mqtt-proxy

Description

The mqtt-proxy Plugin is used for dynamic load balancing with client_id of MQTT. It only works in stream model.

This Plugin supports both the protocols 3.1.* and 5.0.

Attributes

Name	Type	Required	Description
protocol_name	string	True	Name of the protocol. Generally MQTT.
protocol_level	integer	True	Level of the protocol. It should be 4 for MQTT 3.1.* and 5 for MQTT 5.0.
upstream	object	Deprecated	Use separate Upstream in the Route instead.
upstream.host	string	True	IP or host of the upstream to forward the current request to.
upstream.ip	string	Deprecated	Use host instead. IP address of the upstream to forward the current request to.
upstream.port	number	True	Port of the upstream to forward the current request to.

Enabling the Plugin

To enable the Plugin, you need to first enable the stream_proxy configuration in your configuration file (conf/config.yaml). The below configuration represents listening on the 9100 TCP port:

conf/config.yaml

    ...
    router:
        http: 'radixtree_uri'
        ssl: 'radixtree_sni'
    stream_proxy:                 # TCP/UDP proxy
      only: false                 # needed if HTTP and Stream Proxy should be enabled
      tcp:                        # TCP proxy port list
        - 9100
    dns_resolver:
    ...

You can now send the MQTT request to port 9100.

You can now create a stream Route and enable the mqtt-proxy Plugin:

curl http://127.0.0.1:9080/apisix/admin/stream_routes/1 -H 'X-API-KEY: edd1c9f034335f136f87ad84b625c8f1' -X PUT -d '
{
    "plugins": {
        "mqtt-proxy": {
            "protocol_name": "MQTT",
            "protocol_level": 4
        }
    },
    "upstream": {
        "type": "roundrobin",
        "nodes": [{
            "host": "127.0.0.1",
            "port": 1980,
            "weight": 1
        }]
    }
}'

note

If you are using Docker in macOS, then host.docker.internal is the right parameter for the host attribute.

This Plugin exposes a variable mqtt_client_id which can be used for load balancing as shown below:

curl http://127.0.0.1:9080/apisix/admin/stream_routes/1 -H 'X-API-KEY: edd1c9f034335f136f87ad84b625c8f1' -X PUT -d '
{
    "plugins": {
        "mqtt-proxy": {
            "protocol_name": "MQTT",
            "protocol_level": 4
        }
    },
    "upstream": {
        "type": "chash",
        "key": "mqtt_client_id",
        "nodes": [
        {
            "host": "127.0.0.1",
            "port": 1995,
            "weight": 1
        },
        {
            "host": "127.0.0.2",
            "port": 1995,
            "weight": 1
        }
        ]
    }
}'

MQTT connections with different client ID will be forwarded to different nodes based on the consistent hash algorithm. If client ID is missing, client IP is used instead for load balancing.

Enabling mTLS with mqtt-proxy plugin

Stream proxies use TCP connections and can accept TLS. Follow the guide about how to accept tls over tcp connections to open a stream proxy with enabled TLS.

The mqtt-proxy plugin is enabled through TCP communications on the specified port for the stream proxy, and will also require clients to authenticate via TLS if tls is set to true.

Configure ssl providing the CA certificate and the server certificate, together with a list of SNIs. Steps to protect stream_routes with ssl are equivalent to the ones to protect Routes

Create a stream_route using mqtt-proxy plugin and mTLS

Here is an example of how create a stream_route which is using the mqtt-proxy plugin, providing the CA certificate, the client certificate and the client key (for self-signed certificates which are not trusted by your host, use the -k flag):

curl 127.0.0.1:9180/apisix/admin/stream_routes/1 -H 'X-API-KEY: edd1c9f034335f136f87ad84b625c8f1' -X PUT -d '
{
    "plugins": {
        "mqtt-proxy": {
            "protocol_name": "MQTT",
            "protocol_level": 4
        }
    },
    "sni": "${your_sni_name}",
    "upstream": {
        "nodes": {
            "127.0.0.1:1980": 1
        },
        "type": "roundrobin"
    }
}'

The sni name must math one or more of the SNIs provided to the SSL object that you created with the CA and server certificates.

Disable Plugin

To disable the mqtt-proxy Plugin you can remove the corresponding configuration as shown below:

curl http://127.0.0.1:9080/apisix/admin/stream_routes/1 -H 'X-API-KEY: edd1c9f034335f136f87ad84b625c8f1' -X DELETE