systemd: add units for a service and timer

Signed-off-by: Vincent Batts <vbatts@hashbangbash.com>

README.md

@@ -64,3 +64,9 @@ Whether you use a cronjob or a systemd timer, you can chain this command to a da
 ```shell
 too-soon pem "fullchain.pem" || mail -s "$(shell hostname): certificates expire soon" webmaster@example.com
 ```
+
+## `systemd` units
+
+Copy the `too-soon-remote@.service` and `too-soon-remote@.timer` to `/etc/systemd/system/` after making sure the path to the `too-soon` binary is correct (preset as `/usr/local/bin/too-soon`).
+Then `systemct enable --now too-soon-remote@example.com.timer`.
+

too-soon-remote@.service

@@ -0,0 +1,5 @@
+[Unit]
+Description=check domain's certificate expiration and alert if expires within 20d
+
+[Service]
+ExecStart="/usr/local/bin/too-soon" "-D" "remote" "%i"

too-soon-remote@.timer

@@ -0,0 +1,10 @@
+[Unit]
+Description=check domain's certificate expiration and alert if expires within 20d
+
+[Timer]
+OnCalendar=*-*-* 6:00
+RemainAfterElapse=no
+
+[Install]
+WantedBy=timers.target
+