Prerequisites

• Dowlnoad the required installation packgaes and upload them to your servers.
• Prepare three CentOS 7 virtual machines or physical servers.

Configuring the EMQX Cluster

On each of the three nodes, navigate to the etc directory inside the extracted EMQX folder and edit emqx.conf:

cluster.discovery = static
cluster.static.seeds = emqx1@192.168.0.210,emqx2@192.168.0.211,emqx3@192.168.0.212
node.name = emqx1@192.168.0.210
node.dist_listen_min = 6369
node.dist_listen_max = 7369

Replace emqx1, emqx2, and emqx3 with unique node names per host, using their respective IP addresses.

Starting EMQX

Use the following commands to manage the EMQX service:

./bin/emqx start   # Start
./bin/emqx stop    # Stop

Verify cluster formation by accessing the dashboard at http://<server-ip>:18083 on any node.

Installing and Configuring HAProxy

Compile and install HAProxy from source:

cd haproxy-1.8.10
make TARGET=linux2628 ARCH=x86_64 PREFIX=/home/soft/haproxy
make install PREFIX=/home/soft/haproxy

Create a configuraton file at /home/soft/haproxy/sbin/haproxy.cfg:

global
    log 127.0.0.1 local0
    log 127.0.0.1 local1 notice
    daemon
    nbproc 2
    maxconn 51200
    pidfile /home/soft/haproxy/sbin/haproxy.pid

defaults
    log global
    mode tcp
    option tcplog
    option dontlognull
    retries 3
    timeout connect 5000ms
    timeout client 30000ms
    timeout server 60000ms
    balance roundrobin

listen stats
    bind *:9080
    mode http
    stats enable
    stats uri /stats
    stats realm "HAProxy Manager"
    stats admin if TRUE

listen mqtt_backend
    bind *:1890
    mode tcp
    timeout client 3h
    timeout server 3h
    option clitcpka
    balance leastconn
    server emqx1 192.168.0.210:1883 check inter 10s fall 2 rise 5
    server emqx2 192.168.0.211:1883 check inter 10s fall 2 rise 5
    server emqx3 192.168.0.212:1883 check inter 10s fall 2 rise 5

Start HAProxy with:

./haproxy -f haproxy.cfg

Clients should now connect to the MQTT cluster via 192.168.0.210:1890 (or any HAProxy node’s IP). Test connectivity and failover behavior using an MQTT client such as MQTT.fx.