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MQTT plugin

The MQTT plugin is a Source-and-sink plugin that connects to an MQTT 5 broker. Each Tenon channel owns one client; the Source and Sink sides share that client. Build it from the same Tenon source checkout as the Runner:

cargo tenon bundle --locked \
  --manifest-path plugin/bifromq-tenon-mqtt-plugin/Cargo.toml > mqtt-bundle.json

Choose the target matching the Runner and install the local bundle with POST /plugins. The package identity is org.apache.bifromq.tenon.mqtt@0.1.0 for this plugin build.

Configuration​

{
  "endpoint": "mqtt://127.0.0.1:1883",
  "clientIdPrefix": "tenon-dev-",
  "eventLoopThreads": 1,
  "session": {"cleanStart": false, "expiryIntervalSeconds": 86400},
  "source": {"subscriptions": [{"filter": "devices/+/events", "qos": 1}]},
  "sink": {"defaultQos": 1, "defaultRetain": false}
}

endpoint accepts mqtt:// and mqtts://. Set a unique clientIdPrefix. source.subscriptions can be omitted or empty when only publishing. The configured session.cleanStart value is used on every connection, including the first connection; Tenon does not override it for an initial startup. Verify broker session behavior with the broker and client IDs in your deployment.

Payloads​

The Source payload contains message.topic, binary message.body, optional QoS and retain values, the DUP flag, and the receive timestamp. The Sink payload contains a message with topic, body, and optional QoS/retain values. The exact proto definitions are in the source repository.

For a Source-to-Sink pass-through, bind both interfaces and use the exact Sink contract:

local builder = registry:getBuilder("org.apache.bifromq.tenon.mqtt@0.1.0")

function main(event)
  if event.type == "source" then
    local message = builder:getMessageBuilder()
    message:setTopic(event.payload.message.topic)
    message:setBody(event.payload.message.body)
    emit(builder:build())
  end
end

Use : for all Builder calls. QoS and reconnect behavior can produce duplicates; downstream consumers should tolerate them. Check actual subscriber output separately from Pipeline running state.

Build and install​

The complete schema and package details are maintained in the Tenon source tree. Install through the normal Runner API; do not edit the Runner's private state directory.