Script to update an ipv4/ipv6 dns record with your ip at hosting.de using their api for a free dynamic dns solution instead of paying for their service

ddns-update.sh

#!/usr/bin/env bash

set -euo pipefail

readonly APIKEY='$$YOUR API KEY$$'
readonly ENDPOINT='https://secure.hosting.de'
readonly ZONE='$$YOUR DOMAIN$$'
readonly RECORD='$$YOUR SUBDOMAIN$$'

# Record IDs for some reason required even though documentation says optional if name is given
readonly IPV4ID='asd1'
readonly IPV6ID='asd2'

_contains() {
	local str="$1"
	local sub="$2"
	echo "$str" | grep -- "$sub" >/dev/null 2>&1
}

_post() {
	local body="$1"
	local post_url="$2"
	local httpmethod="${3:-}"
	local postContentType="${4:-}"

	if [ -z "$httpmethod" ]; then
		httpmethod="POST"
	fi

	if [ -z "$postContentType" ]; then
		postContentType="application/json"
	fi

	local response=$(curl -sS -X $httpmethod -H "Content-Type: $postContentType" --data "$body" "$post_url")

	local ret="$?"

	printf "%s" "$response"
	return $ret
}

cachedir="${XDG_CACHE_HOME:-$HOME/.cache}/ddns-update"
mkdir -p "${cachedir}"

cached_ipv4_file="${cachedir}/ipv4"
cached_ipv6_file="${cachedir}/ipv6"

[[ -f "$cached_ipv4_file" ]] && cached_ipv4="$(<$cached_ipv4_file)" || cached_ipv4=""
[[ -f "$cached_ipv6_file" ]] && cached_ipv6="$(<$cached_ipv6_file)" || cached_ipv6=""

current_ipv4=$(dig +short +tls -4 +timeout=5 +tries=1 @dns.opendns.com A myip.opendns.com)
current_ipv6=$(dig +short +tls -6 +timeout=5 +tries=1 @dns.opendns.com AAAA myip.opendns.com)

declare -a records
update=false

if [ "$cached_ipv4" != "$current_ipv4" ]; then
	echo "Updating ipv4 record..."
	echo "$current_ipv4" > "$cached_ipv4_file"
	records+=("{\"id\":\"${IPV4ID}\",\"name\":\"${RECORD}\",\"type\":\"A\",\"content\":\"${current_ipv4}\",\"comments\":\"DDNS Last Modified: $(date +"%Y-%m-%dT%H:%M:%S%z")\",\"ttl\":60}")
	update=true
fi

if [ "$cached_ipv6" != "$current_ipv6" ]; then
	echo "Updating ipv6 record..."
	echo "$current_ipv6" > "$cached_ipv6_file"
	records+=("{\"id\":\"${IPV6ID}\",\"name\":\"${RECORD}\",\"type\":\"AAAA\",\"content\":\"${current_ipv6}\",\"comments\":\"DDNS Last Modified: $(date +"%Y-%m-%dT%H:%M:%S%z")\",\"ttl\":60}")
	update=true
fi

if [ $update = true ]; then
	records_list=$(printf "%s," "${records[@]}" | sed 's/,$//')
	data="{\"authToken\":\"${APIKEY}\",\"zoneName\":\"${ZONE}\",\"recordsToModify\":[${records_list}]}"
	result=$(_post "${data}" "${ENDPOINT}/api/dns/v1/json/recordsUpdate")

	if _contains "$result" '"status": "error"'; then
		if _contains "$result" '"code": 10109'; then
			echo "The API-Key is invalid or could not be found"
			exit 2
		else
			echo "UNKNOWN API ERROR"
			exit 3
		fi
		exit 1
	fi

	echo "Updated"
fi

exit 0