One unix socket for all php-fpm pools

Question

I want to set only one listening unix socket for all php-fpm pools, but fpm requires them to be different.

Production server has 2GB ram and I noticed that it is running out of RAM, adding more websites spawn more fpm processes. I am the only user on this server, so i don't need to limit resources per pool just want to set common config settings for all.

One domain pool as follows:

  [domain.com]
    user = www
    group = www
    listen = /tmp/domain.com-php-fpm.sock
    security.limit_extensions = .php .html

   ;Resources
   pm = dynamic
   pm.max_children = 9
   pm.start_servers = 3
   pm.min_spare_servers = 2
   pm.max_spare_servers = 4
   pm.process_idle_timeout = 60s
   request_terminate_timeout = 30s
   pm.max_requests = 300

   ;Log errors
   catch_workers_output = yes
   php_flag[display_errors]   = on
   php_admin_value[error_log] = /var/log/www/domain.com/php-error.log

   ;Base dirs
   php_admin_value[open_basedir] = /usr/local/www/domain.com
   php_admin_value[upload_tmp_dir] = /usr/local/www/domain.com/tmp 
   php_admin_value[session.save_path] = /usr/local/www/domain.com/tmp

Another pool is the same, except domain name. So then if I set same listening socket for both pools it doesn't work

# php-fpm --test
[12-Sep-2013 22:27:01] ERROR: [pool domain.com] unable to set listen address as it's already used in another pool 'domain2.com'
[12-Sep-2013 22:27:01] ERROR: failed to post process the configuration
[12-Sep-2013 22:27:01] ERROR: FPM initialization failed

And if set different sockets, it works, but each pool spawn minimum 3 process. (Sure, this is not an output from real server, just simulated same behavior).

# ps aux | grep php-fpm
root   1349   0.0  0.9 161376 18320 ??  Ss   10:34PM   0:00.02 php-fpm: master process (/usr/local/etc/php-fpm.conf) (php-fpm)
www    1350   0.0  0.9 161336 18292 ??  S    10:34PM   0:00.00 php-fpm: pool domain2.com (php-fpm)
www    1351   0.0  0.9 161336 18292 ??  S    10:34PM   0:00.00 php-fpm: pool domain2.com (php-fpm)
www    1352   0.0  0.9 161336 18292 ??  S    10:34PM   0:00.00 php-fpm: pool domain2.com (php-fpm)
www    1353   0.0  0.9 161336 18292 ??  S    10:34PM   0:00.00 php-fpm: pool domain.com (php-fpm)
www    1354   0.0  0.9 161336 18292 ??  S    10:34PM   0:00.00 php-fpm: pool domain.com (php-fpm)
www    1355   0.0  0.9 161336 18292 ??  S    10:34PM   0:00.00 php-fpm: pool domain.com (php-fpm)

My intention is to keep running 3 php-fpm processes for all pools.

Answer 1

You can have each nginx server block point at same socket and in the /etc/nginx/fastcgi_params there are the lines:

fastcgi_param   DOCUMENT_URI        $document_uri;
fastcgi_param   DOCUMENT_ROOT       $document_root;

These will cause the document root from your nginx server block to be passed through to php-fpm.

server {
    root /var/www/<%= @title %>/public;
    ...
}

You should then omit the line php_admin_value[open_basedir] = /usr/local/www/domain.com from your php-fpm pool config file.

I believe nginx can do a similar thing to change the log, session and uploads directory, or you can change the error, session and upload handler in php to log to a relative path based on your document root.