upstart init.d systemd — A Simple Instruction

28 May 2018 in linux / devops on ubuntu

• systemd is now supported by most linux system, and is the recommended way contrast to old upstart and init
• the systemd config file is under /lib/systemd/system
• env vars only able to be set in ExecStart or ExecStartPre, best way is to set in the script
• WorkingDirectory can not use double quote, seems to be a bug?
• if you app run like java -jar, should use Type=simple instead of Type=forking, otherwise it will case a timeout

after move the config under the folder /lib/systemd/system

#auto-start sudo systemctl enable servicename.service #reload sudo systemctl daemon-reload

Run/Stop Service

#start sudo systemctl start servicename.service #stop sudo systemctl stop servicename.service

View log

#view status, little log systemctl status servicename.service #view the last 50 lines systemctl status service-name -n50 #view all the log systemctl --no-pager -l status servicename.service #view all the log journalctl -u service-name.service #view the last 50 lines journalctl -n 50 --no-pager -u service-name.service #tail the log journalctl -f -u service-name.service

Example

Myexample [Unit] Description=Example [Service] Type=simple #for java, should not be forking #note the bash should specify its full path ExecStart=/bin/bash /home/ubuntu/myapp.sh [Install] WantedBy=multi-user.target

init

Reference:

• Chapter 13. The SUSE LINUX Boot Concept / 13.4. Init Scripts

upstart

upstart is designed to replace init, but then
upstart is replaced by systemd from ubuntu 16

• place servicename.conf under /etc/init/ which is system job.
• place servicename.conf under $HOME/.init/ which is user job.
• console log is written to /var/log/upstart/servicename.log
• it support log rotating

Run/Stop Service

#start sudo start servicename #stop sudo stop servicename

Example

author "ureshika.com" description "start and stop example for Ubuntu (upstart)" version "1.0" start on started networking stop on runlevel [!2345] setuid ubuntu setgid ubuntu # set env env APPUSER="ubuntu" env APPDIR="/usr/bin" respawn script cd $APPDIR	#use env #set env via shell script JAVA_OPTS="\ -Dcom.sun.management.jmxremote.port=8089 \ -Dcom.sun.management.jmxremote.rmi.port=8089 \ -Djava.rmi.server.hostname=localhost \ -Dcom.sun.management.jmxremote.authenticate=false \ -Dcom.sun.management.jmxremote.ssl=false \ " exec /usr/bin/java $JAVA_OPTS -jar jetty-runner.jar \ --classes "." \ --host 0.0.0.0 --port 8080 \ app.war end script

Refs

The Story Behind ‘init’ and ‘systemd’: Why ‘init’ Needed to be Replaced with ‘systemd’ in Linux