客户端连接到 VerneMQ 集群

Question

我们设置了一个 VerneMQ 3 节点集群 (https://vernemq.com/docs/clustering/)。

问题是我没有找到任何关于如何将客户端连接到整个集群的示例。

例如对于单个 VerneMQ 实例，客户端连接 (in python) 是：

client.connect("xxx.xxx.xxx.xxx", 1883, 60)

其中"xxx.xxx.xxx.xxx"为单实例地址
如果是集群，有没有办法指定整个集群的地址，而不是指向单个节点？

Answer 1

没有"specific address of the whole cluster"这样的东西。（对于 VerneMQ 和任何其他集群服务器软件）。

如果你需要单点联系，你需要在集群前面有一个负载均衡器。然后，您可以使用不同的负载平衡策略。

例如，VerneMQ 与 HAProxy 配合良好，并支持代理协议。

希望对您有所帮助。

Answer 2

我的客户端使用 Paho MQTT client library, I ended up in using the following 客户端 class 的扩展编写：

import random
from paho.mqtt.client import *


class ClusterClient(Client):
    """A subclass of paho.mqtt.Client that supports connecting to a cluster of
       mqtt brokers. connect() and connect_async() additionally accept a list
       of hostnames or host/port tuples:

           connect("host1")

           connect(["host1", "host2", "host3"]) # use default port 1883

           connect(["host1", ("host2", 8883), ("host3", 8883)])

       Hosts to connect to are chosen randomly. If a host disappears the client
       automatically connects to another host from the list.
    """

    def __init__(self, client_id="", clean_session=True, userdata=None,
            protocol=MQTTv311, transport="tcp"):
        super().__init__(client_id, clean_session, userdata, protocol, transport)
        self._hosts = []

    def connect_async(self, host, port=1883, keepalive=60, bind_address=""):
        if isinstance(host, (list, tuple)):
            self._hosts = [(t, 1883) if isinstance(t, str) else t for t in host]
        else:
            self._hosts = [(host, port)]

        for host, port in self._hosts:
            if host is None or len(host) == 0:
                raise ValueError('Invalid host.')
            if port <= 0:
                raise ValueError('Invalid port number.')

        host, port = random.choice(self._hosts)

        super().connect_async(host, port, keepalive, bind_address)

    def reconnect(self):
        hosts = self._hosts[:]
        random.shuffle(hosts)
        while True:
            self._host, self._port = hosts.pop(0)
            try:
                return super().reconnect()
            except socket.error:
                if not hosts:
                    raise

客户端连接到 VerneMQ 集群

Client connection to VerneMQ cluster

python

cluster-computing

paho

mqtt-vernemq