We’re currently on our way to Kissimmee, FL to join Parallels Summmit, an annual conference from the people who make Plesk. We’re also taking exams in Plesk 10.4.4 so we’re studying it in-depth – I’ve been using the software for over two years now but never had formal training in it. Well here goes!
In preparation for the exam tomorrow I’ve come across something the instructor mentioned: namely the benefits of running PHP as a FastCGI application instead of an Apache module. Sadly I’ve also come across some drawbacks when using this option in regards to WordPress. I thought I’d mention those here, alongside how to avoid those.
UPDATE: Thanks to Boldock this problem can be fixed 😉
Apache Module vs. FastCGI
First of all let’s have a look at why you’d want to run PHP as anything other than an Apache module. More times than I can count I’ve had to tweak ownership or file permissions in WordPress installations to make WordPress read / write / amend files – it needs this to use many of the cool features, such image uploads or one-click upgrades.
If PHP is run as an Apache Module, then when WordPress creates a file it does this as the “apache” user. Similarly, when it needs overwrite files it needs those files to be writable by the Apache group, or the files need to be owned by “apache” (or they need to be 777 so that everyone can overwrite them – which is not good).
If PHP would instead be run as FastCGI, then the actual file owner of the account could let PHP write to it’s own files – they woulnd’t need to be “apache” owned nor writable. That’s great news. Imagine you had 100 websites and all files would be owned by “apache” – it would be a nightmare to track down if a script has gone awry which site it originated from. Therefore, FastCGI is a dream come true. If it would work properly that is.
The Drawbacks for WordPress
Turns out that there are also a couple of drawbacks in regards to WordPress when it comes to using this new Plesk feature:
I tried to install a theme via the ZIP uploader (Over Easy by Woo Themes, it’s 909k in size so not very big), and all I got was a reproducible 500 Internal Server Error. This did not happen when I switched PHP back to being run as an Apache Module.
Also, mobile posting via WordPress for iOS does not work for image sizes large and above. Small and medium sizes still work, but the app gives a “Blog returned invalid data” error – not so when run as an Apache Module.
This could be a bug in Plesk, this could be a memory problem somewhere – I’ll certainly bring it up at the summit. Maybe all uploads of a certain size have a problem, even though it’s not related to the PHP max memory sizes (if tested it with up to 6GB!).
The Solution
The reason this seems to be happening is that FastCGI is running low on memory. By default the Apache configuration does not include a statement to allocate enough memory, but we can do this by adding the following line to httpd.conf (thanks to Baldock for this tip):
FcgidMaxRequestLen 33554432
Restart Apache with “service httpd restart” and all your troubles go away.
Conclusion
FastCGI is a great idea in principle, and if your applications play ball then I’d vote for this option any time. However, if things don’t work out you need to find another way.
Adding the above to your apache config is one option, but only possible if you’re running a dedicated server or VPS. If that’s not the case, you can also switch PHP back to be run as standard CGI Application. It still works fine and provides site isolation over an Apache module.
There are a few other options you have: suPHP, mod_ruid2 and mpm-itk are things to look into, but that’s a bit more hard core to implement. See below for this suggestion from the Parallels Forum.
If everything else fails, I’m afraid you’re stuck with an Apache module and file permission hell.
Either way, stay sane…
Further Reading
Here are some useful links discussing this issue. I’ll add my own future findings on the comments below – feel free contribute.
- We’re discussing this topic in the WordPress Forum – check out an excellent guide by Luke America
- Paul’s blog Return True shows another alternative: we can use CGI instead of FastCGI
- FastCGI Homepage on the Apache Website
- Parallels Forum Thread showing two other options: mod_ruid2 and mpm-itk
I have a problem that I can’t find where to add this line
and conf folder is protected and it keeps saying permission denied
Plesk v.11 with godaddy
Thanks in advance.
forgot to mention that my /etc directory has only a php.ini file can’t modify it.
Could be that you’re in a VPS instead of a dedicated box. I think even though they give you full root access to a VPS certain directories are protected in such a setup.
I think stuff like the conf and etc directory are governed by a higher node to protect the overall system (a VPS is usually one of about 100 instances on one machine). Have a word with Godaddy and see if they can help.
You are awesome!
I was tearing my hair out try to figure out what was going on.
Hey guys. I know this post is a couple months old but I’m going nuts over here and I don’t know many people using Apache with FastCGI for their PHP processing.
I recently updated to PHP 5.4 and I cannot run the WP upgrade at all. Some of my sites are running WP 3.4.2 and when I try to update to 3.5, I receive this funky error in my Apache error_log:
Creating default object from empty value in /var/www/mysite.com/wp-admin/includes/update.php on line 90, referer: http://mysite.com/wp-admin/update-core.php
I’ve read about some patches to the WP core, but my code looks consistent with the patch. I run in to various PHP strict errors, usually due to plugins that need to be updated. Even after deactivating all my plugins and trying to run the update, I still receive that error.
The weird thing is, WP totally says that the update is successful, yet it takes me right back to the ‘Welcome to WordPress 3.4.2’ screen instead of 3.5.