我们有一个 API，可以使用 Java API 将对象放入 AWS S3。它在以下位置运行良好：
- 从我们的本地开发工作站
- 来自 EC2 机器中的生产 docker 容器内部。
但是，同样的 API 在我们本地测试服务器中运行的 docker 容器中不起作用。调试问题时，我们发现了一个java.net.UnknownHostException: s3.ap-south-1.amazonaws.com
我们进入 docker 容器 shell，并对pingS3 端点执行了操作，但无法连接：
/ # ping s3.ap-south-1.amazonaws.com
ping: bad address 's3.ap-south-1.amazonaws.com'
/ # ping s3.ap-south-1.amazonaws.com
ping: bad address 's3.ap-south-1.amazonaws.com'
我们的 Docker 版本是20.10.16, build aa7e414
我们的 Docker 容器正在运行openjdk:8-alpine
主机正在运行 Ubuntu20.04.4 LTS (Focal Fossa)
以下是完整的堆栈跟踪：
java.net.UnknownHostException: s3.ap-south-1.amazonaws.com
at java.net.InetAddress.getAllByName0(InetAddress.java:1281) ~[na:1.8.0_212]
at java.net.InetAddress.getAllByName(InetAddress.java:1193) ~[na:1.8.0_212]
at java.net.InetAddress.getAllByName(InetAddress.java:1127) ~[na:1.8.0_212]
at com.amazonaws.SystemDefaultDnsResolver.resolve(SystemDefaultDnsResolver.java:27) ~[aws-java-sdk-core-1.11.163.jar!/:na]
at com.amazonaws.http.DelegatingDnsResolver.resolve(DelegatingDnsResolver.java:38) ~[aws-java-sdk-core-1.11.163.jar!/:na]
at org.apache.http.impl.conn.DefaultHttpClientConnectionOperator.connect(DefaultHttpClientConnectionOperator.java:112) ~[httpclient-4.5.13.jar!/:4.5.13]
at org.apache.http.impl.conn.PoolingHttpClientConnectionManager.connect(PoolingHttpClientConnectionManager.java:376) ~[httpclient-4.5.13.jar!/:4.5.13]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_212]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_212]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_212]
at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_212]
at com.amazonaws.http.conn.ClientConnectionManagerFactory$Handler.invoke(ClientConnectionManagerFactory.java:76) ~[aws-java-sdk-core-1.11.163.jar!/:na]
at com.amazonaws.http.conn.$Proxy62.connect(Unknown Source) ~[na:na]
at org.apache.http.impl.execchain.MainClientExec.establishRoute(MainClientExec.java:393) ~[httpclient-4.5.13.jar!/:4.5.13]
at org.apache.http.impl.execchain.MainClientExec.execute(MainClientExec.java:236) ~[httpclient-4.5.13.jar!/:4.5.13]
at org.apache.http.impl.execchain.ProtocolExec.execute(ProtocolExec.java:186) ~[httpclient-4.5.13.jar!/:4.5.13]
at org.apache.http.impl.client.InternalHttpClient.doExecute(InternalHttpClient.java:185) ~[httpclient-4.5.13.jar!/:4.5.13]
at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:83) ~[httpclient-4.5.13.jar!/:4.5.13]
at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:56) ~[httpclient-4.5.13.jar!/:4.5.13]
at com.amazonaws.http.apache.client.impl.SdkHttpClient.execute(SdkHttpClient.java:72) ~[aws-java-sdk-core-1.11.163.jar!/:na]
at com.amazonaws.http.AmazonHttpClient$RequestExecutor.executeOneRequest(AmazonHttpClient.java:1189) ~[aws-java-sdk-core-1.11.163.jar!/:na]
at com.amazonaws.http.AmazonHttpClient$RequestExecutor.executeHelper(AmazonHttpClient.java:1029) ~[aws-java-sdk-core-1.11.163.jar!/:na]
at com.amazonaws.http.AmazonHttpClient$RequestExecutor.doExecute(AmazonHttpClient.java:741) ~[aws-java-sdk-core-1.11.163.jar!/:na]
at com.amazonaws.http.AmazonHttpClient$RequestExecutor.executeWithTimer(AmazonHttpClient.java:715) ~[aws-java-sdk-core-1.11.163.jar!/:na]
at com.amazonaws.http.AmazonHttpClient$RequestExecutor.execute(AmazonHttpClient.java:697) ~[aws-java-sdk-core-1.11.163.jar!/:na]
at com.amazonaws.http.AmazonHttpClient$RequestExecutor.access$500(AmazonHttpClient.java:665) ~[aws-java-sdk-core-1.11.163.jar!/:na]
at com.amazonaws.http.AmazonHttpClient$RequestExecutionBuilderImpl.execute(AmazonHttpClient.java:647) ~[aws-java-sdk-core-1.11.163.jar!/:na]
at com.amazonaws.http.AmazonHttpClient.execute(AmazonHttpClient.java:511) ~[aws-java-sdk-core-1.11.163.jar!/:na]
at com.amazonaws.services.s3.AmazonS3Client.invoke(AmazonS3Client.java:4227) ~[aws-java-sdk-s3-1.11.163.jar!/:na]
at com.amazonaws.services.s3.AmazonS3Client.invoke(AmazonS3Client.java:4174) ~[aws-java-sdk-s3-1.11.163.jar!/:na]
at com.amazonaws.services.s3.AmazonS3Client.invoke(AmazonS3Client.java:4168) ~[aws-java-sdk-s3-1.11.163.jar!/:na]
at com.amazonaws.services.s3.AmazonS3Client.listBuckets(AmazonS3Client.java:918) ~[aws-java-sdk-s3-1.11.163.jar!/:na]
at com.amazonaws.services.s3.AmazonS3Client.listBuckets(AmazonS3Client.java:924) ~[aws-java-sdk-s3-1.11.163.jar!/:na]
at com.yethi.tenjin.aws.S3Handler.getAllBuckets(S3Handler.java:31) ~[classes!/:0.0.1-SNAPSHOT]
at com.yethi.tenjin.aws.AwsS3DemoApplication.getBuckets(AwsS3DemoApplication.java:33) ~[classes!/:0.0.1-SNAPSHOT]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_212]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_212]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_212]
at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_212]
at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:205) ~[spring-web-5.3.21.jar!/:5.3.21]
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:150) ~[spring-web-5.3.21.jar!/:5.3.21]
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:117) ~[spring-webmvc-5.3.21.jar!/:5.3.21]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:895) ~[spring-webmvc-5.3.21.jar!/:5.3.21]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:808) ~[spring-webmvc-5.3.21.jar!/:5.3.21]
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) ~[spring-webmvc-5.3.21.jar!/:5.3.21]
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1067) ~[spring-webmvc-5.3.21.jar!/:5.3.21]
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:963) ~[spring-webmvc-5.3.21.jar!/:5.3.21]
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006) ~[spring-webmvc-5.3.21.jar!/:5.3.21]
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:898) ~[spring-webmvc-5.3.21.jar!/:5.3.21]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:655) ~[tomcat-embed-core-9.0.64.jar!/:na]
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883) ~[spring-webmvc-5.3.21.jar!/:5.3.21]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:764) ~[tomcat-embed-core-9.0.64.jar!/:na]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:227) ~[tomcat-embed-core-9.0.64.jar!/:na]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.64.jar!/:na]
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) ~[tomcat-embed-websocket-9.0.64.jar!/:na]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.64.jar!/:na]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.64.jar!/:na]
at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100) ~[spring-web-5.3.21.jar!/:5.3.21]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117) ~[spring-web-5.3.21.jar!/:5.3.21]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.64.jar!/:na]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.64.jar!/:na]
at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93) ~[spring-web-5.3.21.jar!/:5.3.21]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117) ~[spring-web-5.3.21.jar!/:5.3.21]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.64.jar!/:na]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.64.jar!/:na]
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201) ~[spring-web-5.3.21.jar!/:5.3.21]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117) ~[spring-web-5.3.21.jar!/:5.3.21]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.64.jar!/:na]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.64.jar!/:na]
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:197) ~[tomcat-embed-core-9.0.64.jar!/:na]
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:97) [tomcat-embed-core-9.0.64.jar!/:na]
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:541) [tomcat-embed-core-9.0.64.jar!/:na]
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:135) [tomcat-embed-core-9.0.64.jar!/:na]
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) [tomcat-embed-core-9.0.64.jar!/:na]
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:78) [tomcat-embed-core-9.0.64.jar!/:na]
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:360) [tomcat-embed-core-9.0.64.jar!/:na]
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:399) [tomcat-embed-core-9.0.64.jar!/:na]
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65) [tomcat-embed-core-9.0.64.jar!/:na]
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:890) [tomcat-embed-core-9.0.64.jar!/:na]
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1787) [tomcat-embed-core-9.0.64.jar!/:na]
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-embed-core-9.0.64.jar!/:na]
at org.apache.tomcat.util.threads.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1191) [tomcat-embed-core-9.0.64.jar!/:na]
at org.apache.tomcat.util.threads.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:659) [tomcat-embed-core-9.0.64.jar!/:na]
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-9.0.64.jar!/:na]
at java.lang.Thread.run(Thread.java:748) [na:1.8.0_212]
除了 S3 端点之外，docker 容器也无法访问其他 URL，例如dl-cdn.alpinelinux.org等。
不确定问题出在哪里，因为几周前它还运行正常。
请帮助我们找到问题所在。