In PHP =< 5.4, there was APC. And in APC, there was the
apc.stat option to check the timestamps on files to determine if they’ve changed, and a new version should be cached. However, in PHP 5.5+, it introduces OPCode Caching as an alternative to APC, and that works a bit differently.
Now, with PHP 5.5 and the new OPcache things are a bit different. OPcache is not inode-based so we can’t use the same trick [symlink-changes for deploys].
In short: if the “path” to your document root or PHP doesn’t actually change, PHP’s OPcache will not reload your PHP code.
Flush the PHP opcache
So if your PHP code is in the following directory structure, and the
current symlink is changed to point to a new release directory, the OPCache won’t read the new file since the
path of the file remains the same.
$ ls current -> releases/20141217084854 releases/20141217084854 releases/20141217085023
current symlink changes from
releases/20141217085023, you need to manually clear the OPCache to have it load the new PHP files.
There is no mechanisme (yet?) in OPCache that allows you to
stat the source files and check for changes. There are options like
opcache.revalidate_freq that allow you to periodically check for changes, but that’s always time-based.
So to clear the OPCache after each deploy, you now have two options:
- Reload or restart the PHP-FPM daemon (you’ll need sudo-rights for this)
- Use a tool like cachetool to flush the OPCache via the CLI
This is something to keep in mind.
Nginx fix: use $real_path instead
If you’re using Nginx as the webserver in front of your PHP there is also a configuration change you can make to let nginx resolve the symlinks. The result is that PHP does not see the symlink, but it’s docroot is shown as a directory that points to releases/20141217084854.
In your Nginx configuration, you probably have a configuration directive that looks like this.
fastcgi_index index.php; fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name; fastcgi_param DOCUMENT_ROOT $document_root;
The keypoint here is
$document_root in the fastcgi_param. That points to the docroot of Nginx, usually
If you change the Nginx configuration to use
$realpath_root instead of
$document_root, Nginx will resolve the symlink and will let that variable refer to the full path to your deploy, being
So the entire snippet looks like this:
fastcgi_index index.php; fastcgi_param SCRIPT_FILENAME $realpath_root$fastcgi_script_name; fastcgi_param DOCUMENT_ROOT $realpath_root;
This may introduce other bugs in your code (such as a change in the $_SERVER variables in PHP or
../../-style symlinks that won’t refer to the same path again), but it will also solve your PHP OPcache troubles.