php7.1-fpm and xdebug

gistfile1.txt

ubuntu 16.04

sudo apt-get install php-xdebug

/etc/php/7.1/fpm/php.ini
[xdebug]
xdebug.remote_enable=on
xdebug.remote_handler=dbgp
xdebug.remote_host=localhost
xdebug.remote_port=9000
xdebug.remote_log=/var/log/xdebug.log

sudo systemctl restart php7.1-fpm

open an url on your server and check phpinfo(), make sure you can see 
"with Xdebug v2.5.5, Copyright (c) 2002-2017, by Derick Rethans"

# skip this if you feel confident to your environment, or you can check this guide 
# to compile xdebug/debugclient to ensure your php-fpm is configured correctly
# https://walty8.com/remotely-debug-php-using-command-line-vim-vdebug-xdebug/

.vimrc
Plugin 'joonty/vdebug'

let g:vdebug_options = {'break_on_open': 0}
let g:vdebug_options = {'server': 'localhost'}
let g:vdebug_options = {'port': '9000'}
# remote debug need path mapping
#let g:vdebug_options = {'path_maps': {'/remote/path/to/webroot': '/local/path/to/webroot'}}

vi /var/www/html/index.php

# Set a break point by Pressing 
Press F10
# At this point your editor window will change, your vim probably not supporting python

# Start debugging
Press F5

# you should see this meesage at the bottom of vim windows
Waiting for a connection (Ctrl-C to cancel, this message will self-destruct in  20  seconds...)

# Open the page with ?XDEBUG_SESSION_START=1
Open browse with url http://yourwebsite?XDEBUG_SESSION_START=1

# If nothing happen when you press F5 or F10, then your vim probably not support python 2, 
# check this thread to confirm that https://github.com/joonty/vdebug/issues/101
# launch vim
vi

# try this command, 
:python debugger.run() 

# this message means your vim does not support python
E319: Sorry, the command is not available in this version

# If this is the case, then do the following steps to change your vim to vim.nox-py2
sudo apt-get install vim-nox vim-nox-py2
sudo update-alternatives --set vi /usr/bin/vim.nox-py2

# open the file to debug again, you should see the Waiting for a connection message now

References
https://xdebug.org/docs/all
https://github.com/joonty/vdebug
https://github.com/joonty/vdebug/issues/303
http://www.sromero.org/wiki/linux/servicios/php/vim_debug_basics
https://mutelight.org/minimal-guide-to-debugging-php-with-xdebug-and-vim
https://gist.github.com/rahilwazir/74c6be0a452f505da8e1
https://github.com/laradock/laradock/issues/102
https://devforgalaxy.github.io/zh/2016/09/14/debug-containerised-php-app-using-xdebug-with-vim-and-vdebug-zh.html