WebHook Configuration

The WebHook feature in EMQX Edge enables the broker to automatically send HTTP POST requests to external services in response to specific MQTT events. This mechanism makes it easy to integrate EMQX Edge with external systems. For more information on the WebHook feature, see WebHook Integration Tutorial.

This page provides you with a sample configuration of the WebHook settings in the nanomq.conf configuration file.

Example Configuration

EMQX Edge supports defining multiple trigger rules through the configuration file. This section will demonstrate by defining two WebHook trigger rules as an example:

• Rule 1: When a message is sent to the "a/b/c" topic, trigger the WebHook.
• Rule 2: When a client initiates a connection request, trigger the WebHook.

The sample configuration is as follows:

webhook = {
  url = "http://127.0.0.1:80"        # URL where webhooks will send HTTP requests to
  headers.content-type = "application/json" # HTTP header specifying request content type
  body.encoding = "plain"            # Encoding format of the payload field in 
  cancel_timeout = 5000              # HTTP max timeout duration (ms)
  pool_size = 32                     # Connection process pool size
  events = [
    {
      event = "on_message_publish"   # Event type
      topic = "a/b/c"                # The specific topic that this event applies to
    }
    {
      event = "on_client_connack"    
    }
  ]
}

Configuration Items

• url: The URL where webhooks will send HTTP requests to when events occur. This should be the endpoint of a service that can handle these requests appropriately.
• headers.content-type: Content type of the HTTP request included in the headers. For example, "application/json" means HTTP request's body will be formatted as a JSON object.
• body.encoding: Encoding format of the payload field in the HTTP body. This field only appears in the on_message_publish and on_message_delivered events. The value can be plain, base64, or base62.
• pool_size: The connection process pool size. This determines the number of concurrent connections that webhooks can maintain with the endpoint specified in the url. Default: 32
• cancel_timeout: The HTTP connection waits cancel_timeout for reomte reply. 5 seconds by default. Exceeding this setting will result in Request canceled.
• events: An array of event objects. Each object specifies an event that can trigger a webhook:
  • event: Specify the type of the event that will trigger a webhook. The following events are supported:
    • on_client_connack
    • on_client_disconnected
    • on_message_publish
  • topic(Optional): For on_message_publish event, you can specify a particular topic. Webhooks are triggered only for messages published to this topic.

Upcoming Features

TLS

TLS-related configuration items will be supported in upcoming releases. Please stay tuned.

tls {
   	keyfile="/etc/certs/key.pem"
  	certfile="/etc/certs/cert.pem"
  	cacertfile="/etc/certs/cacert.pem"
}

Event

More events will be supported in upcoming releases. Please stay tuned.

• on_client_connect
• on_client_connected
• on_client_subscribe
• on_client_unsubscribe
• on_session_subscribed
• on_session_unsubscribed
• on_session_terminated
• on_message_delivered
• on_message_acked