Script for Dynamic IP with Rancher Agent (v1.6)

DynamicIP.sh

#!/bin/bash
# https://rancher.com/docs/rancher/v1.6/en/faqs/agents/#how-does-the-host-determine-ip-address-and-how-can-i-change-it-what-do-i-do-if-the-ip-of-my-host-has-changed-due-to-reboot

LOCATION="/tmp/ip.txt"
RANCHER_URL=""

function getIPAndSave() {
	ip=$(curl -s https://api-ipv4.ip.sb/ip)
	rc=$?
	if [ "$rc" != "0" ]; then
		echo "curl exit with non 0, exiting"
		exit $?
	fi
	echo "My IP address is: $ip"
    	echo "Saving to temp file..."
	echo "$ip" > $LOCATION
}

function runRancherRegister() {
    docker run -e CATTLE_AGENT_IP="$1"  --rm --privileged -v /var/run/docker.sock:/var/run/docker.sock -v /var/lib/rancher:/var/lib/rancher rancher/agent:v1.2.11 $RANCHER_URL
}

# Check existing file and ip

if [ ! -f $LOCATION ]; then
    echo "File not found!"
    echo "Run IP Process"
    getIPAndSave
    echo "Wait for next Call..."
else
    read -r previousIP < $LOCATION
    echo "Acquire previous IP: $previousIP"
    getIPAndSave
    read -r currentIP < $LOCATION
    if [ "$previousIP" = "$currentIP" ]; then
        echo "IP does not changed, exit and wait for next call..."
    else 
        echo "IP changed, start re-register process"
        runRancherRegister $currentIP
        echo "finished, wait for next call..."
    fi
fi