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I am trying to apply HAProxy acl to choose mqtt broker backend is not working. I have tried following HAProxy configurations.

Environment:

HAProxy version: 1.8.19 MQTT Broker: EMQ X Broker version 3.0

Sample Config 1

listen mqtt
    bind *:80
    mode tcp
    maxconn 50000

    acl mqtt-request hdr_beg(host) -i mqtt.mydoamin.com
    use_backend backend_mqtt if mqtt-request

  backend backend_mqtt
    mode tcp
    server smg1 192.168.0.100:1883 check

Sample Config 2

listen mqtt
    bind *:80
    mode tcp
    maxconn 50000

    acl mqtt_request req.payload(4,15) -m sub mqtt.mydoamin.com
    tcp-request content accept if mqtt_request
    use_backend backend_mqtt  if mqtt_request

  backend backend_mqtt
    mode tcp
    server smg1 192.168.0.100:1883 check

Sample Config 3

listen mqtt
    bind *:80
    mode tcp
    maxconn 50000

    acl host_mqtt hdr(host) -i mqtt.mydoamin.com
    use_backend backend_mqtt if host_mqtt

  backend backend_mqtt
    mode tcp
    server smg1 192.168.0.100:1883 check

Sample Config 4

listen mqtt
    bind *:80
    mode tcp
    maxconn 50000

    use_backend backend_mqtt if { hdr_end(host) -i mqtt.mydoamin.com }

  backend backend_mqtt
    mode tcp
    server smg1 192.168.0.100:1883 check

None of above configurations is working to match the host (mqtt.mydoamin.com).

Shaukat Mahmood Ahmad
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1 Answers1

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If you're using mode tcp in haproxy then you can't match HTTP headers with hdr() etc.

Is HTTP being spoken on this connection? Then use mode http. If not (you're actually using MQTT protocol on port 80) then you cannot match the hostname, as that is not communicated over the connection. You can only use different MQTT brokers on one system by using differing IP addresses and/or different port numbers.

wurtel
  • 3,806
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  • Thanks @wurtel, I was thinking if `req.payload(4,15) -m sub mqtt.mydoamin.com` with tcp transport will work. I have studied the MQTT protocol specs and have to found any of such header / payload contents that can help identify the host name of the request. – Shaukat Mahmood Ahmad Apr 13 '19 at 21:56