+def mqtt_connect(client, userdata, flags, rc):
+ if debug:
+ print("Connected to MQTT server")
+
+ client.publish("relay/{}/LWT".format(serno_str), "Online", retain=True)
+ print("Subscribing to %s" % prefix.format(serno_str))
+ client.subscribe(prefix.format(serno_str))
+
+
+def uptime():
+ with open('/proc/uptime', 'r') as f:
+ seconds = int(float(f.readline().split()[0]))
+
+ days = seconds // 86400
+ seconds %= 86400
+ hours = seconds // 3600
+ seconds %= 3600
+ minutes = seconds // 60
+ seconds %= 60
+
+ return "{}T{}:{}:{}".format(days, hours, minutes, seconds)
+