systemd-notify example daemon

Installing the example

After downloading the example to the /opt/systemd-notify/examples/lookupd directory, cd to the directory and execute:

composer install

Edit the lookupd.service file and adjust the User, and Group entries according to your needs, then execute:

sudo install lookupd.service

Running & testing the daemon

Starting the daemon is now as easy as just asking systemd: sudo systemctl start lookupd and if the service started correctly, no further output is produced.

Getting the service status

We can now query the status of our service by asking systemd:

[Andy@Awesome lookupd]$ sudo systemctl status lookupd
? lookupd.service - Example service to lookup hostnames
   Loaded: loaded (/etc/systemd/system/lookupd.service; disabled; vendor preset: disabled)
   Active: active (running) since Sun 2017-10-29 15:00:01 GMT; 5s ago
 Main PID: 32033 (php)
   Status: "Listening on 127.0.0.1:7777; Served 0 client(s)"
    Tasks: 1 (limit: 4915)
   CGroup: /system.slice/lookupd.service
           ??32033 /usr/bin/php /opt/systemd-notify/examples/lookupd/lookupd-start.php

This output tells us several things; it shows that the service is running properly and sending heartbeat (watchdog) events, and a status message.

A script has also been provided to test the daemon, let's run that a couple of times:

[Andy@Awesome lookupd]$ for counter in {1..10}; do php test-lookup.php; done
localhost.localdomain
localhost.localdomain
localhost.localdomain
localhost.localdomain
localhost.localdomain
localhost.localdomain
localhost.localdomain
localhost.localdomain
localhost.localdomain
localhost.localdomain

Now check the status again

[Andy@Awesome lookupd]$ sudo systemctl status lookupd
? lookupd.service - Example service to lookup hostnames
   Loaded: loaded (/etc/systemd/system/lookupd.service; disabled; vendor preset: disabled)
   Active: active (running) since Sun 2017-10-29 15:09:05 GMT; 9min ago
 Main PID: 32033 (php)
   Status: "Listening on 127.0.0.1:7777; Served 10 client(s)"
    Tasks: 1 (limit: 4915)
   CGroup: /system.slice/lookupd.service
           ??32033 /usr/bin/php /opt/systemd-notify/examples/lookupd/lookupd-start.php

Of course this is a contrived example but it clearly demonstrates how this package can be used in your own services.