MQTT

The MQTT input connects to an MQTT broker, subscribes to one or more topics, and receives real-time messages. As a channel-based input it follows the engine's cancellation-safety contract: dropping a pending read never loses an already-decoded message (see Input Delivery Semantics).

Configuration

Field	Type	Required	Default	Description
type	string	yes	—	Constant value "mqtt"
host	string	yes	—	MQTT broker address
port	integer	yes	—	MQTT broker port
client_id	string	yes	—	Unique client identifier
topics	array<string>	yes	—	List of topics to subscribe to (wildcards supported)
username	string	no	—	Authentication username
password	string	no	—	Authentication password
qos	integer	no	—	QoS level (0, 1, 2)
clean_session	boolean	no	—	Whether to use a clean session
keep_alive	integer	no	—	Keep-alive interval (seconds)

TLS

Set the tls block to connect over TLS (MQTT over port 8883):

yaml

input:
  type: "mqtt"
  host: "localhost"
  port: 8883
  client_id: "tls-client"
  topics: ["demo"]
  tls:
    enabled: true
    ca: "/etc/arkflow/certs/ca.pem"

enabled defaults to true when the block is present (set enabled: false to keep the block as documentation); ca verifies the broker certificate; client_cert/client_key enable mTLS and must be configured together. ca is optional with mTLS: without it the broker is verified against the platform trust store (e.g. public brokers with system-issued certificates). client_cert without client_key (or vice versa) is a configuration error. Omitting the tls block keeps plain TCP. The client_id must be unique per connection.

Examples

yaml

input:
  type: "mqtt"
  host: "localhost"
  port: 1883
  client_id: "my_client"
  username: "user"
  password: "pass"
  topics:
    - "sensors/temperature"
    - "sensors/humidity"
  qos: 1
  clean_session: true
  keep_alive: 60