This is the right image for your VDE (Vtiger Development Environment)

Add to your Dockerfile FROM javanile/vtiger-dev:7.1.0 instead of FROM javanile/vtiger:7.1.0

If you want use XDebug add the following service on docker-compose.yml to enable host machine routing of xdebug remote machine

services: . . xdebug: image: javanile/xdebug cap_add: [ 'NET_ADMIN', 'NET_RAW' ] restart: on-failure 

NOTICE: In addiction add xdebug in section links of your vtiger service.

This image will be used for Debugging

This image was provided with ad Debug tool for file inside container (generally not visible by developer)

Run the following command with expected output (it keep alive during development)

$ docker-compose exec vtiger debug Preparing 'debug' directory... Add your file settings on 'debug/Debugfile' Watching for debug... (Stop with [Ctrl+C]) 

NOTICE: If you want more control try to edit the file debug/Debugfile and add the following line.

Your are ready to change your files in the IDE (eg. config.inc.php) and keep-alive debug console

Preparing 'debug' directory... Add your file names on '.debug/.debugfile' Watching for debug... (Stop with [Ctrl+C]) > Updated: config.inc.php 

Now the file config.inc.php is ready and connected to your debugging tool, place your var_dump($_GET) everywhere.

Look to your browser if you see something like this

array(3) ( "module" => "Users", "action" => "Login", ) 

It works perfectly.