A fresh install of varnish can not start.

service varnish start

systemd[1]: varnish.service: Failed to load environment files: No such file or
directory
systemd[1]: varnish.service: Failed to run 'start' task: No such file or
directory
systemd[1]: Failed to start Varnish HTTP accelerator/reverse proxy.

Here is the default content of /usr/lib/systemd/system/varnish.service

[Unit]
Description=Varnish HTTP accelerator/reverse proxy
After=network.target

[Service]
EnvironmentFile=/etc/sysconfig/varnish
PIDFile=/var/run/varnishd.pid
ExecStart=/usr/sbin/varnishd $VARNISHD_PARAMS -P /var/run/varnishd.pid -F
[Install]
WantedBy=multi-user.target


/etc/sysconfig/varnish does not exist
touch /etc/sysconfig/varnish is sufficient.
By the way, i don't know yet if nothing is missing to varnish later.
As an example, i don't know where is initialized this $varnishd_params too