I have B application which calls A application.
Here are the source code for them:
A application :
@SpringBootApplication
@RestController
@Slf4j
public class AApplication {
public static void main(String[] args) {
SpringApplication.run(AApplication.class, args);
}
@GetMapping("call_a")
public double callA() {
log.info("calling a");
return Math.random();
}
}
with the content of application.properties being :
server.port=6601
B application :
@SpringBootApplication
@RestController
@Slf4j
public class BApplication {
public static void main(String[] args) {
SpringApplication.run(BApplication.class, args);
}
@GetMapping("call_b")
public String callB() {
RestTemplate restTemplate = new RestTemplate();
log.info("calling b");
log.info("calling inner a");
ResponseEntity<String> responseEntity = restTemplate.getForEntity("http://localhost:6601/call_a", String.class);
log.info("called inner a and got {}", responseEntity.getBody());
return responseEntity.getBody();
}
}
with the content of application.properties being :
server.port=6602
Not introducing docker, if I call call_b endpoint from B application it returns successfully.
$ curl http://localhost:6602/call_b
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 18 100 18 0 0 61 0 --:--:-- --:--:-- --:--:-- 610.7818520533385139
But now if I introduce the application inside docker I cannot access them:
Here it is the Dockerfile for both applications:
FROM openjdk:11
ARG JAR_FILE=target/*.jar
COPY ${JAR_FILE} app.jar
ENTRYPOINT ["java","-jar","/app.jar"]
Here it is the docker-compose.yaml to start them both using docker-compose up.
version: '3.7'
services:
cA:
image: gigi/a:latest
ports:
- "6601:6601"
cB:
image: gigi/b:latest
extra_hosts:
- "localhost:host-gateway"
- "127.0.0.1:host-gateway"
- "0.0.0.0:host-gateway"
ports:
- "6602:6602"
It starts them both.
If I enter the B container and just call the call_a endpoint it works:
$ curl http://localhost:6601/call_a
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 18 0 18 0 0 135 0 --:--:-- --:--:-- --:--:-- 1350.7802319051705794
But if I call the call_b endpoint, either inside the B container or outside it will give me:
$ curl http://localhost:6602/call_b
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 107 0 107 0 0 548 0 --:--:-- --:--:-- --:--:-- 551{"timestamp":"2022-07-13T14:38:01.395 00:00","status":500,"error":"Internal Server Error","path":"/call_b"}
And If I look at the logs for the B application I see:
cB_1 | 2022-07-13 14:58:24.787 INFO 1 --- [nio-6602-exec-1] com.example.b.BApplication : calling b
cB_1 | 2022-07-13 14:58:24.787 INFO 1 --- [nio-6602-exec-1] com.example.b.BApplication : calling inner a
cB_1 | 2022-07-13 14:58:24.829 ERROR 1 --- [nio-6602-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 org.springframework.web.client.ResourceAccessException: I/O error on GET request for "http://localhost:6601/call_a": Connection refused (Connection refused); nested exception is java.net.ConnectException: Connection refused (Connection refused)] with root cause
cB_1 |
cB_1 | java.net.ConnectException: Connection refused (Connection refused)
cB_1 | at java.base/java.net.PlainSocketImpl.socketConnect(Native Method) ~[na:na]
cB_1 | at java.base/java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:412) ~[na:na]
cB_1 | at java.base/java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:255) ~[na:na]
cB_1 | at java.base/java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:237) ~[na:na]
cB_1 | at java.base/java.net.Socket.connect(Socket.java:609) ~[na:na]
cB_1 | at java.base/java.net.Socket.connect(Socket.java:558) ~[na:na]
cB_1 | at java.base/sun.net.NetworkClient.doConnect(NetworkClient.java:182) ~[na:na]
cB_1 | at java.base/sun.net.www.http.HttpClient.openServer(HttpClient.java:474) ~[na:na]
cB_1 | at java.base/sun.net.www.http.HttpClient.openServer(HttpClient.java:569) ~[na:na]
cB_1 | at java.base/sun.net.www.http.HttpClient.<init>(HttpClient.java:242) ~[na:na]
cB_1 | at java.base/sun.net.www.http.HttpClient.New(HttpClient.java:341) ~[na:na]
cB_1 | at java.base/sun.net.www.http.HttpClient.New(HttpClient.java:362) ~[na:na]
cB_1 | at java.base/sun.net.www.protocol.http.HttpURLConnection.getNewHttpClient(HttpURLConnection.java:1253) ~[na:na]
cB_1 | at java.base/sun.net.www.protocol.http.HttpURLConnection.plainConnect0(HttpURLConnection.java:1187) ~[na:na]
cB_1 | at java.base/sun.net.www.protocol.http.HttpURLConnection.plainConnect(HttpURLConnection.java:1081) ~[na:na]
cB_1 | at java.base/sun.net.www.protocol.http.HttpURLConnection.connect(HttpURLConnection.java:1015) ~[na:na]
cB_1 | at org.springframework.http.client.SimpleBufferingClientHttpRequest.executeInternal(SimpleBufferingClientHttpRequest.java:76) ~[spring-web-5.3.21.jar!/:5.3.21]
cB_1 | at org.springframework.http.client.AbstractBufferingClientHttpRequest.executeInternal(AbstractBufferingClientHttpRequest.java:48) ~[spring-web-5.3.21.jar!/:5.3.21]
cB_1 | at org.springframework.http.client.AbstractClientHttpRequest.execute(AbstractClientHttpRequest.java:66) ~[spring-web-5.3.21.jar!/:5.3.21]
cB_1 | at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:776) ~[spring-web-5.3.21.jar!/:5.3.21]
cB_1 | at org.springframework.web.client.RestTemplate.execute(RestTemplate.java:711) ~[spring-web-5.3.21.jar!/:5.3.21]
cB_1 | at org.springframework.web.client.RestTemplate.getForEntity(RestTemplate.java:361) ~[spring-web-5.3.21.jar!/:5.3.21]
cB_1 | at com.example.b.BApplication.callB(BApplication.java:27) ~[classes!/:0.0.1-SNAPSHOT]
cB_1 | at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
cB_1 | at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:na]
cB_1 | at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:na]
cB_1 | at java.base/java.lang.reflect.Method.invoke(Method.java:566) ~[na:na]
cB_1 | at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:205) ~[spring-web-5.3.21.jar!/:5.3.21]
cB_1 | at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:150) ~[spring-web-5.3.21.jar!/:5.3.21]
cB_1 | at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:117) ~[spring-webmvc-5.3.21.jar!/:5.3.21]
cB_1 | at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:895) ~[spring-webmvc-5.3.21.jar!/:5.3.21]
cB_1 | at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:808) ~[spring-webmvc-5.3.21.jar!/:5.3.21]
cB_1 | at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) ~[spring-webmvc-5.3.21.jar!/:5.3.21]
cB_1 | at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1067) ~[spring-webmvc-5.3.21.jar!/:5.3.21]
cB_1 | at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:963) ~[spring-webmvc-5.3.21.jar!/:5.3.21]
cB_1 | at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006) ~[spring-webmvc-5.3.21.jar!/:5.3.21]
cB_1 | at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:898) ~[spring-webmvc-5.3.21.jar!/:5.3.21]
cB_1 | at javax.servlet.http.HttpServlet.service(HttpServlet.java:655) ~[tomcat-embed-core-9.0.64.jar!/:na]
cB_1 | at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883) ~[spring-webmvc-5.3.21.jar!/:5.3.21]
cB_1 | at javax.servlet.http.HttpServlet.service(HttpServlet.java:764) ~[tomcat-embed-core-9.0.64.jar!/:na]
cB_1 | at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:227) ~[tomcat-embed-core-9.0.64.jar!/:na]
cB_1 | at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.64.jar!/:na]
cB_1 | at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) ~[tomcat-embed-websocket-9.0.64.jar!/:na]
cB_1 | at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.64.jar!/:na]
cB_1 | at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.64.jar!/:na]
cB_1 | at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100) ~[spring-web-5.3.21.jar!/:5.3.21]
cB_1 | at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117) ~[spring-web-5.3.21.jar!/:5.3.21]
cB_1 | at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.64.jar!/:na]
cB_1 | at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.64.jar!/:na]
cB_1 | at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93) ~[spring-web-5.3.21.jar!/:5.3.21]
cB_1 | at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117) ~[spring-web-5.3.21.jar!/:5.3.21]
cB_1 | at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.64.jar!/:na]
cB_1 | at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.64.jar!/:na]
cB_1 | at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201) ~[spring-web-5.3.21.jar!/:5.3.21]
cB_1 | at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117) ~[spring-web-5.3.21.jar!/:5.3.21]
cB_1 | at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.64.jar!/:na]
cB_1 | at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.64.jar!/:na]
cB_1 | at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:197) ~[tomcat-embed-core-9.0.64.jar!/:na]
cB_1 | at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:97) ~[tomcat-embed-core-9.0.64.jar!/:na]
cB_1 | at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:541) ~[tomcat-embed-core-9.0.64.jar!/:na]
cB_1 | at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:135) ~[tomcat-embed-core-9.0.64.jar!/:na]
cB_1 | at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) ~[tomcat-embed-core-9.0.64.jar!/:na]
cB_1 | at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:78) ~[tomcat-embed-core-9.0.64.jar!/:na]
cB_1 | at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:360) ~[tomcat-embed-core-9.0.64.jar!/:na]
cB_1 | at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:399) ~[tomcat-embed-core-9.0.64.jar!/:na]
cB_1 | at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65) ~[tomcat-embed-core-9.0.64.jar!/:na]
cB_1 | at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:890) ~[tomcat-embed-core-9.0.64.jar!/:na]
cB_1 | at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1787) ~[tomcat-embed-core-9.0.64.jar!/:na]
cB_1 | at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) ~[tomcat-embed-core-9.0.64.jar!/:na]
cB_1 | at org.apache.tomcat.util.threads.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1191) ~[tomcat-embed-core-9.0.64.jar!/:na]
cB_1 | at org.apache.tomcat.util.threads.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:659) ~[tomcat-embed-core-9.0.64.jar!/:na]
cB_1 | at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) ~[tomcat-embed-core-9.0.64.jar!/:na]
cB_1 | at java.base/java.lang.Thread.run(Thread.java:829) ~[na:na]
If you could point me to some documentation to find out, why I couldn't access the other docker container, it would be great?
I do not have the liberty to replace localhost with something else.
Edit 1
I can't modify the source code for the callB application, meaning the localhost:6601/call_a shouldn't be modified.
CodePudding user response：
Because you use localhost inside container b, it means you try to send this rest call inside environment of container b.
I saw you are using docker-compose, so container b is in the same network of container a.
Instead of use localhost, try to use the name of the container A (restTemplate.getForEntity("http://cA:6601/call_a", String.class);)
Let me know if you can reach it.
CodePudding user response：
I was looking for this answer:
The cA application does not expose any port, but it is being set to use the network_mode and the cB application has access to the cA application using localhost.
version: '3.7'
services:
cA:
image: gigi/a:latest
network_mode: "service:cB"
# ports:
# - "6601:6601"
cB:
image: gigi/b:latest
ports:
- "6602:6602"