Debugging Tomcat Running in Vagrant using Port Forwarding

Question

I'm trying to attach my Eclipse debugger running on my Windows host to a Tomcat 8 server running in my Vagrant box running CentOS 7.

The issue is something to do with the networking setup of Vagrant I believe.

Here is the full error from the Eclipse logs:

java.net.SocketException: Connection reset
    at java.net.SocketInputStream.read(SocketInputStream.java:179)
    at java.io.DataInputStream.readFully(DataInputStream.java:189)
    at java.io.DataInputStream.readFully(DataInputStream.java:163)
    at org.eclipse.jdi.internal.connect.SocketTransportService.readHandshake(SocketTransportService.java:216)
    at org.eclipse.jdi.internal.connect.SocketTransportService.access$7(SocketTransportService.java:212)
    at org.eclipse.jdi.internal.connect.SocketTransportService$3.run(SocketTransportService.java:183)
    at java.lang.Thread.run(Thread.java:761)

The output from vagrant up seems correct (port 8000 is the debugging port):

==> default: Preparing network interfaces based on configuration...
    default: Adapter 1: nat
==> default: Forwarding ports...
    default: 8000 => 8000 (adapter 1)
    default: 8443 => 8443 (adapter 1)
    default: 22 => 2222 (adapter 1)

I can access my application (using https://localhost:8443/app) via a browser from my host without issue; connecting the debugger is the issue. The debugger is configured for a Remote Java Application with connection properties:

Host: localhost
Port: 8000

Starting Tomcat of course displays the correct:

Listening for transport dt_socket at address: 8000

Based on the following questions, the answer maybe have something to do with configuring Tomcat to run on 0.0.0.0 instead of the default:

Cannot reach Jekyll server on Vagrant from outside
Vagrant port forwarding not working. Cups not accesible from host
Empty reply from server - can't connect to vagrant vm w/port forwarding
Connection Reset when port forwarding with Vagrant

So I tried configuring the Connectors in Tomcat's server.xml with the line address="0.0.0.0" but the result was the same.

Any other ideas about getting this to work? Also, assuming the answer is something to do with changing the address to 0.0.0.0, why would I need to do that to get the debugger to work if accessing the app via browser is already fine on localhost:8443?

P.S. It is not a firewall issue.

Dave L. · Accepted Answer · 2015-06-21 02:37:54Z

2

I was on the right track above changing the address to 0.0.0.0, but I was changing that on the Connector in server.xml, which has nothing to do with the debugger. The resolution is to change the JPDA_ADDRESS resulting in my bin/setenv.sh getting:

JPDA_ADDRESS="0.0.0.0:8000"

This is due to a change in Tomcat 8:

When starting Tomcat with the jpda option to enable remote debugging, Tomcat 8 listens on localhost:8000 by default. Earlier versions listened on *:8000. If required, this default can be overridden by setting the JPDA_ADDRESS environment variable in, for example, setenv.[bat|sh].

answered Jun 21, 2015 at 2:37

Dave L.

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