Cannot start redis server on Centos 7 with systemctl - redis

Question

I have some trouble in starting Redis on CentOS7 with systemctl. What should I do to troubleshoot?
I can use the normal command to start the Redis. Like:
# /etc/init.d/redis start
or
/usr/local/bin/redis-server /etc/redis/config.conf
And here is my redis.service file which I put into /lib/systemd/system:
[Unit]
Description=Redis persistent key-value database
After=network.target
[Service]
Type=forking
PIDFILE=/var/run/redis_6379.pid
ExecStart=/etc/init.d/redis start
ExecStop=/etc/init.d/redis stop
PrivateTmp=true
[Install]
WantedBy=multi-user.target
But when I use command systemctl start redis to start redis server. I got nothing.
I try to use systemctl status redis to read the systemctl log, it shows me these messages:
● redis.service - Redis persistent key-value database
Loaded: loaded (/usr/lib/systemd/system/redis.service; disabled; vendor preset: disabled)
Active: active (exited) since Fri 2018-08-31 15:45:37 CST; 2 days ago
Aug 31 15:45:37 redisserver001 systemd[1]: Starting LSB: start and stop redis_6379...
Aug 31 15:45:37 redisserver001 systemd[1]: Started LSB: start and stop redis_6379.
Aug 31 15:45:37 redisserver001 redis[24755]: /var/run/redis_6379.pid exists, process is already running or crashed
Sep 03 10:31:21 redisserver001 systemd[1]: [/usr/lib/systemd/system/redis.service:6] Unknown lvalue 'PIDFILE' in section 'Service'
Sep 03 10:33:13 redisserver001 systemd[1]: [/usr/lib/systemd/system/redis.service:6] Unknown lvalue 'PIDFILE' in section 'Service'
Sep 03 10:45:32 redisserver001 systemd[1]: [/usr/lib/systemd/system/redis.service:7] Unknown lvalue 'PIDFILE' in section 'Service'
Sep 03 11:08:28 redisserver001 systemd[1]: [/usr/lib/systemd/system/redis.service:7] Unknown lvalue 'PIDFILE' in section 'Service'
The following items is the key configration that I think could impact the redis running. But I donn't know where I've make mistakes. Please help. Thanks a lot.
pidfile /var/run/redis_6379.pid
daemonize yes
supervised systemd

Answer 1

If an application specifies the "pidfile" property in the service file, then its the responsibility of the application to write the pid of the main process into that file, before the service initialization is complete. You need to make sure that your application is doing that. Systemd will read this value, and will prevent another forked process from being created if the user executes the "systemctl start ", and the pid file already exists. From the output you posted, it seems like systemd believes that the redis process is already running (because of the presence of the pid file, and doesnt create a new one). You can set the pid in the "ExecStartPost" clause of the service file. Something like:
ExecStartPost=/bin/sh -c 'umask 022; pgrep YOURSERVICE > /var/run/YOURSERVICE.pid'

Answer 2

The option must be PIDFile (case sensetive). From the manpage man systemd.service
PIDFile=
Takes a path referring to the PID file of the service. Usage of this option is recommended for
services where Type= is set to forking. The path specified typically points to a file below /run/. If
a relative path is specified it is hence prefixed with /run/. The service manager will read the PID
of the main process of the service from this file after start-up of the service. The service manager
will not write to the file configured here, although it will remove the file after the service has
shut down if it still exists. The PID file does not need to be owned by a privileged user, but if it
is owned by an unprivileged user additional safety restrictions are enforced: the file may not be a
symlink to a file owned by a different user (neither directly nor indirectly), and the PID file must
refer to a process already belonging to the service.