Remote debugging Java 9 in a docker container from IntelliJ IDEA

Question

I have a Dockerfile with this content:

FROM openjdk:9

WORKDIR /project

ADD . /project

EXPOSE 5005

My docker-compose.yml looks like this:

version: "3.2"
services:
  some-project:
    build: .
    ports:
      - target: 5005
        published: 5005
        protocol: tcp
        mode: host
  command: "java '-agentlib:jdwp=transport=dt_socket,server=y,suspend=y,address=5005' SomeClass"

When I do docker-composer up I see a message "Listening for transport dt_socket at address: 5005". But when I try to connect with jdb or Idea I get "java.io.IOException: handshake failed - connection prematurally closed".

Everything works fine if I change openjdk:9 to openjdk:8. However, I need Java 9 for my project.

Answer 1

From Java 9, the JDWP socket connector accept only local connections by default. See: http://www.oracle.com/technetwork/java/javase/9-notes-3745703.html#JDK-8041435

So, to enable debug connections from outside, specify *:<port> as address:

-agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=*:5005