HOWTO: Add loopback as a service

This can be easily done by adding an "ip" command to system startup with RHEL8 "systemctl".

1. Create a run script for ip to setup a loopback device on 192.168.10.1:

echo 'ip addr add 192.168.10.1/24 dev lo' >/usr/local/sbin/loopback2.sh
chmod 700 /usr/local/sbin/loopback2.sh


2. Create the service file:

vi /lib/systemd/system/loopback2.service
or
systemctl edit loopback2


2. Have it start as service with systemctl:


[Unit]
after=network

[Service]
ExecStart=/usr/local/sbin/loopback2.sh

[Install]
WantedBy=default.target


3. Enable and auto start:

systemctl enable loopback2.service
systemctl start loopback2.service


4. Confirm the setup:

ip addr
systemctl status loopback2