Xdebug

Xdebug's (remote) debugger allows you to examine data structure, The Xdebug extension provides debugging
and profiling capabilities for PHP scripts.
Xdebug supports PHP 5.4, 5.5, 5.6, 7.0, 7.1, 7.2, and 7.3.
You can debug your PHP coding using built functions like print_r() or var_dump() or using log file however this is not enough and it will slow you down during developing.
by using Magento2+xdebug it will speed you up during developing and it will make your life easier

Installing Xdebug

Preconditions

you have Magento2+Vagrant environment
※ If you don't have Magento2+Vagrant environment you can follow this tutorial magento2: 개발 환경 구축 Vagrant

PHP version is 7.1~

you already install PHPSTORM

install Xdebug (inside Vagrant)

inside-vagrant

sudo pecl install xdebug

On my server, I got the following output.
inside-vagrant-output

Build process completed successfully
Installing '/usr/lib/php/20151012/xdebug.so'
install ok: channel://pecl.php.net/xdebug-2.6.1
configuration option "php_ini" is not set to php.ini location
You should add "zend_extension=/usr/lib/php/20151012/xdebug.so" to php.ini

Next, we need to enable the xdebug extension by modifying the php.ini configuration file/etc/php/7.1/fpm/php.ini or /etc/php/7.1/fpm/conf.d/20-xdebug.iniinside-vagrant

sudo vim /etc/php/7.1/fpm/php.ini

/etc/php/7.1/fpm/php.ini

zend_extension=/usr/lib/php/20151012/xdebug.so
xdebug.remote_host=192.168.33.10
xdebug.remote_enable=1
xdebug.remote_port=9900
xdebug.idekey="PHPSTORM"
xdebug.remote_log="/tmp/xdebug.log"

xdebug.remote_host You can set it to a specific domain or a IP address. im my case I set 192.168.33.10 because it is my vagrant private network IP
xdebug.remote_port You can set it to a specific port by default it will be 9000 In case I set to 9000 since my 9000 port is listen to something else.
xdebug.idekey since I use PHPSTORM ID I setted to PHPSTORMxdebug.remote_log it is used as filename to a file to which all remote debugger communications are logged.
after setting you to need to restart your web server.
in case you Apache
inside-vagrant

sudo /etc/init.d/apache2 restart

in case you Nginx
inside-vagrant

sudo /etc/init.d/nginx restart

To verify if xdebug successfully enable. You can add phpinfo() into [magento-folder]/pub/index.php
in my case, it was /var/www/html/pub/index.phpyou should get output like this.

Configuring XDebug client

In my case, I will Configure PHPStorm IDEA
open your project in phpstorm
you will set the port as you set it in php.ini of xdebug.remote_portphpstorm

PHPSTORM -> Preference -> Languages & Frameworks -> PHP -> Debug

PHPstorm configuration

Deployment configure

phpstorm

phpstorm -> Preference -> Build, Execution, Deployment -> Deployment

add a new remote server by click on [+] icon

host You can set it to a specific domain or an IP address
username remote server username since we use vagrant username will be vagrantpassword remote server password since we use vagrant password will be vagrantroot path vagrant Magento folder absolute location /var/www/html/

Servers configure

phpstorm

PHPSTORM -> Preference -> Languages & Frameworks -> PHP -> Servers

add a new server by click on [+] icon

host You can set it to a specific domain or an IP address
Use path mapping check the checkbox
under project files set the vagrant Magento folder absolute location /var/www/html/

Run/debug configure

phpstorm

PHPSTORM ->Toolbar ->Edit Configurations

add a new debug by click on [+] icon

select PHP Remote Debug

Server selected Server we already create it on the last step.
IDE key you will set the IDE key as you set it in php.ini of xdebug.idekey

Browser Configuration

Install xdebug chrome extension Xdebug helper

after install extension set IDE key

on chrome -> toolbar-> xdebug chrome extension icon right click

2.select Phpstorm set IDE key you will set the IDE key as you set it in php.ini of xdebug.idekey
3.click on save button

enable xdebug chrome extension

on chrome -> toolbar-> xdebug chrome extension icon left click

2. click on debug

debug Time!

phpstorm

PHPSTORM -> toolbar 

On the PhpStorm toolbar, toggle the Start Listening for PHP Debug Connections button to start listening for incoming PHP debug connections, or choose Run | Start Listening for PHP Debug Connections from the main menu.

Set a breakpoint in your code. Breakpoints can be set in the PHP context inside we set on Magento pub/index.php
3.on browser refresh website it automatically redirects to PHPstorm
https://gyazo.com/c11de6afa9e6b666a5ff3ef7b983a37d