Adds MQTT backend

.github/workflows/test-suite.yml

@@ -51,6 +51,11 @@ jobs:
           POSTGRES_USER: postgres
         ports:
         - 5432:5432
+      mqtt:
+        image: "eclipse-mosquitto"
+        ports:
+          - 1883:1883
+        options: --hostname mqtt mosquitto -c /mosquitto-no-auth.conf
 
     steps:
       - uses: "actions/checkout@v2"

README.md

@@ -3,7 +3,7 @@
 Broadcaster helps you develop realtime streaming functionality by providing
 a simple broadcast API onto a number of different backend services.
 
-It currently supports [Redis PUB/SUB](https://redis.io/topics/pubsub), [Apache Kafka](https://kafka.apache.org/), and [Postgres LISTEN/NOTIFY](https://www.postgresql.org/docs/current/sql-notify.html), plus a simple in-memory backend, that you can use for local development or during testing.
+It currently supports [Redis PUB/SUB](https://redis.io/topics/pubsub), [Apache Kafka](https://kafka.apache.org/), and [Postgres LISTEN/NOTIFY](https://www.postgresql.org/docs/current/sql-notify.html), [MQTT](https://mqtt.org/) plus a simple in-memory backend, that you can use for local development or during testing.
 
 <img src="https://raw.githubusercontent.com/encode/broadcaster/master/docs/demo.gif" alt='WebSockets Demo'>
 
@@ -73,13 +73,15 @@ Python 3.7+
 * `pip install broadcaster[redis]`
 * `pip install broadcaster[postgres]`
 * `pip install broadcaster[kafka]`
+* `pip install broadcaster[mqtt]`
 
 ## Available backends
 
 * `Broadcast('memory://')`
 * `Broadcast("redis://localhost:6379")`
 * `Broadcast("postgres://localhost:5432/broadcaster")`
 * `Broadcast("kafka://localhost:9092")`
+* `Broadcast("mqtt://localhost:1883")`
 
 ## Where next?
 

broadcaster/_backends/mqtt.py

@@ -0,0 +1,44 @@
+import typing
+from contextlib import AsyncExitStack
+from urllib.parse import urlparse
+
+import asyncio_mqtt
+
+from .._base import Event
+from .base import BroadcastBackend
+
+
+class MqttBackend(BroadcastBackend):
+    def __init__(self, url: str):
+        parsed_url = urlparse(url)
+        self._host = parsed_url.hostname or "localhost"
+        self._port = 8883 if parsed_url.scheme == "mqtts" else 1883
+        self._port = parsed_url.port or self._port
+
+    async def connect(self) -> None:
+        self.stack = AsyncExitStack()
+
+        self.client = asyncio_mqtt.Client(self._host, port=self._port)
+        self.messages = self.client.filtered_messages("#")
+
+        self.client = await self.stack.enter_async_context(self.client)
+        self.messages = await self.stack.enter_async_context(self.messages)
+
+    async def disconnect(self) -> None:
+        await self.stack.aclose()
+
+    async def subscribe(self, channel: str) -> None:
+        await self.client.subscribe(channel)
+
+    async def unsubscribe(self, channel: str) -> None:
+        await self.client.unsubscribe(channel)
+
+    async def publish(self, channel: str, message: typing.Any) -> None:
+        await self.client.publish(channel, message, retain=False)
+
+    async def next_published(self) -> Event:
+        async for message in self.messages:
+            event = Event(channel=message.topic, message=message.payload)
+            break
+
+        return event

broadcaster/_base.py

@@ -51,6 +51,11 @@ def __init__(self, url: str):
 
             self._backend = MemoryBackend(url)
 
+        elif parsed_url.scheme in ("mqtt", "mqtts"):
+            from ._backends.mqtt import MqttBackend
+
+            self._backend = MqttBackend(url)
+
     async def __aenter__(self) -> "Broadcast":
         await self.connect()
         return self

docker-compose.yaml

@@ -36,3 +36,10 @@ services:
       - POSTGRES_USER=postgres
     ports:
       - 5432:5432
+  mqtt:
+    image: "eclipse-mosquitto"
+    hostname: mqtt
+    command: mosquitto -c /mosquitto-no-auth.conf
+    ports:
+      - 1883:1883
+

example/README.md

@@ -22,3 +22,4 @@ In order to run the app with different backends, you have to set the env
 | kafka    | `export BROADCAST_URL=kafka://localhost:9092`                | `docker-compose up kafka`    |
 | redis    | `export BROADCAST_URL=redis://localhost:6379`                | `docker-compose up redis`    |
 | postgres | `export BROADCAST_URL=postgres://localhost:5432/broadcaster` | `docker-compose up postgres` |
+| mqtt     | `export BROADCAST_URL=mqtt://localhost:1883`                 | `docker-compose up mqtt`     |

example/requirements.txt

@@ -1,4 +1,4 @@
 uvicorn
 starlette
 jinja2
-broadcaster[redis,postgres,kafka]
+broadcaster[redis,postgres,kafka,mqtt]

requirements.txt

@@ -1,4 +1,4 @@
--e .[redis,postgres,kafka]
+-e .[redis,postgres,kafka,mqtt]
 
 # Documentation
 mkdocs==1.3.1

scripts/docker/mqtt/mosquitto-no-auth.conf

@@ -0,0 +1,5 @@
+# This is a Mosquitto configuration file that creates a listener on port 1883
+# that allows unauthenticated access.
+
+listener 1883
+allow_anonymous true

scripts/start

@@ -1,12 +1,13 @@
 #!/bin/sh -e
-# Accepted values: postgres, kafka, redis
+# Accepted values: postgres, kafka, redis, mqtt
 # If no variable provided all services will start
 if [ -n "$1" ]; then
-    if [ "$1" != "kafka" ] && [ "$1" != "redis" ] && [ "$1" != "postgres" ]; then
+    if [ "$1" != "kafka" ] && [ "$1" != "redis" ] && [ "$1" != "postgres" ] && [ "$1" != "mqtt" ]; then
         echo  "Not a valid value. Choose one or none:
     kafka
     redis
-    postgres ";
+    postgres
+    mqtt ";
         exit 1;
     fi
 fi

setup.py

@@ -49,6 +49,7 @@ def get_packages(package):
         "redis": ["asyncio-redis"],
         "postgres": ["asyncpg"],
         "kafka": ["aiokafka"],
+        "mqtt": ["asyncio-mqtt"],
         "test": ["pytest", "pytest-asyncio"],
     },
     classifiers=[

tests/test_broadcast.py

@@ -44,3 +44,13 @@ async def test_kafka():
             event = await subscriber.get()
             assert event.channel == "chatroom"
             assert event.message == "hello"
+
+
+@pytest.mark.asyncio
+async def test_mqtt():
+    async with Broadcast("mqtt://localhost:1883") as broadcast:
+        async with broadcast.subscribe("chatroom") as subscriber:
+            await broadcast.publish("chatroom", "hello")
+            event = await subscriber.get()
+            assert event.channel == "chatroom"
+            assert event.message == b"hello"