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
CMDcommand 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.
Cannot connect to localhost:9010 using service:jmx:rmi:///jndi/rmi://localhost:9010/jmxrmi. Jconsole:Connection failed: error during JRMP connection establishment; nested exception is: java.net.SocketException: Connection reset– Kaden