Create a service from a script by using systemd

Create the startup script "run.sh" and place it in a directory at the same level as "es-agent."

The content of the startup script is as follows:

#!/bin/sh

BIN_DIR=/opt/edge
COMMAND=${BIN_DIR}/es-agent

cd $BIN_DIR
exec $COMMAND run -c ${BIN_DIR}/es-agent.yaml

exit 0

Allow run.sh to be executed.

$ chmod +x run.sh

Modify the unit file "es-agent.service."

The content of the file is as follows:

[Unit]
Description=es-agent
ConditionPathExists=/opt/edge

[Service]
Type=simple
ExecStart=/opt/edge/run.sh
ExecStop=/bin/kill -TERM ${MAINPID}
Restart=always

[Install]
WantedBy=multi-user.target

Place the unit file "es-agent.service" in the "/etc/systemd/system" directory.

# cp es-agent.service /etc/systemd/system

Notify systemd that the unit file has been added or modified.

# systemctl daemon-reload

# systemctl status es-agent.service
es-agent.service - es-agent
Loaded: loaded (/etc/systemd/system/es-agent.service; disabled)
Active: inactive (dead)

Configure settings for automatic startup of es-agent.

# systemctl enable es-agent.service
ln -s '/etc/systemd/system/es-agent.service' '/etc/systemd/system/multi-user.target.wants/es-agent.service'
 
# systemctl status es-agent.service
es-agent.service - es-agent
Loaded: loaded (/etc/systemd/system/es-agent.service; enabled)
Active: inactive (dead)

es-agent is now set to start up automatically when the IoT gateway OS starts. Confirm once more that the settings have been configured correctly.

Start the service with "systemctl start <service name>" and confirm the status and content of standard output with "systemctl status <service name>".

If an error is not output at this time, the service has been created from the script correctly, and has been started.

# systemctl start es-agent.service

# systemctl status es-agent.service
● es-agent.service - es-agent
   Loaded: loaded (/etc/systemd/system/es-agent.service; enabled)
   Active: active (running) since Tue 2020-02-25 06:00:39 CET; 7s ago
  Process: 1577 ExecStop=/bin/kill -TERM ${MAINPID} (code=exited, status=0/SUCCESS)
 Main PID: 1661 (es-agent)
   CGroup: /system.slice/es-agent.service
           └─1661 /opt/edge/es-agent run -c /opt/edge/es-agent.yaml

Feb 25 06:00:39 debian run.sh[1661]: time="2020-02-25T05:00:39Z" level=info msg="no plugins to load" file=loade...script
Feb 25 06:00:39 debian run.sh[1661]: time="2020-02-25T05:00:39Z" level=info msg="Starting the server on :15601"
Feb 25 06:00:39 debian run.sh[1661]: {"cpu":99.99999999779732,"disk_avail":14.960063934326172}
Feb 25 06:00:40 debian run.sh[1661]: {"cpu":0,"disk_avail":14.960063934326172}
Feb 25 06:00:41 debian run.sh[1661]: {"cpu":0,"disk_avail":14.960063934326172}
Feb 25 06:00:42 debian run.sh[1661]: {"cpu":0.9900990099009309,"disk_avail":14.960063934326172}
Feb 25 06:00:43 debian run.sh[1661]: {"cpu":0,"disk_avail":14.960063934326172}
Feb 25 06:00:44 debian run.sh[1661]: {"cpu":0,"disk_avail":14.960063934326172}
Feb 25 06:00:45 debian run.sh[1661]: {"cpu":0,"disk_avail":14.960063934326172}
Feb 25 06:00:46 debian run.sh[1661]: {"cpu":0,"disk_avail":14.960063934326172}