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asyncio-mqtt

Idiomatic asyncio wrapper around paho-mqtt

    0.16.2

Maintainers
3

Readme

Idiomatic asyncio MQTT Client 🙌

License: BSD-3-Clause PyPI version Supported Python versions PyPI downloads Coverage Coverage pre-commit.ci status Typing: strict Code Style: Black

Write code like this:

Subscriber

async with Client("test.mosquitto.org") as client:
    async with client.messages() as messages:
        await client.subscribe("humidity/#")
        async for message in messages:
            print(message.payload)

Publisher

async with Client("test.mosquitto.org") as client:
    await client.publish("humidity/outside", payload=0.38)

asyncio-mqtt combines the stability of the time-proven paho-mqtt library with a modern, asyncio-based interface.

  • No more callbacks! 👍
  • No more return codes (welcome to the MqttError)
  • Graceful disconnection (forget about on_unsubscribe, on_disconnect, etc.)
  • Compatible with async code
  • Fully type-hinted
  • Did we mention no more callbacks?

The whole thing is less than 700 lines of code.

Contents 🔍

Installation 📚

asyncio-mqtt can be installed via pip install asyncio-mqtt. It requires Python 3.7+ to run. The only dependency is paho-mqtt.

If you can't wait for the latest version and want to install directly from GitHub, use:

pip install git+https://github.com/sbtinstruments/asyncio-mqtt

Note for Windows users

Since Python 3.8, the default asyncio event loop is the ProactorEventLoop. Said loop doesn't support the add_reader method that is required by asyncio-mqtt. Please switch to an event loop that supports the add_reader method such as the built-in SelectorEventLoop:

# Change to the "Selector" event loop
asyncio.set_event_loop_policy(asyncio.WindowsSelectorEventLoopPolicy())
# Run your async application as usual
asyncio.run(main())

Advanced usage ⚡

Let's make the example from before more interesting:

Configuring the client

You can configure quite a few things when initializing the client. These are all the possible parameters together with their default values. See paho-mqtt's documentation for more information about the individual parameters.

import asyncio_mqtt as aiomqtt
import paho.mqtt as mqtt


aiomqtt.Client(
    hostname="test.mosquitto.org",  # The only non-optional parameter
    port=1883,
    username=None,
    password=None,
    logger=None,
    client_id=None,
    tls_context=None,
    tls_params=None,
    proxy=None,
    protocol=None,
    will=None,
    clean_session=None,
    transport="tcp",
    keepalive=60,
    bind_address="",
    bind_port=0,
    clean_start=mqtt.client.MQTT_CLEAN_START_FIRST_ONLY,
    properties=None,
    message_retry_set=20,
    socket_options=(),
    max_concurrent_outgoing_calls=None,
    websocket_path=None,
    websocket_headers=None,
)

Filtering messages

Imagine you're measuring temperature and humidity on the outside and inside, and our topics look like this: temperature/outside. You want to receive all types of measurements but handle them differently. asyncio-mqtt provides Topic.matches() to make this easy:

import asyncio
import asyncio_mqtt as aiomqtt


async def main():
    async with aiomqtt.Client("test.mosquitto.org") as client:
        async with client.messages() as messages:
            await client.subscribe("#")
            async for message in messages:
                if message.topic.matches("humidity/outside"):
                    print(f"[humidity/outside] {message.payload}")
                if message.topic.matches("+/inside"):
                    print(f"[+/inside] {message.payload}")
                if message.topic.matches("temperature/#"):
                    print(f"[temperature/#] {message.payload}")


asyncio.run(main())

Note that in our example, messages to temperature/inside are handled twice!

Sharing the connection

In many cases, you'll want to send and receive messages in different locations in your code. You could create a new client each time, but

  1. this is not very performant, and
  2. you'll use a lot more network bandwidth.

You can share the connection by passing the Client instance to all functions that need it:

import asyncio
import asyncio_mqtt as aiomqtt


async def publish_humidity(client):
    await client.publish("humidity/outside", payload=0.38)


async def publish_temperature(client):
    await client.publish("temperature/outside", payload=28.3)


async def main():
    async with aiomqtt.Client("test.mosquitto.org") as client:
        await publish_humidity(client)
        await publish_temperature(client)


asyncio.run(main())
Side by side with web frameworks

Most web frameworks take control over the "main" function, which makes it difficult to figure out where to create and connect the Client and how to share this connection.

Some frameworks like Starlette directly support lifespan context managers, with which you can safely set up a global client instance that you can then pass to functions that need it, just like before:

import asyncio
import asyncio_mqtt as aiomqtt
import starlette.applications
import contextlib


client = None


@contextlib.asynccontextmanager
async def lifespan(app):
    global client
    async with aiomqtt.Client("test.mosquitto.org") as c:
        client = c
        yield


app = starlette.applications.Starlette(
    routes=[],
    lifespan=lifespan,
)

FastAPI (which is built upon Starlette) doesn't expose that API yet, but there are multiple open PRs to add it. In the meantime, you can work around it via FastAPI's dependency injection.

Why can't I connect/disconnect manually?

Managing a connection by calling connect and disconnect directly is a bit tricky. For example, when you're disconnecting the client, you'd have to make sure that there's no other task that still relies on the connection. There are many similar situations where something can easily go wrong.

Context managers take care of all connection and disconnection logic for you, in a way that makes it very difficult to shoot yourself in the foot. They are a lot easier and less error-prone to use than connect/disconnect.

Supporting both context managers and manual connect/disconnect would add a lot of complexity to asyncio-mqtt. To keep maintainer burden manageable, we focus only on the preferred option: context managers.

Listening without blocking

If you run the basic example for subscribing and listening for messages, you'll notice that the program doesn't finish until you stop it. Waiting for messages blocks the execution of everything that comes afterwards. If you want to run other code after starting your listener (e.g. handling HTTP requests in a web framework) you don't want this.

To solve this, you can use asyncio's create_task without awaiting the created task. The concept is similar to starting a new thread without joining it in a multithreaded application.

import asyncio
import asyncio_mqtt as aiomqtt


async def listen():
    async with aiomqtt.Client("test.mosquitto.org") as client:
        async with client.messages() as messages:
            await client.subscribe("humidity/#")
            async for message in messages:
                print(message.payload)


async def main():
    # Wait for messages in (unawaited) asyncio task
    loop = asyncio.get_event_loop()
    task = loop.create_task(listen())
    # This will still run!
    print("Magic!")
    # If you don't await the task here the program will simply finish.
    # However, if you're using an async web framework you usually don't have to await
    # the task, as the framework runs in an endless loop.
    await task


asyncio.run(main())

Reconnecting

You can reconnect when the connection to the broker is lost by wrapping your code in a try/except-block and listening for MqttErrors.

import asyncio
import asyncio_mqtt as aiomqtt


async def main():
    reconnect_interval = 5  # In seconds
    while True:
        try:
            async with aiomqtt.Client("test.mosquitto.org") as client:
                async with client.messages() as messages:
                    await client.subscribe("humidity/#")
                    async for message in messages:
                        print(message.payload.decode())
        except aiomqtt.MqttError as error:
            print(f'Error "{error}". Reconnecting in {reconnect_interval} seconds.')
            await asyncio.sleep(reconnect_interval)



asyncio.run(main())

TLS

You can configure TLS via the TLSParameters class. The parameters are directly passed through to paho-mqtt's tls_set function. See paho-mqtt's documentation for more information about the individual parameters.

import asyncio
import asyncio_mqtt as aiomqtt
import ssl


tls_params = aiomqtt.TLSParameters(
    ca_certs=None,
    certfile=None,
    keyfile=None,
    cert_reqs=ssl.CERT_REQUIRED,
    tls_version=ssl.PROTOCOL_TLS,
    ciphers=None,
)


async def main():
    async with aiomqtt.Client("test.mosquitto.org", tls_params=tls_params) as client:
        await client.publish("humidity/outside", payload=0.38)


asyncio.run(main())

Proxying

You can configure proxying via the ProxySettings class. The parameters are directly passed through to paho-mqtt's proxy_set functionality. Both SOCKS and HTTP proxies are supported. Note that proxying is an extra feature (even in paho-mqtt) that requires the PySocks dependency. See paho-mqtt's documentation for more information about the individual parameters.

import asyncio
import asyncio_mqtt as aiomqtt
import socks


proxy_params = aiomqtt.ProxySettings(
    proxy_type=socks.HTTP,
    proxy_addr="www.example.com",
    proxy_rdns=True,
    proxy_username=None,
    proxy_password=None,
)

async def main():
    async with aiomqtt.Client("test.mosquitto.org", proxy=proxy_params) as client:
        await client.publish("humidity/outside", payload=0.38)


asyncio.run(main())

License 📋

License: BSD-3-Clause

Note that the underlying paho-mqtt library is dual-licensed. One of the licenses is the so-called Eclipse Distribution License v1.0. It is almost word-for-word identical to the BSD 3-clause License. The only differences are:

  • One use of "COPYRIGHT OWNER" (EDL) instead of "COPYRIGHT HOLDER" (BSD)
  • One use of "Eclipse Foundation, Inc." (EDL) instead of "copyright holder" (BSD)

Versioning 🎯

PyPI

This project adheres to Semantic Versioning.

Expect API changes until we reach version 1.0.0. After 1.0.0, breaking changes will only occur in major release (e.g., 2.0.0, 3.0.0, etc.).

Changelog 🚧

Please refer to the CHANGELOG document. It adheres to the principles of Keep a Changelog.

Is asyncio-mqtt not what you are looking for? Try another client:

  • paho-mqtt — Own protocol implementation. Synchronous.
    GitHub stars license
  • gmqtt — Own protocol implementation. Asynchronous.
    GitHub stars license
  • fastapi-mqtt — Asynchronous wrapper around gmqtt. Simplifies integration in your FastAPI application.
    GitHub stars license
  • amqtt — Own protocol implementation. Asynchronous. Includes a broker.
    GitHub stars license
  • mqttools — Own protocol implementation. Asynchronous.
    GitHub stars license
  • trio-paho-mqtt — Asynchronous wrapper around paho-mqtt (similar to asyncio-mqtt). Based on trio instead of asyncio.
    GitHub stars license

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