From: Jonathan McDowell <noodles@earth.li>
Date: Mon, 21 Sep 2020 20:18:57 +0000 (+0100)
Subject: Resubscribe to MQTT prefix when reconnecting
X-Git-Url: https://the.earth.li/gitweb/?p=energenie-attiny.git;a=commitdiff_plain;h=05ee67a050dd758773efde0bfd28e3a2eb8687d6;hp=96d1571590812770023026aed69ca6d4c948d44d

Resubscribe to MQTT prefix when reconnecting
---

diff --git a/mqtt-power b/mqtt-power
index d2723cb..f74a337 100755
--- a/mqtt-power
+++ b/mqtt-power
@@ -62,6 +62,15 @@ def mqtt_message(client, device, message):
     control_relay(device, relay, state)
 
 
+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]))
@@ -94,10 +103,10 @@ client.tls_set(ca_certs='/etc/ssl/certs/ca-certificates.crt')
 client.username_pw_set(auth['username'], auth['password'])
 client.user_data_set(relay)
 client.on_message = mqtt_message
+client.on_connect = mqtt_connect
 client.connect(Broker, port=8883)
-print("Subscribing to %s" % prefix.format(serno_str))
-client.subscribe(prefix.format(serno_str))
 client.loop_start()
+client.will_set("relay/{}/LWT".format(serno_str), "Offline", retain=True)
 
 while True:
     state = {