From b2472b4c49aad1362a83a2e6789c891358b854d1 Mon Sep 17 00:00:00 2001
From: Sean Danischevsky <sean@seandanischevsky.com>
Date: Sat, 16 May 2020 18:46:01 +0100
Subject: [PATCH 1/4] added -r/--retain flag

---
 src/logger.py | 9 +++++----
 src/main.py   | 4 +++-
 2 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/src/logger.py b/src/logger.py
index adf5ba5..42183bf 100644
--- a/src/logger.py
+++ b/src/logger.py
@@ -15,7 +15,7 @@
 
 
 class EnvLogger:
-    def __init__(self, client_id, host, port, username, password, prefix, use_pms5003, num_samples):
+    def __init__(self, client_id, host, port, username, password, prefix, use_pms5003, num_samples, retain):
         self.bme280 = BME280()
 
         self.prefix = prefix
@@ -33,6 +33,7 @@ def __init__(self, client_id, host, port, username, password, prefix, use_pms500
             self.pm_thread = threading.Thread(target=self.__read_pms_continuously)
             self.pm_thread.daemon = True
             self.pm_thread.start()
+        self.retain = retain
     
 
     def __on_connect(self, client, userdata, flags, rc):
@@ -89,9 +90,9 @@ def take_readings(self):
         return readings
 
 
-    def publish(self, topic, value):
+    def publish(self, topic, value, retain):
         topic = self.prefix.strip("/") + "/" + topic
-        self.client.publish(topic, str(value))
+        self.client.publish(topic, str(value), retain=retain)
 
 
     def update(self, publish_readings=True):
@@ -101,6 +102,6 @@ def update(self, publish_readings=True):
             for topic in self.samples[0].keys():
                 value_sum = sum([d[topic] for d in self.samples])
                 value_avg = value_sum / len(self.samples)
-                self.publish(topic, value_avg)
+                self.publish(topic, value_avg, retain=self.retain)
 
         self.client.loop()
diff --git a/src/main.py b/src/main.py
index 0f92baf..4a25f60 100644
--- a/src/main.py
+++ b/src/main.py
@@ -14,6 +14,7 @@ def parse_args():
     ap.add_argument("--interval", type=int, default=5, help="the duration in seconds between updates")
     ap.add_argument("--delay", type=int, default=15, help="the duration in seconds to allow the sensors to stabilise before starting to publish readings")
     ap.add_argument("--use-pms5003", action="store_true", help="if set, PM readings will be taken from the PMS5003 sensor")
+    ap.add_argument("-r", "--retain", action='store_true', help="tell MQTT broker to retain the last message")
     ap.add_argument("--help", action="help", help="print this help message and exit")
     return vars(ap.parse_args())
 
@@ -30,7 +31,8 @@ def main():
         password=args["password"],
         prefix=args["prefix"],
         use_pms5003=args["use_pms5003"],
-        num_samples=args["interval"]
+        num_samples=args["interval"],
+        retain=args["retain"],
     )
 
     # Take readings without publishing them for the specified delay period,

From 1d743e0db66b59a5b077bdf00a836b876317401d Mon Sep 17 00:00:00 2001
From: Sean Danischevsky <32126021+seaniedan@users.noreply.github.com>
Date: Sat, 16 May 2020 20:08:22 +0100
Subject: [PATCH 2/4] Update README.md

added ---retain option to docs
---
 README.md | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/README.md b/README.md
index f2aee54..25b63dd 100644
--- a/README.md
+++ b/README.md
@@ -62,6 +62,8 @@
                             stabilise before starting to publish readings
         --use-pms5003         if set, PM readings will be taken from the PMS5003
                             sensor
+        -r, --retain  tell MQTT broker to retain the last message
+ 
         --help                print this help message and exit
 
 ## Published Topics

From 9af070b34b8b9bb794cb054d41d7400c3930e80e Mon Sep 17 00:00:00 2001
From: Sean Danischevsky <32126021+seaniedan@users.noreply.github.com>
Date: Sat, 16 May 2020 20:11:25 +0100
Subject: [PATCH 3/4] Update README.md

added retain documentation
---
 README.md | 1 +
 1 file changed, 1 insertion(+)

diff --git a/README.md b/README.md
index f2aee54..7c15537 100644
--- a/README.md
+++ b/README.md
@@ -62,6 +62,7 @@
                             stabilise before starting to publish readings
         --use-pms5003         if set, PM readings will be taken from the PMS5003
                             sensor
+        -r, --retain  tell MQTT broker to retain the last message         
         --help                print this help message and exit
 
 ## Published Topics

From f4e877b4301fc026c73f96cc85993f62d9143bba Mon Sep 17 00:00:00 2001
From: Sean Danischevsky <32126021+seaniedan@users.noreply.github.com>
Date: Mon, 8 Jun 2020 06:58:04 +0100
Subject: [PATCH 4/4] Update README.md

added paho-mqtt dependency
---
 README.md | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/README.md b/README.md
index c244ec8..c01a349 100644
--- a/README.md
+++ b/README.md
@@ -11,7 +11,11 @@
 
        sudo git clone https://github.com/hotplot/enviroplus-mqtt /usr/src/enviroplus-mqtt
 
-5) Add a new file at `/etc/systemd/system/envlogger.service` with the following content:
+5) Install [Paho MQTT tools](https://www.eclipse.org/paho/):
+
+       pip3 install paho-mqtt
+
+6) Add a new file at `/etc/systemd/system/envlogger.service` with the following content:
 
        [Unit]
        Description=Enviro+ MQTT Logger