Getting started with systemd
This document provides simple introduction of
systemd and steps for your application to accomplish it.
systemd is an init system that provides many powerful features for starting, stopping, reload configuration and managing processes. Refer to systemd man page.
systemd consists of two main concepts:
- A unit is a configuration file that describes the properties of the process that you’d like to run.
- A target is a grouping mechanism that allows systemd to start up groups of processes at the same time. This happens at every boot as processes are started at different run levels.
Note: Ensure the rights are set correctly and provide ownership to the user you want to use. Here, I'll use the
aah user account.
Table of Contents
- Steps to Configure and Enable
- How to Start, Stop, Restart, Reload and Status
Since v0.10 aah CLI includes
generate command to help developer in application development. To generate application
.service file, use below command.
# run anywhere aah generate script --name systemd --importpath github.com/user/appname # OR if you're in app directory or path aah generate script --name systemd # OR short form aah g s -n systemd
Steps to Configure and Enable
- Place your service file at
/etc/systemd/system/. For e.g.:
- We are gonna reload it, execute
sudo systemctl daemon-reload.
sudo systemctl enable aahwebsite.service.
- Congrats, you have successfully created and enabled your application service.
How to Start, Stop, Restart, Reload and Status
Now let’s see how to utilize the service file. Don’t forget to replace your service file/name with below example commands :).
Start your application
sudo systemctl start aahwebsite.service # OR sudo systemctl start aahwebsite # OR sudo service aahwebsite start
Stop your application
sudo systemctl stop aahwebsite.service # OR sudo systemctl stop aahwebsite # OR sudo service aahwebsite stop
Restart your application
sudo systemctl restart aahwebsite.service # OR sudo systemctl restart aahwebsite # OR sudo service aahwebsite restart
Reload your application
Since v0.10 Reload functionality available.
sudo systemctl reload aahwebsite.service # OR sudo systemctl reload aahwebsite # OR sudo service aahwebsite reload
Status of your application
sudo systemctl status aahwebsite.service # OR sudo systemctl status aahwebsite # OR sudo service aahwebsite status
You will get similar output:
● aahwebsite.service - aahframework.org Loaded: loaded (/etc/systemd/system/aahwebsite.service; enabled; vendor preset: enabled) Active: active (running) since Fri 2017-09-22 17:05:20 PDT; 6s ago Process: 16623 ExecStart=/home/aah/website/aah.sh start (code=exited, status=0/SUCCESS) Main PID: 16629 (aahwebsite) Tasks: 6 Memory: 8.4M CPU: 748ms CGroup: /system.slice/aahwebsite.service └─16629 /home/aah/website/bin/aahwebsite -profile=prod Sep 22 17:05:20 cn01-sfo.aahframework.org systemd: Starting aahframework.org... Sep 22 17:05:20 cn01-sfo.aahframework.org aah.sh: aahwebsite started. Sep 22 17:05:20 cn01-sfo.aahframework.org systemd: Started aahframework.org.
systemd service file
For your reference. This is
aahframework.org website service file. aah application deployed/extracted at location
[Unit] Description=aahframework.org After=network.target [Service] EnvironmentFile=/home/aah/website/env_values User=aah Group=aah Type=forking ExecStart=/home/aah/website/aah.sh start ExecStop=/home/aah/website/aah.sh stop ExecReload=/bin/kill -HUP $MAINPID Restart=on-failure [Install] WantedBy=multi-user.target