Adopt new hierarchy pattern

services/ddclient/volumes/data/.gitignore

@@ -0,0 +1 @@
+!postscript_gotify.sh

services/ddclient/volumes/data/postscript_gotify.sh

@@ -0,0 +1,12 @@
+#!/bin/bash
+
+if [ "$(cat /data/gotify_previous_ip || true)" != "$1" ]; then
+    echo -n "$1" > /data/gotify_previous_ip
+
+    curl -s "${GOTIFY_ADDRESS%/}/message" \
+        -X POST \
+        -H "X-Gotify-Key: $GOTIFY_TOKEN" \
+        -F "title=IP Address updated" \
+        -F "message=IP address detected as $1" \
+        -F "priority=5"
+fi

services/ddclient/volumes/init/.gitignore

@@ -0,0 +1 @@
+!entrypoint.sh

services/ddclient/volumes/init/entrypoint.sh

@@ -0,0 +1,29 @@
+#!/bin/bash
+
+# usage: file_env VAR [DEFAULT]
+#    ie: file_env 'XYZ_DB_PASSWORD' 'example'
+# (will allow for "$XYZ_DB_PASSWORD_FILE" to fill in the value of
+#  "$XYZ_DB_PASSWORD" from a file, especially for Docker's secrets feature)
+file_env() {
+	local var="$1"
+	local fileVar="${var}_FILE"
+	local def="${2:-}"
+	if [ "${!var:-}" ] && [ "${!fileVar:-}" ]; then
+		mysql_error "Both $var and $fileVar are set (but are exclusive)"
+	fi
+	local val="$def"
+	if [ "${!var:-}" ]; then
+		val="${!var}"
+	elif [ "${!fileVar:-}" ]; then
+		val="$(< "${!fileVar}")"
+	fi
+	export "$var"="$val"
+	unset "$fileVar"
+}
+
+apk add --update gettext
+
+file_env 'GOTIFY_TOKEN'
+file_env 'CLOUDFLARE_TOKEN'
+
+envsubst < /config/ddclient.conf.tpl > /ddclient.conf