Precautions for migrating mod_php to PHP-FPM

Due to its unique advantages, PHP-FPM has gradually become the first choice for large-load websites at this stage. Recently, I was asked by my friends to migrate an older website from Apache + mod_php to nginx + PHP-FPM. In addition to the compatibility problems caused by PHP version upgrades, many compatibility problems come from the features of PHP-FPM. Here is a simple list of the problems encountered for your reference.

The first concern is the $ _ server ["http_referer"] environment variable. This problem often occurs on the page to jump to, and is displayed as jump to the whiteboard.

Many codes use $ _ server ["http_referer"] to obtain the URL of the last accessed page. For mod_php, because the method of embedding the HTTP server directly, PHP can easily obtain the http_referer variable. However, for PHP-FPM in CGI Mode, this environment variable cannot be obtained. My personal solution is to get it by refreshing a cookie. It looks clumsy, but the amount of code changes is very small. You may say this is easy to tamper with, but in fact, even the environment variables obtained by mod_php are easy to tamper.

Next is $ _ server ["HTTPS"]. This issue often occurs during redirection. This issue is most likely caused by exceptions in all redirection URLs.

In mod_php, the $ _ server ["HTTPS"] variable only appears after HTTPS is enabled. Otherwise, empty ($ _ server ["HTTPS"]) = true, the value of PHP-FPM always exists, but $ _ server ["HTTPS"] = NULL at http. Although $ _ server ["HTTPS"] = NULL is equivalent to empty ($ _ server ["HTTPS"]) = true, it is not true under the "thirds" condition.

The corresponding $ _ server variable issues include X-forward * and so on.

Then there is the rewrite rule, which is actually a problem of compatibility between APACHE and nginx and has nothing to do with PHP.

I personally think that the jump rules of Apache and nginx are basically common, even if you use NotePad to replace the full text. For example:

RewriteRule ^(.*.(css|js))$ min/index.php?f=$1 [L]

Convert to nginx

rewrite "^(.*.(css|js))$"              /min/index.php?f=$1     last;

Of course, nginx does not support. htaccess and needs to be written to the configuration file.

The execution time is incorrect. Most of the errors are 502 errors. To tell the truth, I don't have a good solution. I have to plan it in advance.

Unlike mod_php, When you execute a script for a long time, once the threshold value is exceeded (10 seconds by default), PHP-FPM automatically closes the execution and returns 502 to the front-end. I personally think this is a protective setting relative to mod_php, which is an advantage and should not be disabled.

Process control functions are rarely used.

Php-FPM uses a non-blocking thread pool. This type of function should not appear and should be used with caution.

TIPS: $ _ env variable

Compared with mod_php, the $ _ env variable is an advantage for enterprise development, especially for enterprises separated from development and O & M, this makes it easy to develop environment-independent code-O & M changes $ _ env variable. developers can read this variable without too much communication between them. Corresponds to the Env [temp] =/tmp or 5.3 <value name = "environment"> <value name = "tmp">/tmp </value> label in the 5.2 FPM configuration file