Upgrading Legacy to the Latest PHP Version

Your application runs on an old PHP version that is about to go out of support. How to upgrade without breaking the application? You will need the right tools for detecting and fixing those issues, as well as a way to verify that the application is still working correctly. In this presentation, I will share the strategy that I employed when upgrading millions of lines of untested code.

Transcript

1. Upgrading Legacy to the Latest PHP Version IPC MUNICH | OCT 28, 2021 @afilina
2. "I don't know whether my application works on the latest PHP."
3. • Check compatibility. • Fix issues. • Test the fixes.
4. Anna Filina • Coding since 1997 (VB4) • PHP since 2003 • Legacy archaeology • Test automation • Public speaking • Mentorship • YouTube videos
5. Docker image PHPCO PHPCompatibility
6. phpco() { docker run --init -v $PWD:/mnt/src:cached --rm -u "$(id -u):$(id -g)" frbit/phpco:latest $@; return $?; }
7. phpco -p --colors --extensions=php --runtime-set testVersion 7.4 .
8. FILE: /mnt/src/app/controllers/MyController.php ------------------------------------------------------------------ FOUND 1 ERROR AFFECTING 1 LINE ------------------------------------------------------------------ 166 | ERROR | Using 'break' outside of a loop or switch structure | | is invalid and will throw a fatal error since PHP | | 7.0 ------------------------------------------------------------------
9. public function myFunction($result) { if ($result == null) { break; } }
10. public function myFunction($result) { if ($result == null) { return; } }
11. PHPCompatibility tells us what to fix.
12. Fixing
13. $response = '1234567890'; $header = 'Content-length: ' . strlen($response) + 1; echo $header;
14. 3v4l.org
18. $response = '1234567890'; $header = 'Content-length: ' . (strlen($response) + 1); echo $header;
19. Function each() is deprecated since PHP 7.2; Use a foreach loop instead
20. while (list($i, $row) = each($result)) foreach ($result as $i => $row)
21. $i = each($result)['key']; $v = each($result)['value']; $i = each($result)[0]; $v = each($result)[1];
22. $a = each($result); $b = each($result);
23. else if (list(, $optArg) = each($args))
24. final class Php56Compatibility { public static function each(array &$array) { if (current($array) === false) { return false; } $key = key($array); $value = current($array); next($array); return [ 1 => $value, 'value' => $value, 0 => $key, 'key' => $key, ]; } }
25. Portable, unit-tested solution wrapped in a class.
26. We can clean things up at a later time (technical debt).
27. mcrypt PHP
28. mcrypt PECL PHP
29. mcrypt PECL PHP libmcrypt
30. PHP openssl
31. mcrypt.OFB != openssl.OFB
32. How to test mcrypt to openssl upgrade?
33. • Can we decrypt what we just encrypted? • Can we decrypt what we already have in our database?
34. encrypted App with mcrypt original
35. public function testCanDecrypt() { //... $decrypted = $security->decrypt($encrypted); self::assertEquals($original, $decrypted); }
36. mysql_ mysqli_ PDO
37. • Connection object needs to be available. • Connection object now a mysqli type. • Field metadata represented differently. • Different methods for unbuffered queries.
38. mysql to mysqli conversion can't be unit-tested.
39. mysql_connect mysql_query mysql_close mysqli_connect mysqli_query mysqli_close $connection
40. /login redirect to profile credentials session database encryption
41. /login redirect to profile credentials POST /login Redirect URL
42. $response = $this->guzzle->send($request); self::assertEquals(/**/);
43. You can use this approach to test the entire application.
44. PHPCO won't detect everything.
45. <?php class MyClass extends BaseClass { public function validate($field, $value) { //... } } class BaseClass { public function validate(string $field, $value, $message = null) { //... } }
47. • Start testing. • Note the errors that appear. • Tune static analysis for those specific errors.
48. Write more tests.
49. var_dump(0 == "");
51. What about the framework?
52. • New framework might be too different. • Is there a fork that keeps up with PHP?
53. You could make the framework compatible.
54. What about the tests?
55. • Is PHPUnit compatible with PHP? • Can it be updated? • Might need to upgrade PHPUnit.
56. Do not fix your tests and code at the same time.
57. /login redirect to profile credentials POST /login Redirect URL
58. Tests PHP 8.0 PHP 5.4 Application
59. Tests PHP 8.0 PHP 8.0 Application
60. • Use PHPCompatibility • Use Psalm, PHPStan, etc. • Don't be afraid to fix the framework/libs. • Write tests.
61. @afilina Questions?