两个 docker 容器之间的 HTTP 连接被拒绝，而从外部两个容器都可连接

Question

尝试在 2 个 docker-container 之间发出 REST 请求。

更明确地说，我有 2 个 SpringBoot REST 服务映像（A 和 B），A 通过 HTTP 调用 B。

问题

当我在本地（例如在 IDE 中）运行它们时，它们可以正常通信。

但是当我在 Docker 中运行它们时，A 无法连接到 B。但是当我使用 Postman 时，我可以连接到 A 和 B。

• A ( jedi_service) 运行于localhost:8080
• B ( human_cloning_facilities) 运行于localhost:8082

码头工人组成

version: "3.9"
services:
  human_cloning_facilities:
    image: erwanlt94/human_cloning_app:6.0.0
    container_name: human_cloning_app
    restart: unless-stopped
    ports:
      - "8080:8080"

  jedi_service:
    image: erwanlt94/jedi_api:1.0.0
    container_name: jedi_service
    restart: unless-stopped
    ports:
      - "8082:8082"

volumes:
  human_cloning_facilities:
    driver: local
  jedi_service:
    driver: local

日志追踪

当我调用 A 上将连接到 B 的端点时：

2022-06-21 14:44:55.725 ERROR [Human cloning,b8d7c7a112fd94d0,b8d7c7a112fd94d0] 1 --- [nio-8080-exec-1] o.a.c.c.C.[.[.[/].[dispatcherServlet]    : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is feign.RetryableException: Connection refused (Connection refused) executing GET http://127.0.0.1:8082/jedis] with root cause
2022-06-21T14:44:55.727148588Z 
2022-06-21T14:44:55.727162378Z java.net.ConnectException: Connection refused (Connection refused)
2022-06-21T14:44:55.727168574Z  at java.base/java.net.PlainSocketImpl.socketConnect(Native Method) ~[na:na]
2022-06-21T14:44:55.727174195Z  at java.base/java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:412) ~[na:na]
2022-06-21T14:44:55.727179444Z  at java.base/java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:255) ~[na:na]
2022-06-21T14:44:55.727184823Z  at java.base/java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:237) ~[na:na]
2022-06-21T14:44:55.727281097Z  at java.base/java.net.Socket.connect(Socket.java:609) ~[na:na]
2022-06-21T14:44:55.727295172Z  at java.base/sun.net.NetworkClient.doConnect(NetworkClient.java:177) ~[na:na]
2022-06-21T14:44:55.727324103Z  at java.base/sun.net.www.http.HttpClient.openServer(HttpClient.java:474) ~[na:na]
2022-06-21T14:44:55.727330887Z  at java.base/sun.net.www.http.HttpClient.openServer(HttpClient.java:569) ~[na:na]
2022-06-21T14:44:55.727336098Z  at java.base/sun.net.www.http.HttpClient.<init>(HttpClient.java:242) ~[na:na]
2022-06-21T14:44:55.727353809Z  at java.base/sun.net.www.http.HttpClient.New(HttpClient.java:341) ~[na:na]
2022-06-21T14:44:55.727358566Z  at java.base/sun.net.www.http.HttpClient.New(HttpClient.java:362) ~[na:na]
2022-06-21T14:44:55.727363344Z  at java.base/sun.net.www.protocol.http.HttpURLConnection.getNewHttpClient(HttpURLConnection.java:1253) ~[na:na]
2022-06-21T14:44:55.727367999Z  at java.base/sun.net.www.protocol.http.HttpURLConnection.plainConnect0(HttpURLConnection.java:1187) ~[na:na]
2022-06-21T14:44:55.727373095Z  at java.base/sun.net.www.protocol.http.HttpURLConnection.plainConnect(HttpURLConnection.java:1081) ~[na:na]
2022-06-21T14:44:55.727378075Z  at java.base/sun.net.www.protocol.http.HttpURLConnection.connect(HttpURLConnection.java:1015) ~[na:na]
2022-06-21T14:44:55.727383009Z  at java.base/sun.net.www.protocol.http.HttpURLConnection.getInputStream0(HttpURLConnection.java:1592) ~[na:na]
2022-06-21T14:44:55.727391083Z  at java.base/sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1520) ~[na:na]
2022-06-21T14:44:55.727396501Z  at java.base/java.net.HttpURLConnection.getResponseCode(HttpURLConnection.java:527) ~[na:na]
2022-06-21T14:44:55.727401416Z  at feign.Client$Default.convertResponse(Client.java:108) ~[feign-core-10.12.jar!/:na]
2022-06-21T14:44:55.727406394Z  at feign.Client$Default.execute(Client.java:104) ~[feign-core-10.12.jar!/:na]
2022-06-21T14:44:55.727411293Z  at org.springframework.cloud.sleuth.instrument.web.client.feign.TracingFeignClient.execute(TracingFeignClient.java:79) ~[spring-cloud-sleuth-instrumentation-3.1.2.jar!/:3.1.2]
2022-06-21T14:44:55.727416481Z  at org.springframework.cloud.sleuth.instrument.web.client.feign.LazyClient.execute(LazyClient.java:54) ~[spring-cloud-sleuth-instrumentation-3.1.2.jar!/:3.1.2]
2022-06-21T14:44:55.727421646Z  at feign.SynchronousMethodHandler.executeAndDecode(SynchronousMethodHandler.java:119) ~[feign-core-10.12.jar!/:na]
2022-06-21T14:44:55.727426635Z  at feign.SynchronousMethodHandler.invoke(SynchronousMethodHandler.java:89) ~[feign-core-10.12.jar!/:na]
2022-06-21T14:44:55.727431758Z  at feign.ReflectiveFeign$FeignInvocationHandler.invoke(ReflectiveFeign.java:100) ~[feign-core-10.12.jar!/:na]
2022-06-21T14:44:55.727436913Z  at com.sun.proxy.$Proxy189.findAllUsingGET(Unknown Source) ~[na:na]
2022-06-21T14:44:55.727441948Z  at com.erwan.human.controller.HumanCloningController.getAllJedi(HumanCloningController.java:128) ~[classes!/:6.0.0-SNAPSHOT]

问题是什么？

Answer 1

听起来您localhost在尝试连接时正在使用主机名。

在 Docker 上下文中，localhost是容器本身。您可以使用另一个容器的服务名称作为主机名来连接到另一个容器。

因此，当从 human_cloning_facilities 连接到 jedi_service 时，您应该使用http://jedi_service:8082/. 当从 jedi_service 连接到 human_cloning_facilities 时，您应该使用http://human_cloning_facilities:8080/.

当 Docker 创建的桥接网络上的容器之间进行连接时，应使用容器端口。这对您的情况没有影响，因为您将端口映射到主机上的相同端口号。但如果您只需要从网络上的其他容器访问容器，则不需要将端口映射到主机端口。仅当您需要从主机访问容器时才需要这样做。