PHP-FPM does not create socket on service restart

Question

Issue & Question

Ubuntu Server 18.04 LTS.

Using systemctl restart on PHP-FPM doesn't create the required socket in /var/run/php/, but a reboot does.

How can I tweak my setup to allow a service restart without a reboot?

Overview

I'm compiling multiple PHP-FPM instances from source on a single server (no containers) for use with web apps of various ages. I have successfully set up PHP 7.1, PHP 7.2 and PHP 7.3 alongside one another. They all start correctly at boot, they all have a socket in /var/run/php/, they all respond as expected from a browser.

Contents of `/var/run/php` after boot

/var/run/php$ ls -l
total 0
srw-rw---- 1 www-data www-data 0 Apr  2 12:57 php7.1-fpm.sock
srw-rw---- 1 www-data www-data 0 Apr  2 12:57 php7.2-fpm.sock
srw-rw---- 1 www-data www-data 0 Apr  2 12:57 php7.3-fpm.sock

Each service appears to be running without issue. Here's the systemctl status output for each:

PHP 7.1 after boot

~$ sudo systemctl status php7.1-fpm
● php7.1-fpm.service - The PHP FastCGI Process Manager
   Loaded: loaded (/etc/systemd/system/php7.1-fpm.service; enabled; vendor preset: enabled)
   Active: active (running) since Tue 2019-04-02 12:57:51 UTC; 21min ago
 Main PID: 875 (php-fpm)
    Tasks: 3 (limit: 1152)
   CGroup: /system.slice/php7.1-fpm.service
           ├─875 php-fpm: master process (/etc/php/7.1/etc/php-fpm.conf)
           ├─970 php-fpm: pool www
           └─971 php-fpm: pool www

Apr 02 12:57:51 darwin systemd[1]: Started The PHP FastCGI Process Manager.

PHP 7.2 after boot

~$ sudo systemctl status php7.2-fpm
● php7.2-fpm.service - The PHP FastCGI Process Manager (7.2)
   Loaded: loaded (/etc/systemd/system/php7.2-fpm.service; enabled; vendor preset: enabled)
   Active: active (running) since Tue 2019-04-02 12:57:51 UTC; 22min ago
 Main PID: 837 (php-fpm)
    Tasks: 3 (limit: 1152)
   CGroup: /system.slice/php7.2-fpm.service
           ├─837 php-fpm: master process (/etc/php/7.2/etc/php-fpm.conf)
           ├─963 php-fpm: pool www
           └─964 php-fpm: pool www

Apr 02 12:57:51 darwin systemd[1]: Started The PHP FastCGI Process Manager (7.2).

PHP 7.3 after boot

~$ sudo systemctl status php7.3-fpm
● php7.3-fpm.service - The PHP FastCGI Process Manager (7.3)
   Loaded: loaded (/etc/systemd/system/php7.3-fpm.service; enabled; vendor preset: enabled)
   Active: active (running) since Tue 2019-04-02 12:57:51 UTC; 23min ago
 Main PID: 836 (php-fpm)
    Tasks: 3 (limit: 1152)
   CGroup: /system.slice/php7.3-fpm.service
           ├─836 php-fpm: master process (/etc/php/7.3/etc/php-fpm.conf)
           ├─965 php-fpm: pool www
           └─966 php-fpm: pool www

Apr 02 12:57:51 darwin systemd[1]: Started The PHP FastCGI Process Manager (7.3).

If I make a change to the respective php.ini file, this warrants a restart of the service in order for changes to be processed. In my case, when I restart the service using systemctl restart (e.g sudo systemctl restart php7.1-fpm), the service appears to restart gracefully but all the PHP sockets are deleted -- regardless of the version I restart.

There's no console output after the systemctl restart, and when I check systemctl status on the restarted service (e.g PHP 7.1 in previous paragraph), the service is running:

PHP 7.1 after `systemctl restart`

~$ sudo systemctl status php7.1-fpm
● php7.1-fpm.service - The PHP FastCGI Process Manager
   Loaded: loaded (/etc/systemd/system/php7.1-fpm.service; enabled; vendor preset: enabled)
   Active: active (running) since Tue 2019-04-02 13:28:06 UTC; 28s ago
 Main PID: 1704 (php-fpm)
    Tasks: 3 (limit: 1152)
   CGroup: /system.slice/php7.1-fpm.service
           ├─1704 php-fpm: master process (/etc/php/7.1/etc/php-fpm.conf)
           ├─1718 php-fpm: pool www
           └─1722 php-fpm: pool www

Apr 02 13:28:06 darwin systemd[1]: Stopped The PHP FastCGI Process Manager.
Apr 02 13:28:06 darwin systemd[1]: Started The PHP FastCGI Process Manager.

Note the timestamp difference on Active. If I query the other services in the same fashion (note: they have not been restarted by me), the timestamps are from the initial start at boot:

PHP 7.2 after `systemctl restart` on PHP 7.1

~$ sudo systemctl status php7.2-fpm
● php7.2-fpm.service - The PHP FastCGI Process Manager (7.2)
   Loaded: loaded (/etc/systemd/system/php7.2-fpm.service; enabled; vendor preset: enabled)
   Active: active (running) since Tue 2019-04-02 12:57:51 UTC; 33min ago
 Main PID: 837 (php-fpm)
    Tasks: 3 (limit: 1152)
   CGroup: /system.slice/php7.2-fpm.service
           ├─837 php-fpm: master process (/etc/php/7.2/etc/php-fpm.conf)
           ├─963 php-fpm: pool www
           └─964 php-fpm: pool www

Apr 02 12:57:51 darwin systemd[1]: Started The PHP FastCGI Process Manager (7.2).

PHP 7.3 after `systemctl restart` on PHP 7.1

~$ sudo systemctl status php7.3-fpm
● php7.3-fpm.service - The PHP FastCGI Process Manager (7.3)
   Loaded: loaded (/etc/systemd/system/php7.3-fpm.service; enabled; vendor preset: enabled)
   Active: active (running) since Tue 2019-04-02 12:57:51 UTC; 34min ago
 Main PID: 836 (php-fpm)
    Tasks: 3 (limit: 1152)
   CGroup: /system.slice/php7.3-fpm.service
           ├─836 php-fpm: master process (/etc/php/7.3/etc/php-fpm.conf)
           ├─965 php-fpm: pool www
           └─966 php-fpm: pool www

Apr 02 12:57:51 darwin systemd[1]: Started The PHP FastCGI Process Manager (7.3).

…and yet all the sockets are missing:

Contents of `/var/run/php` after `systemctl restart` on PHP 7.1

$ ls -l
total 0

My gut feeling is that I've mangled something in the .service file without realising. While I've been troubleshooting, I've noticed I'm using different directories for the PID and socket. The PID is not created at boot time as /run/php-fpm/ does not exist. I have a vague memory of being advised to not keep sockets and PIDs in the same directory, but I can't recall the exact details.

PHP 7.1 `.service` file

[Unit]
Description=The PHP FastCGI Process Manager
After=network.target

[Service]
Type=simple
RuntimeDirectory=php
RuntimePermissions=755
PIDFile=/run/php-fpm/php7.1-fpm.pid
ExecStart=/etc/php/7.1/sbin/php-fpm --nodaemonize --fpm-config /etc/php/7.1/etc/php-fpm.conf
ExecReload=/bin/kill -USR2 $MAINPID

[Install]
WantedBy=multi-user.target

Thank you in advance for any pointers or further reading.

score 6 · Accepted Answer · answered Apr 02 '19 at 17:32

On further investigation, it turns out I was missing a RuntimeDirectoryPreserve directive in my unit file. When the service was stopped, the RuntimeDirectory was deleted…along with the sockets.

Excerpt from systemd.exec

RuntimeDirectoryPreserve= Takes a boolean argument or restart. If set to no (the default), the directories specified in RuntimeDirectory= are always removed when the service stops. If set to restart the directories are preserved when the service is both automatically and manually restarted. Here, the automatic restart means the operation specified in Restart=, and manual restart means the one triggered by systemctl restart foo.service. If set to yes, then the directories are not removed when the service is stopped. Note that since the runtime directory /run is a mount point of "tmpfs", then for system services the directories specified in RuntimeDirectory= are removed when the system is rebooted.

Revised (working) unit file:

[Unit]
Description=The PHP FastCGI Process Manager (7.1)
After=network.target nginx.service

[Service]
Type=simple
RuntimeDirectory=php
RuntimeDirectoryMode=755
RuntimeDirectoryPreserve=yes
PIDFile=/run/php7.1-fpm.pid
ExecStart=/etc/php/7.1/sbin/php-fpm --nodaemonize --fpm-config /etc/php/7.1/etc/php-fpm.conf
ExecReload=/bin/kill -USR2 $MAINPID

[Install]
WantedBy=multi-user.target

PHP-FPM does not create socket on service restart

Issue & Question

Overview

Contents of /var/run/php after boot

PHP 7.1 after boot

PHP 7.2 after boot

PHP 7.3 after boot

PHP 7.1 after systemctl restart

PHP 7.2 after systemctl restart on PHP 7.1

PHP 7.3 after systemctl restart on PHP 7.1

Contents of /var/run/php after systemctl restart on PHP 7.1

PHP 7.1 .service file

1 Answers1