alertmanager service using rkt

alertmanager.service

[Unit]
Description=alertmanager
Requires=network-online.target
After=network-online.target

[Service]
Slice=machine.slice
Delegate=true
ExecStartPre=/usr/bin/rkt fetch quay.io/prometheus/alertmanager:latest
ExecStart=/usr/bin/rkt run --net=host --volume volume-alertmanager,kind=host,source=/srv/mon/alertmanager,readOnly=false --mount volume=volume-alertmanager,target=/etc/alertmanager --volume resolv,kind=host,source=/etc/resolv.conf,readOnly=true --mount volume=resolv,target=/etc/resolv.conf quay.io/prometheus/alertmanager:latest
ExecStopPost=/usr/bin/rkt gc --mark-only
KillMode=mixed
Restart=always