使用 Docker 搭建 EMQX，并通过 MicroPython 实现 MQTT 控制 ESP32 LED

在物联网项目中，MQTT 是最常用的消息通信协议之一。本文将通过一个完整示例，演示如何：

使用 Docker 快速部署 EMQX
解决端口冲突问题
使用 MicroPython 作为 MQTT 客户端
通过 MQTT 消息 远程控制 ESP32 LED

一、使用 Docker 快速启动 EMQX

1. 基础启动命令

最基础的 EMQX 容器启动方式如下：

bash 复制代码

docker run -itd \
  --name emqx \
  -p 1883:1883 \
  -p 8083:8083 \
  -p 8084:8084 \
  -p 8883:8883 \
  -p 18083:18083 \
  emqx/emqx

容器启动成功后会返回类似 ID：

text 复制代码

185326ea778710a12c77ad3b3e24800ce7591c30f4feb0196742bfd70f655d14

这样：

宿主机：1884
容器内部：1883（MQTT 默认端口）

二、访问 EMQX 控制台

浏览器访问（HTTPS）：

复制代码

https://服务器IP:18083

默认账号密码：

text 复制代码

用户名：admin
密码：public

控制台界面如下：

三、MicroPython MQTT 客户端实现

ESP32 使用 MicroPython ，MQTT 客户端代码基于 simple.py 实现。

1. MQTT 客户端库（simple.py）

文件名：simple.py

python 复制代码

import usocket as socket
import ustruct as struct
from ubinascii import hexlify


class MQTTException(Exception):
    pass


class MQTTClient:
    def __init__(
        self,
        client_id,
        server,
        port=0,
        user=None,
        password=None,
        keepalive=0,
        ssl=None,
    ):
        if port == 0:
            port = 8883 if ssl else 1883
        self.client_id = client_id
        self.sock = None
        self.server = server
        self.port = port
        self.ssl = ssl
        self.pid = 0
        self.cb = None
        self.user = user
        self.pswd = password
        self.keepalive = keepalive
        self.lw_topic = None
        self.lw_msg = None
        self.lw_qos = 0
        self.lw_retain = False

    def _send_str(self, s):
        self.sock.write(struct.pack("!H", len(s)))
        self.sock.write(s)

    def _recv_len(self):
        n = 0
        sh = 0
        while 1:
            b = self.sock.read(1)[0]
            n |= (b & 0x7F) << sh
            if not b & 0x80:
                return n
            sh += 7

    def set_callback(self, f):
        self.cb = f

    def set_last_will(self, topic, msg, retain=False, qos=0):
        self.lw_topic = topic
        self.lw_msg = msg
        self.lw_qos = qos
        self.lw_retain = retain

    def connect(self, clean_session=True):
        self.sock = socket.socket()
        addr = socket.getaddrinfo(self.server, self.port)[0][-1]
        self.sock.connect(addr)
        premsg = bytearray(b"\x10\0\0\0\0\0")
        msg = bytearray(b"\x04MQTT\x04\x02\0\0")

        sz = 10 + 2 + len(self.client_id)
        msg[6] = clean_session << 1
        if self.user:
            sz += 2 + len(self.user) + 2 + len(self.pswd)
            msg[6] |= 0xC0

        i = 1
        while sz > 0x7F:
            premsg[i] = (sz & 0x7F) | 0x80
            sz >>= 7
            i += 1
        premsg[i] = sz

        self.sock.write(premsg, i + 2)
        self.sock.write(msg)
        self._send_str(self.client_id)
        if self.user:
            self._send_str(self.user)
            self._send_str(self.pswd)

        resp = self.sock.read(4)
        if resp[3] != 0:
            raise MQTTException(resp[3])

    def subscribe(self, topic, qos=0):
        self.cb is not None
        pkt = bytearray(b"\x82\0\0\0")
        self.pid += 1
        struct.pack_into("!BH", pkt, 1, 2 + 2 + len(topic) + 1, self.pid)
        self.sock.write(pkt)
        self._send_str(topic)
        self.sock.write(qos.to_bytes(1, "little"))

    def check_msg(self):
        self.sock.setblocking(False)
        try:
            res = self.sock.read(1)
        except:
            return
        if res == b"\x30":
            self.sock.read(1)
            tlen = self.sock.read(2)
            tlen = (tlen[0] << 8) | tlen[1]
            topic = self.sock.read(tlen)
            msg = self.sock.read()
            self.cb(topic, msg)

四、ESP32 主程序（控制 LED）

文件名：main.py

python 复制代码

from simple import MQTTClient
from machine import Pin
import network

led = Pin(2, Pin.OUT)

SSID = "wifi名称"
PASSWORD = "wifi密码"

wlan = network.WLAN(network.STA_IF)
wlan.active(True)
if not wlan.isconnected():
    wlan.connect(SSID, PASSWORD)
    while not wlan.isconnected():
        pass

print("Network config:", wlan.ifconfig())

SERVER = "192.168.31.219"
PORT = 1884
CLIENT_ID = "my_micropython_client"

def sub(topic, msg):
    print(topic, msg)
    if topic == b"led002":
        if msg == b"on":
            led.value(0)
        elif msg == b"off":
            led.value(1)

client = MQTTClient(
    CLIENT_ID,
    SERVER,
    PORT,
    "test",
    "123456"
)

client.set_callback(sub)
client.connect()
client.subscribe(b"led002")

while True:
    client.check_msg()

五、测试效果

通过 EMQX 控制台或其他 MQTT 客户端：

Topic：led002
Payload：
- on → LED 亮
- off → LED 灭

设备成功订阅并响应：