NATS trigger

NOTE: NATS trigger is in tech-preview.

Reads messages from NATS topics. Function replicas are subscribed to a worker group (queue), and messages are load-balanced across replicas. To join a specific worker group, specify a queue-name attribute in the trigger configuration.

The queue name may be a Go template, which may include any of the following fields:

Name	Type	Description
Id	string	The trigger id
Namespace	string	The function deployment namespace
Name	string	The deployed function name
Labels	map	Labels specified in the function metadata
Annotations	map	Annotations specified in the function metadata

Attributes

Path	Type	Description
topic	string	The topic on which to listen.
queueName	string	The name of a shared worker queue to join; (default: an auto-generated name per trigger).
reply	bool	When set to true, publish the handler response body to the incoming message reply subject (msg.Reply) if present. See Reply encoding for details.

Reply encoding

When reply is enabled, the trigger publishes the handler’s return value to the NATS reply subject using the following rules:

Response body type	Behavior
[]byte	Published as-is.
string	Converted to bytes and published.
Any other type	JSON-serialized before publishing.
nil	An empty message (no payload) is published.
(no reply subject)	If the incoming NATS message has no reply subject (i.e. it was sent with Publish rather than Request), no reply is published regardless of this setting.

Example

triggers:
  myNatsTopic:
    kind: "nats"
    url: "nats://10.0.0.3:4222"
    attributes:
      "topic": "my.topic"
      "queueName": "{{ .Namespace }}.{{ .Name }}.{{ .Id }}"
      "reply": true