Webhook

Overview

Send notifications to a Webhook in a specific format.

About Webhook Notifier

The Webhook notifier will perform an HTTP POST request to the specified endpoint everytime a change in the flags is detected.

The format of the call is specified in the format section and you can sign the body to trust the data you are receiving.

Format

If you have configured a webhook, a POST request will be sent to the EndpointURL with a body in this format:

{
  "meta": {
    "hostname": "server01"
    // ...
  },
  "flags": {
    "deleted": {},
    // map of your deleted flags
    "added": {},
    // map of your added flags
    "updated": {
      "flag-name": {
        // an object that contains old and new value
        "old_value": {},
        "new_value": {}
      }
    }
  }
}

Example

{
  "meta": {
    "hostname": "server01"
  },
  "flags": {
    "deleted": {
      "test-flag": {
        "rule": "key eq \"random-key\"",
        "percentage": 100,
        "true": true,
        "false": false,
        "default": false
      }
    },
    "added": {
      "test-flag3": {
        "percentage": 5,
        "true": "test",
        "false": "false",
        "default": "default"
      }
    },
    "updated": {
      "test-flag2": {
        "old_value": {
          "rule": "key eq \"not-a-key\"",
          "percentage": 100,
          "true": true,
          "false": false,
          "default": false
        },
        "new_value": {
          "disable": true,
          "rule": "key eq \"not-a-key\"",
          "percentage": 100,
          "true": true,
          "false": false,
          "default": false
        }
      }
    }
  }
}

Signature

This header X-Hub-Signature-256 is sent if the webhook is configured with a secret. This is the HMAC hex digest of the request body, and is generated using the SHA-256 hash function and the secret as the HMAC key.

caution

The recommendation is to always use the Secret and on your API/webook always verify the signature key to be sure that you don't get into a man-in-the-middle attack.

Configure the relay proxy

To configure your relay proxy to use the Webhook notifier, you need to add the following configuration to your relay proxy configuration file:

goff-proxy.yaml

# ...
notifier:
  - kind: webhook
    endpointUrl: "https://example.com/hook"
# ...

Field name	Mandatory	Type	Default	Description
kind		string	none	Value should be webhook. This field is mandatory and describes which retriever you are using.
endpointUrl		string	none	The complete URL of your API (we will send a POST request to this URL, see format
secret		string	none	Secret used to sign your request body and fill the X-Hub-Signature-256 header. See signature section for more details.
meta		map[string]string	none	Add all the information you want to see in your request.
headers		map[string][]string	none	Add all the headers you want to add while calling the endpoint

Configure the GO Module

To configure your GO module to use the Webhook notifier, you need to add the following configuration to your ffclient.Config{} object:

example.go

err := ffclient.Init(ffclient.Config{
    // ...
    Notifiers: []notifier.Notifier{
        &webhooknotifier.Notifier{
            EndpointURL: "https://example.com/hook",
            Secret:     "Secret",
            Meta: map[string]string{
                "app.name": "my app",
            },
            Headers: map[string][]string{
                "Authorization": {"Bearer auth_token"},
            },
        },
    // ...
    },
})
defer ffclient.Close()

Field	Mandatory	Description
EndpointURL		The complete URL of your API (we will send a POST request to this URL, see format)
Secret		A secret key you can share with your webhook. We will use this key to sign the request (see signature section for more details).
Meta		A list of key value that will be added in your request, this is super useful if you want to add information on the current running instance of your app. By default the hostname is always added in the meta information.
Headers		The list of Headers to send to the endpoint.