The document discusses using Xdebug to debug PHP code. It begins with an overview of Xdebug, explaining that it is a PHP extension that allows for step-by-step debugging and profiling of PHP applications. It then covers how to set up Xdebug, including installing the extension, configuring an IDE like PhpStorm to work with it, setting breakpoints in code, and activating the debugger. Finally, it discusses how to use Xdebug, such as setting and working with breakpoints, stepping through code, and using watches and the console window. The overall document serves as an introduction to debugging PHP applications with Xdebug.

1. D E B U G G I N G P H P W I T H
X D E B U G
M A R K N I E B E R G A L L
https://joind.in/talk/50bee

3. D E B U G G I N G P H P W I T H
X D E B U G

4. A B O U T M A R K N I E B E R G A L L
• PHP since 2005
• Masters degree in MIS
• Senior Software Engineer
• Drug screening project
• UPHPU President
• CSSLP, SSCP Certified and SME
• Drones, fishing, skiing, father, husband

5. A B O U T M A R K N I E B E R G A L L
• Manchester
• Nelson
• Workington

6. A B O U T M A R K N I E B E R G A L L

7. A B O U T M A R K N I E B E R G A L L

8. D E B U G G I N G P H P W I T H X D E B U G
Overview
• What is Xdebug
• Why use Xdebug
• Setting up Xdebug
• Using Xdebug

9. W H AT I S X D E B U G

10. W H AT I S X D E B U G

11. W H AT I S X D E B U G
Xdebug
• Step-into debugger
• Profiler
• DeBugGer Protocol (DBGp) for communication

12. W H AT I S X D E B U G
Xdebug
• Available since 2002
• Developed initially by Derick Rethans
• PHP extension
• Written in C
• Open source

13. W H Y U S E X D E B U G

14. W H Y U S E X D E B U G
Debugging without Xdebug

15. W H Y U S E X D E B U G
Debugging without Xdebug
• echo $something;
• var_dump($other);
• print_r($data);
• error_log(__FILE__ . ‘ line ‘ . __LINE__);

16. W H Y U S E X D E B U G
Debugging without Xdebug
1. Add outputs
2. Load page
3. Look for output
4. Change some code
5. Add more outputs
6. Repeat
7. Cleanup outputs without missing any
8. Load page

17. W H Y U S E X D E B U G
Debugging with Xdebug

18. W H Y U S E X D E B U G
Debugging with Xdebug
1. Turn on debugging
2. Add breakpoint(s)
3. Load page
4. Step into the code

19. W H Y U S E X D E B U G
Debugging with Xdebug
• Live values
• Follow actual code path
• Full stacktrace

20. W H Y U S E X D E B U G
Debugging with Xdebug
• Supported by most IDEs
• Faster development time
• Better understanding of what code is actually doing
• Does not require code changes to interrogate values

21. S E T T I N G U P X D E B U G

22. S E T T I N G U P X D E B U G
Fire up you development environment

23. S E T T I N G U P X D E B U G
Documentation from JetBrain for PhpStorm
https://confluence.jetbrains.com/display/PhpStorm/Zero-
configuration+Web+Application+Debugging+with+Xdebug+and+PhpStorm
1. Install Xdebug
2. Prepare PhpStorm
3. Set a breakpoint in the source code
4. Activate debugger on server
5. Start a debug session in browser
6. Reload the current page
7. Set initial path mappings

24. S E T T I N G U P X D E B U G
1. Install Xdebug

25. S E T T I N G U P X D E B U G
1. Install Xdebug
• https://xdebug.org/docs/install

26. S E T T I N G U P X D E B U G
1. Install Xdebug
• Download (if applicable)
• Install or compile
• Configure PHP
• Restart webserver

27. S E T T I N G U P X D E B U G
1. Install Xdebug
• git clone https://github.com/xdebug/xdebug.git
• cd xdebug
• ./rebuild.sh

28. S E T T I N G U P X D E B U G
1. Install Xdebug
• Windows:
- Xdebug website has a wizard, dll downloads
• Mac:
- sudo pecl install xdebug
- brew install php72-xdebug
• Linux:
- wget http://xdebug.org/files/xdebug-2.6.0.tgz
- sudo pecl install xdebug

29. S E T T I N G U P X D E B U G
1. Install Xdebug
• Windows: download dll
- Xdebug website has a wizard, downloads
- Paste php -i or phpinfo() (ex: C:phpphp -i > C:
phpphpinfo.txt or <?php phpinfo();)
- dll download link provided
- Add a line to your php.ini file
- Restart webserver

30. S E T T I N G U P X D E B U G
1. Install Xdebug
• apt-get install php-xdebug
• wget http://xdebug.org/files/xdebug-2.6.0.tgz
tar -xzvf xdebug-2.6.0.tgz
cd xdebug-2.6.0
phpize
./configure --enable-xdebug
make
make install

31. S E T T I N G U P X D E B U G
1. Install Xdebug
• yum install php-devel
yum install php-pear
pecl install xdebug
• dnf install php-devel
dnf install php-pear
pecl install xdebug

32. S E T T I N G U P X D E B U G
1. Install Xdebug
• Update php.ini by adding lines:
zend_extension = php_xdebug-2.6.0-7.2-vc15-nts-x86_64.dll
[xdebug]
xdebug.remote_enable = 1
xdebug.remote_autostart = 1
xdebug.remote_port = 9000
xdebug.remote_host = localhost
xdebug.idekey = PHPSTORM

33. S E T T I N G U P X D E B U G
1. Install Xdebug
• Update php.ini by adding lines:
zend_extension = /usr/lib64/php/modules/xdebug.so
[xdebug]
xdebug.remote_enable = 1
xdebug.remote_autostart = 1
xdebug.remote_port = 9000
xdebug.remote_host = localhost
xdebug.idekey = PHPSTORM

34. S E T T I N G U P X D E B U G
1. Install Xdebug
• Restart webserver
- Windows:
Services
Apache Monitor
- Linux:
sudo apachectl restart
sudo service nginx restart

35. S E T T I N G U P X D E B U G
1. Install Xdebug
• Verify via phpinfo
- <?php phpinfo();
- php -i | grep xdebug

36. S E T T I N G U P X D E B U G
1. Install Xdebug
• Verify via phpinfo

37. S E T T I N G U P X D E B U G
1. Install Xdebug
• Verify via phpinfo

38. S E T T I N G U P X D E B U G
2. Prepare PhpStorm

39. S E T T I N G U P X D E B U G
2. Prepare PhpStorm
• Start Listening for PHP Debug Connections

40. S E T T I N G U P X D E B U G
2. Prepare PhpStorm

41. S E T T I N G U P X D E B U G
2. Prepare PhpStorm

42. S E T T I N G U P X D E B U G
2. Prepare PhpStorm
• Setup debug settings

44. S E T T I N G U P X D E B U G
2. Prepare PhpStorm
• Setup project path mapping

45. S E T T I N G U P X D E B U G
2. Prepare PhpStorm

46. S E T T I N G U P X D E B U G
3. Set a breakpoint in the source code

47. S E T T I N G U P X D E B U G
3. Set a breakpoint in the source code
• Line you know will be hit
• Or break on first line

49. S E T T I N G U P X D E B U G
4. Activate debugger on server

50. S E T T I N G U P X D E B U G
4. Activate debugger on server
• Browser plugin, add-on
- The easiest Xdebug (Firefox)
- Xdebug Helper (Chrome)
- Xdebug Toggler (Safari)
- Xdebug launcher (Opera)

51. S E T T I N G U P X D E B U G
4. Activate debugger on server

52. S E T T I N G U P X D E B U G
4. Activate debugger on server

53. S E T T I N G U P X D E B U G
4. Activate debugger on server
• URL
- GET: &XDEBUG_SESSION_START=PHPSTORM
- POST: XDEBUG_SESSION_START=PHPSTORM
• Headers
- Name: Cookie
- Value: XDEBUG_SESSION=PHPSTORM
• Bookmarklet

54. S E T T I N G U P X D E B U G
4. Activate debugger on server

55. S E T T I N G U P X D E B U G
4. Activate debugger on server

56. S E T T I N G U P X D E B U G
4. Activate debugger on server

57. S E T T I N G U P X D E B U G
4. Activate debugger on server

58. S E T T I N G U P X D E B U G
4. Activate debugger on server

59. S E T T I N G U P X D E B U G
4. Activate debugger on server

60. S E T T I N G U P X D E B U G
4. Activate debugger on server

61. S E T T I N G U P X D E B U G
5. Start a debug session in browser

62. S E T T I N G U P X D E B U G
5. Start a debug session in browser
• Click the debug button in toolbar
• Add GET, POST, or COOKIE

63. S E T T I N G U P X D E B U G
6. Reload the current page

64. S E T T I N G U P X D E B U G
6. Reload the current page

65. S E T T I N G U P X D E B U G
7. Set initial path mappings

66. S E T T I N G U P X D E B U G
7. Set initial path mappings

67. U S I N G X D E B U G

68. U S I N G X D E B U G

69. U S I N G X D E B U G
• Breakpoints
• Stepping through code
• Watches
• Console

70. U S I N G X D E B U G

71. U S I N G X D E B U G
Breakpoints
• Pause code execution at specific line
• Allowed multiple breakpoints
• Conditional breakpoints

72. U S I N G X D E B U G
Breakpoints
• Place strategically
• Not too early
• Not too late
• Not too many
• Remember time limit, increase if needed
• Use conditional breakpoints in loops

73. U S I N G X D E B U G
Breakpoints

74. U S I N G X D E B U G
Breakpoints

75. U S I N G X D E B U G
Stepping through code

76. U S I N G X D E B U G
Stepping through code
• Resume Program (Play)
• Stop
• View Breakpoints
• Disable All Breakpoints

77. U S I N G X D E B U G
Stepping through code
• Step Over
• Step Into
• Force Step Into
• Step Out
• Run to Cursor

78. U S I N G X D E B U G
Stepping through code
• Evaluate Expression
• Show value addresses
• Hide empty superglobal variables (on by default)
• Add method to skip list

79. U S I N G X D E B U G
Watches

80. U S I N G X D E B U G
Watches
• Live updates
• Values
• Expressions

81. U S I N G X D E B U G
Console

82. U S I N G X D E B U G
Console
• Output from debugging expressions
• Enter expressions to be evaluated

83. S U M M A RY

84. S U M M A RY
• More efficient way to debug
• Visibility into code
• Ability to change code on the fly
• Watch values change line by line
• Better understanding of code path

85. D I S C U S S I O N
• Setup issues
• Remote debugging
• Profiling
• Xdebug vs alternative methods

86. Q U E S T I O N S ?
https://joind.in/talk/50bee

87. S O U R C E S
• JetBrains documentation https://confluence.jetbrains.com/display/PhpStorm/Zero-
configuration+Web+Application+Debugging+with+Xdebug+and+PhpStorm
• Xdebug documentation https://xdebug.org/docs/install
• David Stockton, php[architect], January 2015, https://www.phparch.com/wp-
content/uploads/2015/01/levelup-xdebug-phparchitect-jan2015.pdf
• https://sievertschreiber.files.wordpress.com/2010/04/crane-truck-double-fail.jpg