Webhook

Setup

Prerequisites

A Netdata Cloud account
Access to the Space as an Admin
The Space needs to be on a paid plan
You need to have an app that allows you to receive webhooks following a predefined schema.

Netdata Configuration

Click on the Space settings cog (located above your profile icon)
Click on the Alerts & Notifications tab
Click on the + Add configuration button
Add the Webhook integration
A modal will be presented to you to enter the required details to enable the configuration:
- Notification settings
  - Configuration name (optional): A name for your configuration in order to easily refer to it
  - Rooms: A list of Rooms for which you want to be notified
  - Notifications: The notifications which you want to be notified
- Integration configuration
  - Webhook URL: The url of the service that Netdata will send notifications to. In order to keep the communication secured, Netdata only accepts HTTPS urls.
  - Extra headers: Optional key-value pairs that you can set to be included in the HTTP requests sent to the webhook URL.
  - Authentication Mechanism, Netdata webhook integration supports 3 different authentication mechanisms.
    - Mutual TLS (recommended): Default authentication mechanism used if no other method is selected
    - Basic: The client sends a request with an Authorization header that includes a base64-encoded string in the format username:password.
    - Bearer: The client sends a request with an Authorization header that includes a bearer token.

Webhook service

A webhook service allows your application to receive real-time alerts from Netdata by sending HTTP requests to a specified URL.

In this section, we’ll go over the steps to set up a generic webhook service, including adding headers, and implementing different types of authorization mechanisms.

Netdata webhook integration

Netdata webhook integration service will send alert and reachability notifications to the destination service as soon as they are detected.

For alert notifications, the content sent to the destination service contains a JSON object with the following properties:

field	type	description
message	string	A summary message of the alert.
alert	string	The alert the notification is related to.
info	string	Additional info related with the alert.
chart	string	The chart associated with the alert.
context	string	The chart context.
space	string	The space where the node that raised the alert is assigned.
Rooms	object[object(string,string)]	Object with list of Rooms names and urls where the node belongs to.
family	string	Context family.
class	string	Classification of the alert, e.g. `Error`.
severity	string	Alert severity, can be one of `warning`, `critical` or `clear`.
date	string	Date of the alert in ISO8601 format.
duration	string	Duration the alert has been raised.
additional_active_critical_alerts	integer	Number of additional critical alerts currently existing on the same node.
additional_active_warning_alerts	integer	Number of additional warning alerts currently existing on the same node.
alert_url	string	Netdata Cloud URL for this alert.

For reachability notifications, the JSON object will contain the following properties:

field	type	description
message	string	A summary message of the reachability alert.
url	string	Netdata Cloud URL for the host experiencing the reachability alert.
host	string	The hostname experiencing the reachability alert.
severity	string	Severity for this notification. If host is reachable, severity will be `info`, if host is unreachable, it will be `critical`.
status	object	An object with the status information.
status.reachable	boolean	`true` if host is reachable, `false` otherwise
status.text	string	Can be `reachable` or `unreachable`

Extra headers

When setting up a webhook service, the user can specify a set of headers to be included in the HTTP requests sent to the webhook URL.

By default, the following headers will be sent in the HTTP request

Header	Value
Content-Type	application/json

Authentication mechanisms

Netdata webhook integration supports 3 different authentication mechanisms:

Mutual TLS authentication (recommended)

In mutual Transport Layer Security (mTLS) authentication, the client and the server authenticate each other using X.509 certificates. This ensures that the client is connecting to the intended server, and that the server is only accepting connections from authorized clients.

This is the default authentication mechanism used if no other method is selected.

To take advantage of mutual TLS, you can configure your server to verify Netdata’s client certificate. In order to achieve this, the Netdata client sending the notification supports mutual TLS (mTLS) to identify itself with a client certificate that your server can validate.

The steps to perform this validation are as follows:

Store Netdata CA certificate on a file in your disk. The content of this file should be:

Netdata CA certificate

Enable client certificate validation on the web server that is doing the TLS termination. Below there are examples on how to perform this configuration in NGINX and Apache.

NGINX

server {
    listen 443 ssl default_server;

    # ... existing SSL configuration for server authentication ...
    ssl_verify_client on;
    ssl_client_certificate /path/to/Netdata_CA.pem;

    location / {
        if ($ssl_client_s_dn !~ "CN=app.netdata.cloud") {
            return 403;
        }
        # ... existing location configuration ...
    }
}

Apache

Listen 443
<VirtualHost *:443>
    # ... existing SSL configuration for server authentication ...
    SSLVerifyClient require
    SSLCACertificateFile "/path/to/Netdata_CA.pem"
</VirtualHost>
<Directory /var/www/>
    Require expr "%{SSL_CLIENT_S_DN_CN} == 'app.netdata.cloud'"
    # ... existing directory configuration ...
</Directory>

Basic authentication

In basic authorization, the client sends a request with an Authorization header that includes a base64-encoded string in the format username:password. The server then uses this information to authenticate the client. If this authentication method is selected, the user can set the user and password that will be used when connecting to the destination service.

Bearer token authentication

In bearer token authentication, the client sends a request with an Authorization header that includes a bearer token. The server then uses this token to authenticate the client. Bearer tokens are typically generated by an authentication service, and are passed to the client after a successful authentication. If this method is selected, the user can set the token to be used for connecting to the destination service.

Challenge secret

To validate that you have ownership of the web application that will receive the webhook events, Netdata is using a challenge response check mechanism.

This mechanism works as follows:

The challenge secret parameter that you provide is a shared secret between only you and Netdata.
On your request for creating a new Webhook integration, Netdata will make a GET request to the URL of the webhook, adding a query parameter crc_token, consisting of a random string.
You will receive this request on your application and it must construct an encrypted response, consisting of a base64-encoded HMAC SHA-256 hash created from the crc_token and the shared secret. The response will be in the format:
```
{
"response_token": "sha256=9GKoHJYmcHIkhD+C182QWN79YBd+D+Vkj4snmZrfNi4="
}
```
Netdata will compare your application’s response with the hash that it will generate using the challenge secret, and if they are the same, the integration creation will succeed.

Netdata does this validation every time you update your integration configuration.

Response requirements:
- A base64 encoded HMAC SHA-256 hash created from the crc_token and the shared secret.
- Valid response_token and JSON format.
- Latency less than 5 seconds.
- 200 HTTP response code.

Example response token generation in Python:

Here you can see how to define a handler for a Flask application in python 3:

import base64
import hashlib
import hmac
import json

key ='YOUR_CHALLENGE_SECRET'

@app.route('/webhooks/netdata')
def webhook_challenge():
token = request.args.get('crc_token').encode('ascii')

# creates HMAC SHA-256 hash from incomming token and your consumer secret
sha256_hash_digest = hmac.new(key.encode(),
                                msg=token,
                                digestmod=hashlib.sha256).digest()

# construct response data with base64 encoded hash
response = {
    'response_token': 'sha256=' + base64.b64encode(sha256_hash_digest).decode('ascii')
}

# returns properly formatted json response
return json.dumps(response)

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