How do I attach VisualVM to a simple Java process running in a Docker container

Question

Actually I wanted a solution working for JEE containers, specifically for Glassfish, but after I tried many combinations of settings and did not succeed, I reduced the setup to the simplest possible case.

Here is my Hello World daemon started in a Docker container. I want to attach jconsole or VisulaVM to it. Everything is on the same machine.

public class Main {   public static void main(String[] args) {     while (true) {       try {         Thread.sleep(3000);         System.out.println("Hello, World");       } catch (InterruptedException e) {         break;       }     }   } } 

Dockerfile

FROM java:8 COPY . /usr/src/myapp WORKDIR /usr/src/myapp RUN javac Main.java CMD ["java", "Main"] 

Building: docker build -t hello-world-daemon .

Running: docker run -it --rm --name hwd hello-world-daemon

Questions:

• what JVM parameters should be added to CMD command line?
• what ports should be exposed and published?
• what network mode should Docker container be using?

I do not show my failed attempts here so that correct answers will not be biased. This should be a pretty common problem, yet I could not find a working solution.

Update. Worked solution

This Dockerfile works

FROM java:8 COPY . /usr/src/myapp WORKDIR /usr/src/myapp RUN javac Main.java CMD ["java", \ "-Dcom.sun.management.jmxremote", \ "-Dcom.sun.management.jmxremote.port=9010", \ "-Dcom.sun.management.jmxremote.local.only=false", \ "-Dcom.sun.management.jmxremote.authenticate=false", \ "-Dcom.sun.management.jmxremote.ssl=false", "Main"] EXPOSE 9010 

in combination with the docker run command

docker run -it --rm --name hwd -p 9010:9010 hello-world-daemon 

VisualVM connects via right click Local->Add JMX Connection, and then entering localhost:9010, or through adding a remote host.

JConsole connects via selecting a Remote process with localhost:9010.

When defining the connection as remote, any interface listed by ifconfig can be used. For instance, docker0 interface with address 172.17.0.1 works. The container's address 172.17.0.2 works too.

Answer 1

At first you should run you application with these JVM params:

-Dcom.sun.management.jmxremote -Dcom.sun.management.jmxremote.port=9010 -Dcom.sun.management.jmxremote.local.only=false -Dcom.sun.management.jmxremote.authenticate=false -Dcom.sun.management.jmxremote.ssl=false 

Then you should expose port for docker:

EXPOSE 9010 

Also specify port binding with docker run command:

docker run -p 9010:9010 -it --rm --name hwd hello-world-daemon 

After that you can connect with Jconsole to local 9010 port and manage application run in Docker.