Locust如何测试物联网MQTT

Posted 2021-12-15 SummerStone

MQTT是干什么的

简单来说，它是物联网的通信协议，是消息通道建立，消息发送和消息订阅的标准。如果大家想了解更多概念上的详细可以网上搜索。

Locust测试MQTT的步骤

测试步骤，可以用以下图形表示：

准备环境，安装Locust测试环境

这个比较简单，主要是准备好Python的虚拟开发环境，并安装好locust的python软件包。可以在Locust官方网站找到相关步骤，这里不再赘述。

安装MQTT客户端库 paho-mqtt

可以在Python虚拟环境，执行如下安装命令：

pip install paho-mqtt

locustfile中首先实现消息发送

这里为了简单起见，使用公共的MQTT broker： EMQX, 它的地址为："

broker.emqx.io"

具体实现的代码如下：

broker_add = broker.emqx.io
port = 1883
topic = "/python/mqtt_topic_for_python"

client_id = f"python-mqtt-random.randint(0,100)"

def connect_mqtt():
    def on_connect(client,userdata,flags,rc):
        if rc == 0:
            print("Connected to MQTT Broker!")
        else:
            print("Failed to connect, return code %d\\n",rc)

    client = mqtt_c.Client(client_id)
    client.on_connect= on_connect
    client.connect(broker_add,port)

    return client

def publish(client):
    msg_count = 0
    while True:
        time.sleep(3)
        msg = f"message: msg_count"
        result = client.publish(topic,msg)
        status = result[0]
        if status == 0:
            print(f"send `msg` to topic `topic` ")
        else:
            print(f"Failed to send message to topic topic")
        msg_count += 1

def run():
    client = connect_mqtt()
    client.loop_start()
    publish(client)

完善locustfile中关于Taskset和User的相关配置

具体如下代码，所以会发现，用Python-Locust去测试非HTTP协议的应用系统还是比较方便的，代码即测试。

class TheTaskSet(TaskSet):
    @task
    def task_1(self):
        run()


class TheUser(User):
    tasks = [TheTaskSet]
    wait_time = constant_pacing(1)

完整的locustfile如下：

import random,time

from paho.mqtt import client as mqtt_c
from locust import TaskSet,task,User,constant_pacing

broker_add = broker.emqx.io
port = 1883
topic = "/python/mqtt_topic_for_python"

client_id = f"python-mqtt-random.randint(0,100)"

def connect_mqtt():
    def on_connect(client,userdata,flags,rc):
        if rc == 0:
            print("Connected to MQTT Broker!")
        else:
            print("Failed to connect, return code %d\\n",rc)

    client = mqtt_c.Client(client_id)
    client.on_connect= on_connect
    client.connect(broker_add,port)

    return client

def publish(client):
    msg_count = 0
    while True:
        time.sleep(3)
        msg = f"message: msg_count"
        result = client.publish(topic,msg)
        status = result[0]
        if status == 0:
            print(f"send `msg` to topic `topic` ")
        else:
            print(f"Failed to send message to topic topic")
        msg_count += 1

def run():
    client = connect_mqtt()
    client.loop_start()
    publish(client)


class TheTaskSet(TaskSet):
    @task
    def task_1(self):
        run()


class TheUser(User):
    tasks = [TheTaskSet]
    wait_time = constant_pacing(1)

具体的执行结果如下：

Connected to MQTT Broker!
send `message: 0` to topic `/python/mqtt_topic_for_python` 
send `message: 1` to topic `/python/mqtt_topic_for_python` 
send `message: 2` to topic `/python/mqtt_topic_for_python` 
send `message: 3` to topic `/python/mqtt_topic_for_python` 
send `message: 4` to topic `/python/mqtt_topic_for_python` 
send `message: 5` to topic `/python/mqtt_topic_for_python` 
...

参考文档：EMQ官方文档，https://www.emqx.com/zh/blog/how-to-use-mqtt-in-python