Configuring php-fpm

When configuration php-fpm you are able to configure it using ports or sockets.
The best thing to do is configure with socks as this avoids the networking stack associated with ports.
This means that php-fpm will be using files (sockets) to run which could be considered slower because of potential slow HDDs however the files are mostly stored in RAM so it makes accessing them significantly quicker.

CentOS 7, Ubuntu 12.04 LTS, Ubuntu 14.04 LTS uses FHS 3.0, this means that it uses /run for accessing RAM

Sockets fastcgi_pass unix:/run/php-fpm/example.com.sock
Ports fastcgi_pass 127.0.0.1:9000;


You are still able to refer to the FHS 2.4 as before however you are also able to access /run which is the new structure for 3.0
For example the output of df -h on CentOS 7 looks like: 

# df -h
Filesystem      Size  Used Avail Use% Mounted on
/dev/sda2       1.8T  195G  1.6T  12% /
devtmpfs        1.9G     0  1.9G   0% /dev
tmpfs           1.9G  4.0K  1.9G   1% /dev/shm
tmpfs           1.9G   41M  1.8G   3% /run
tmpfs           1.9G     0  1.9G   0% /sys/fs/cgroup
/dev/sda1       190M   95M   82M  54% /boot


Configuring php-fpm Pool

To specify different server pools for each website you can create a website pool in the /etc/php-fpm.d/ directory.
E.g /etc/php-fpm.d/lukeslinux.co.uk
You would then want something similar to the following: 


[lukeslinux.co.uk]

listen = /run/php-fpm/lukeslinux.co.uk.sock
listen.allowed_clients = 127.0.0.1

user = nginx
group = nginx

pm = dynamic
pm.max_children = 50
pm.start_servers = 5
pm.min_spare_servers = 5
pm.max_spare_servers = 35

slowlog = /var/log/php-fpm/lukeslinux.co.uk-slow.log

php_admin_value[error_log] = /var/log/php-fpm/lukeslinux.co.uk-error.log
php_admin_flag[log_errors] = on

php_value[session.save_handler] = files
php_value[session.save_path] = /var/lib/php/session



Troubleshooting

If you are looking to view the processes, you will need to use different commands depending on how its been configured:

Config Command
socket netstat -plnx grep 'php-fpm'
port netstat -plnt grep 'php-fpm


Example output of netstat -plnx: 

unix 2 [ ACC ] STREAM LISTENING 146689 21372/php-fpm: mast /run/php-fpm/lukeslinux.co.uk.sock


Website Issues

Make sure that php-fpm hasnt hit max processes; 

grep "pm.max_spare_servers" /etc/php-fpm.d/www.conf


ps -eo cmd,pid,pcpu --sort:-pcpu | grep -v grep | grep -c php-fpm