Windows宿主机请求Docker容器中Spring API无响应问题求助

Alright, let's figure out why your containerized Spring API isn't responding when you hit it from your host machine. The main issue here is a port mismatch in your Docker Compose setup, and it's an easy fix!

1. The Port Mapping Mistake #

Look at your docker-compose.yml for the api service:

ports:
  - "8080:80"

This line tells Docker to map your host's port 8080 to the container's port 80. But here's the problem: your Spring Boot application is defaulting to listening on port 8080 inside the container (since you haven't changed the server port via application.properties or startup arguments).

So when you send a request to http://localhost:8080/api/task/ from your host, it's trying to connect to port 80 in the container—where nothing is running. That's why you get the "Server returned nothing" error.

Fix It #

Update the ports section to map host port 8080 to container port 8080:

ports:
  - "8080:8080"

2. Verify the Fix (and Debug Further if Needed) #

After updating the config, stop and restart your containers with:

docker-compose down && docker-compose up --build

Then:

• Test the endpoint again at http://localhost:8080/api/task/—it should work now.
• If it still doesn't respond, check if your Spring app actually started properly in the container. Run this command to view the logs:

  docker logs <your-api-container-name>
  

  Look for a line like Started SpringApiApplication in X seconds (JVM running for Y)—that confirms the app is up. If you see database connection errors, you might need to adjust your SPRING_DATASOURCE_URL or wait a few seconds for MySQL to fully initialize (since depends_on only waits for the container to start, not the database service).
• You can also check which ports the app is listening on inside the container. Exec into the container:

  docker exec -it <your-api-container-name> sh
  

  Then install net-tools (if missing) and check listening ports:

  apt update && apt install net-tools
  netstat -tulpn
  

  You should see java listening on port 8080.

3. Bonus: Optional Port Configuration #

If you want your app to run on port 80 inside the container (to match your original mapping), you can modify your Spring Boot setup:

• Add server.port=80 to your application.properties file, or
• Update the entrypoint in your Dockerfile to pass the port as an argument:

  ENTRYPOINT ["java", "-jar", "-Dserver.port=80", "spring-api-0.0.1-SNAPSHOT.jar"]
  

  Either way, keep the ports: - "8080:80" mapping in your Compose file.

内容的提问来源于stack exchange，提问作者Tiago Martinho