., host's port 80 to container's port 80).

version: '3.8'
services:
  webapp:
    image: 'nginx:latest'
    ports:
      - '80:80'
    container_name: my_nginx_app

Adding a Database Service

Most applications need a database. Let's add a PostgreSQL database service to our docker-compose.yml file.

We'll specify the postgres:13 image and set crucial environment variables for credentials (POSTGRES_DB, POSTGRES_USER, POSTGRES_PASSWORD).

version: '3.8'
services:
  webapp:
    image: 'nginx:latest'
    ports:
      - '80:80'
  database:
    image: 'postgres:13'
    environment:
      POSTGRES_DB: mydatabase
      POSTGRES_USER: user
      POSTGRES_PASSWORD: password

Connecting Services (Networking)

Docker Compose automatically creates a default network for all services defined in your docker-compose.yml file.

Services can communicate with each other using their service names as hostnames. For example, your web app can connect to the database using database as the hostname and the specified port (e.g., 5432 for PostgreSQL).

This automatic networking simplifies inter-service communication setup significantly.

Data Persistence with Volumes

Containers are ephemeral; data inside them is lost if the container is removed. For databases, this is a critical problem!

Docker volumes provide a way to persist data generated by Docker containers. We can use a named volume to store our database's data outside the container, ensuring it survives container restarts or removals.

version: '3.8'
services:
  database:
    image: 'postgres:13'
    environment:
      POSTGRES_DB: mydatabase
      POSTGRES_USER: user
      POSTGRES_PASSWORD: password
    volumes:
      - db_data:/var/lib/postgresql/data
volumes:
  db_data:

Building Custom Images

Often, you'll have your own application code (like a Spring Boot JAR) that needs to be built into a Docker image. Docker Compose can handle this too.

Instead of specifying an image, you can use the build key and point to the directory containing your Dockerfile.

Compose will then build your custom image before starting the service. Here's how it looks:

# docker-compose.yml
version: '3.8'
services:
  my-app:
    build: ./my-app-dir
    ports:
      - '8080:8080'

# my-app-dir/Dockerfile
FROM openjdk:17-jdk-slim
COPY target/my-app.jar app.jar
ENTRYPOINT ["java", "-jar", "app.jar"]

Key Docker Compose Commands

Once your docker-compose.yml is ready, a few commands will be essential for managing your application stack:

  • docker compose up: Builds (if needed) and starts all services. Use -d for detached mode.
  • docker compose down: Stops and removes containers, networks, and optionally volumes.
  • docker compose ps: Lists all running services defined in the Compose file.
  • docker compose logs: Shows log output from services.

Remember to run these commands in the directory where your docker-compose.yml file is located.

Quick Check: Compose Essentials

Consider a docker-compose.yml file that defines two services: web and db.

Which of the following statements about how these services communicate and store data are generally TRUE?

在交互式课程中回答

Recap: Your Multi-Container Powerhouse

Congratulations! You've learned how Docker Compose simplifies the management of multi-container applications.

You can now define your entire application stack in a single docker-compose.yml file, including web services, databases, and custom-built images.

This tool is incredibly useful for local development and testing of microservices, allowing you to spin up your whole environment with just one command. Keep practicing!

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常见问题解答

「使用 Docker Compose 管理容器」课时是免费的吗？

是的 — 「使用 Docker Compose 管理容器」的完整文本可在网页上免费阅读。要进行交互式练习（内置代码编辑器和全天候 AI 导师）并解锁 Spring Boot 4 Microservices & REST APIs 课程的其余内容，请升级到 CoddyKit PRO。 Spring Boot 4 Microservices & REST APIs 课程共包含 3 节课。

「使用 Docker Compose 管理容器」这节课中我会学到什么？

使用 Docker Compose 编排微服务所需的多个 Docker 容器。 你通过在浏览器中直接运行的动手代码来练习 Spring Boot 4 Microservices & REST APIs，全天候 AI 导师会在你学习这节课的过程中回答你的问题。

学习 Spring Boot 4 Microservices & REST APIs 需要有经验吗？

无需任何先前经验。CoddyKit 上的 Spring Boot 4 Microservices & REST APIs 课程适合初学者到高级学习者，你可以从这里开始或从头开始，按照自己的节奏学习。 这是第 2 节课，共 3 节。

「使用 Docker Compose 管理容器」课时需要多长时间？

大多数 CoddyKit 课程大约需要 5–10 分钟。每节课都很精短且互动，所以你能稳步进步，并在网页和应用中从离开的地方继续。

我能在这节 Spring Boot 4 Microservices & REST APIs 课中编写并运行代码吗？

能。每节 Spring Boot 4 Microservices & REST APIs 课都包含内置代码编辑器，你可以在浏览器中直接编写并运行真实代码，并获得即时 AI 反馈 — 无需本地设置。

此课程中的所有课时

  1. 将 Spring Boot 应用容器化
  2. 使用 Docker Compose 管理容器
  3. 容器编排概念
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