Hetzner simple Failover Script

failover.sh

#!/bin/bash

#------------------------------------------------------------
# title           :failover.sh
# description     :This script will call hetzner failover api
# author          :Sebastian Reimers <support@miete-admin.de>
# date            :18.02.2016
# version         :0.1 
#------------------------------------------------------------
# settings

hlogin=""
hpassword=""
hserver="https://robot-ws.your-server.de/failover"
failoverip=""

#------------------------------------------------------------

lhost=$(cat /tmp/failover_last)
chost=$(curl http://10.10.1.1/host.html 2>/dev/null)

if [ "$lhost" != "$chost" ]; then
        echo "$lhost != $chost"
        curl -u $hlogin:$hpassword $hserver/$failoverip -d active_server_ip=$chost
        echo $chost > /tmp/failover_last
fi

I would suggest getting the variable lhost from hetzner:

lhost=$(curl -s -u $hlogin:$hpassword $hserver/$failoverip | jq -r '.failover.active_server_ip')

This would work on a freshly booted machine where nothing is in /tmp.