Merge pull request #4263 from netbox-community/4237-custom-webhooks

Closes #4237: Enable custom templating for webhook request content

docs/additional-features/webhooks.md

@@ -1,61 +1,73 @@
 # Webhooks
 
-A webhook defines an HTTP request that is sent to an external application when certain types of objects are created, updated, and/or deleted in NetBox. When a webhook is triggered, a POST request is sent to its configured URL. This request will include a full representation of the object being modified for consumption by the receiver. Webhooks are configured via the admin UI under Extras > Webhooks.
+A webhook is a mechanism for conveying to some external system a change that took place in NetBox. For example, you may want to notify a monitoring system whenever a device status is changed in NetBox. This can be done by creating a webhook for the device model in NetBox. When NetBox detects a change to a device, an HTTP request containing the details of the change and who made it be sent to the specified receiver. Webhooks are configured in the admin UI under Extras > Webhooks.
 
-An optional secret key can be configured for each webhook. This will append a `X-Hook-Signature` header to the request, consisting of a HMAC (SHA-512) hex digest of the request body using the secret as the key. This digest can be used by the receiver to authenticate the request's content.
+## Configuration
 
-## Requests
+* **Name** - A unique name for the webhook. The name is not included with outbound messages.
+* **Object type(s)** - The type or types of NetBox object that will trigger the webhook.
+* **Enabled** - If unchecked, the webhook will be inactive.
+* **Events** - A webhook may trigger on any combination of create, update, and delete events. At least one event type must be selected.
+* **HTTP method** - The type of HTTP request to send. Options include GET, POST, PUT, PATCH, and DELETE.
+* **URL** - The fuly-qualified URL of the request to be sent. This may specify a destination port number if needed.
+* **HTTP content type** - The value of the request's `Content-Type` header. (Defaults to `application/json`)
+* **Additional headers** - Any additional headers to include with the request (optional). Add one header per line in the format `Name: Value`. Jinja2 templating is supported for this field (see below).
+* **Body template** - The content of the request being sent (optional). Jinja2 templating is supported for this field (see below). If blank, NetBox will populate the request body with a raw dump of the webhook context. (If the HTTP cotent type is set to `application/json`, this will be formatted as a JSON object.)
+* **Secret** - A secret string used to prove authenticity of the request (optional). This will append a `X-Hook-Signature` header to the request, consisting of a HMAC (SHA-512) hex digest of the request body using the secret as the key.
+* **SSL verification** - Uncheck this option to disable validation of the receiver's SSL certificate. (Disable with caution!)
+* **CA file path** - The file path to a particular certificate authority (CA) file to use when validating the receiver's SSL certificate (optional).
 
-The webhook POST request is structured as so (assuming `application/json` as the Content-Type):
+## Jinja2 Template Support
+
+[Jinja2 templating](https://jinja.palletsprojects.com/) is supported for the `additional_headers` and `body_template` fields. This enables the user to convey change data in the request headers as well as to craft a customized request body. Request content can be crafted to enable the direct interaction with external systems by ensuring the outgoing message is in a format the receiver expects and understands.
+
+For example, you might create a NetBox webhook to [trigger a Slack message](https://api.slack.com/messaging/webhooks) any time an IP address is created. You can accomplish this using the following configuration:
+
+* Object type: IPAM > IP address
+* HTTP method: POST
+* URL: <Slack incoming webhook URL>
+* HTTP content type: `application/json`
+* Body template: `{"text": "IP address {{ data['address'] }} was created by {{ username }}!"}`
+
+### Available Context
+
+The following data is available as context for Jinja2 templates:
+
+* `event` - The type of event which triggered the webhook: created, updated, or deleted.
+* `model` - The NetBox model which triggered the change.
+* `timestamp` - The time at which the event occurred (in [ISO 8601](https://en.wikipedia.org/wiki/ISO_8601) format).
+* `username` - The name of the user account associated with the change.
+* `request_id` - The unique request ID. This may be used to correlate multiple changes associated with a single request.
+* `data` - A serialized representation of the object _after_ the change was made. This is typically equivalent to the model's representation in NetBox's REST API.
+
+### Default Request Body
+
+If no body template is specified, the request body will be populated with a JSON object containing the context data. For example, a newly created site might appear as follows:
 
 ```no-highlight
 {
     "event": "created",
-    "timestamp": "2019-10-12 12:51:29.746944",
+    "timestamp": "2020-02-25 15:10:26.010582+00:00",
-    "username": "admin",
     "model": "site",
-    "request_id": "43d8e212-94c7-4f67-b544-0dcde4fc0f43",
+    "username": "jstretch",
+    "request_id": "fdbca812-3142-4783-b364-2e2bd5c16c6a",
     "data": {
+        "id": 19,
+        "name": "Site 1",
+        "slug": "site-1",
+        "status": 
+            "value": "active",
+            "label": "Active",
+            "id": 1
+        },
+        "region": null,
         ...
     }
 }
 ```
 
-`data` is the serialized representation of the model instance(s) from the event. The same serializers from the NetBox API are used. So an example of the payload for a Site delete event would be:
+## Webhook Processing
 
-```no-highlight
+When a change is detected, any resulting webhooks are placed into a Redis queue for processing. This allows the user's request to complete without needing to wait for the outgoing webhook(s) to be processed. The webhooks are then extracted from the queue by the `rqworker` process and HTTP requests are sent to their respective destinations. The current webhook queue and any failed webhooks can be inspected in the admin UI under Django RQ > Queues.
-{
-    "event": "deleted",
-    "timestamp": "2019-10-12 12:55:44.030750",
-    "username": "johnsmith",
-    "model": "site",
-    "request_id": "e9bb83b2-ebe4-4346-b13f-07144b1a00b4",
-    "data": {
-        "asn": None,
-        "comments": "",
-        "contact_email": "",
-        "contact_name": "",
-        "contact_phone": "",
-        "count_circuits": 0,
-        "count_devices": 0,
-        "count_prefixes": 0,
-        "count_racks": 0,
-        "count_vlans": 0,
-        "custom_fields": {},
-        "facility": "",
-        "id": 54,
-        "name": "test",
-        "physical_address": "",
-        "region": None,
-        "shipping_address": "",
-        "slug": "test",
-        "tenant": None
-    }
-}
-```
 
-A request is considered successful if the response status code is any one of a list of "good" statuses defined in the [requests library](https://github.com/requests/requests/blob/205755834d34a8a6ecf2b0b5b2e9c3e6a7f4e4b6/requests/models.py#L688), otherwise the request is marked as having failed. The user may manually retry a failed request.
+A request is considered successful if the response has a 2XX status code; otherwise, the request is marked as having failed. Failed requests may be retried manually via the admin UI.
-
-## Backend Status
-
-Django-rq includes a status page in the admin site which can be used to view the result of processed webhooks and manually retry any failed webhooks. Access it from http://netbox.local/admin/webhook-backend-status/.

docs/release-notes/version-2.7.md

@@ -4,6 +4,7 @@
 
 * [#3145](https://github.com/netbox-community/netbox/issues/3145) - Add a "decommissioning" cable status
 * [#4173](https://github.com/netbox-community/netbox/issues/4173) - Return graceful error message when webhook queuing fails
+* [#4237](https://github.com/netbox-community/netbox/issues/4237) - Support Jinja2 templating for webhook payload and headers
 
 ## Bug Fixes
 

netbox/extras/admin.py

@@ -26,7 +26,7 @@ class WebhookForm(forms.ModelForm):
 
     class Meta:
         model = Webhook
-        exclude = []
+        exclude = ()
 
     def __init__(self, *args, **kwargs):
         super().__init__(*args, **kwargs)
@@ -38,13 +38,35 @@ class WebhookForm(forms.ModelForm):
 @admin.register(Webhook, site=admin_site)
 class WebhookAdmin(admin.ModelAdmin):
     list_display = [
-        'name', 'models', 'payload_url', 'http_content_type', 'enabled', 'type_create', 'type_update',
+        'name', 'models', 'payload_url', 'http_content_type', 'enabled', 'type_create', 'type_update', 'type_delete',
-        'type_delete', 'ssl_verification',
+        'ssl_verification',
     ]
     list_filter = [
         'enabled', 'type_create', 'type_update', 'type_delete', 'obj_type',
     ]
     form = WebhookForm
+    fieldsets = (
+        (None, {
+            'fields': (
+                'name', 'obj_type', 'enabled',
+            )
+        }),
+        ('Events', {
+            'fields': (
+                'type_create', 'type_update', 'type_delete',
+            )
+        }),
+        ('HTTP Request', {
+            'fields': (
+                'payload_url', 'http_method', 'http_content_type', 'additional_headers', 'body_template', 'secret',
+            )
+        }),
+        ('SSL', {
+            'fields': (
+                'ssl_verification', 'ca_file_path',
+            )
+        })
+    )
 
     def models(self, obj):
         return ', '.join([ct.name for ct in obj.obj_type.all()])

netbox/extras/choices.py

@@ -124,17 +124,18 @@ class TemplateLanguageChoices(ChoiceSet):
 # Webhooks
 #
 
-class WebhookContentTypeChoices(ChoiceSet):
+class WebhookHttpMethodChoices(ChoiceSet):
 
-    CONTENTTYPE_JSON = 'application/json'
+    METHOD_GET = 'GET'
-    CONTENTTYPE_FORMDATA = 'application/x-www-form-urlencoded'
+    METHOD_POST = 'POST'
+    METHOD_PUT = 'PUT'
+    METHOD_PATCH = 'PATCH'
+    METHOD_DELETE = 'DELETE'
 
     CHOICES = (
-        (CONTENTTYPE_JSON, 'JSON'),
+        (METHOD_GET, 'GET'),
-        (CONTENTTYPE_FORMDATA, 'Form data'),
+        (METHOD_POST, 'POST'),
+        (METHOD_PUT, 'PUT'),
+        (METHOD_PATCH, 'PATCH'),
+        (METHOD_DELETE, 'DELETE'),
     )
-
-    LEGACY_MAP = {
-        CONTENTTYPE_JSON: 1,
-        CONTENTTYPE_FORMDATA: 2,
-    }

netbox/extras/constants.py

@@ -138,6 +138,8 @@ LOG_LEVEL_CODES = {
     LOG_FAILURE: 'failure',
 }
 
+HTTP_CONTENT_TYPE_JSON = 'application/json'
+
 # Models which support registered webhooks
 WEBHOOK_MODELS = Q(
     Q(app_label='circuits', model__in=[

netbox/extras/migrations/0038_webhook_template_support.py

@@ -0,0 +1,48 @@
+import json
+
+from django.db import migrations, models
+
+
+def json_to_text(apps, schema_editor):
+    """
+    Convert a JSON representation of HTTP headers to key-value pairs (one header per line)
+    """
+    Webhook = apps.get_model('extras', 'Webhook')
+    for webhook in Webhook.objects.exclude(additional_headers=''):
+        data = json.loads(webhook.additional_headers)
+        headers = ['{}: {}'.format(k, v) for k, v in data.items()]
+        Webhook.objects.filter(pk=webhook.pk).update(additional_headers='\n'.join(headers))
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('extras', '0037_configcontexts_clusters'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='webhook',
+            name='http_method',
+            field=models.CharField(default='POST', max_length=30),
+        ),
+        migrations.AddField(
+            model_name='webhook',
+            name='body_template',
+            field=models.TextField(blank=True),
+        ),
+        migrations.AlterField(
+            model_name='webhook',
+            name='additional_headers',
+            field=models.TextField(blank=True, default=''),
+            preserve_default=False,
+        ),
+        migrations.AlterField(
+            model_name='webhook',
+            name='http_content_type',
+            field=models.CharField(default='application/json', max_length=100),
+        ),
+        migrations.RunPython(
+            code=json_to_text
+        ),
+    ]

netbox/extras/models.py

@@ -1,3 +1,4 @@
+import json
 from collections import OrderedDict
 from datetime import date
 
@@ -12,6 +13,7 @@ from django.http import HttpResponse
 from django.template import Template, Context
 from django.urls import reverse
 from django.utils.text import slugify
+from rest_framework.utils.encoders import JSONEncoder
 from taggit.models import TagBase, GenericTaggedItemBase
 
 from utilities.fields import ColorField
@@ -52,7 +54,6 @@ class Webhook(models.Model):
     delete in NetBox. The request will contain a representation of the object, which the remote application can act on.
     Each Webhook can be limited to firing only on certain actions or certain object types.
     """
-
     obj_type = models.ManyToManyField(
         to=ContentType,
         related_name='webhooks',
@@ -81,17 +82,33 @@ class Webhook(models.Model):
         verbose_name='URL',
         help_text="A POST will be sent to this URL when the webhook is called."
     )
-    http_content_type = models.CharField(
+    enabled = models.BooleanField(
-        max_length=50,
+        default=True
-        choices=WebhookContentTypeChoices,
-        default=WebhookContentTypeChoices.CONTENTTYPE_JSON,
-        verbose_name='HTTP content type'
     )
-    additional_headers = JSONField(
+    http_method = models.CharField(
-        null=True,
+        max_length=30,
+        choices=WebhookHttpMethodChoices,
+        default=WebhookHttpMethodChoices.METHOD_POST,
+        verbose_name='HTTP method'
+    )
+    http_content_type = models.CharField(
+        max_length=100,
+        default=HTTP_CONTENT_TYPE_JSON,
+        verbose_name='HTTP content type',
+        help_text='The complete list of official content types is available '
+                  '<a href="https://www.iana.org/assignments/media-types/media-types.xhtml">here</a>.'
+    )
+    additional_headers = models.TextField(
         blank=True,
-        help_text="User supplied headers which should be added to the request in addition to the HTTP content type. "
+        help_text="User-supplied HTTP headers to be sent with the request in addition to the HTTP content type. "
-                  "Headers are supplied as key/value pairs in a JSON object."
+                  "Headers should be defined in the format <code>Name: Value</code>. Jinja2 template processing is "
+                  "support with the same context as the request body (below)."
+    )
+    body_template = models.TextField(
+        blank=True,
+        help_text='Jinja2 template for a custom request body. If blank, a JSON object representing the change will be '
+                  'included. Available context data includes: <code>event</code>, <code>model</code>, '
+                  '<code>timestamp</code>, <code>username</code>, <code>request_id</code>, and <code>data</code>.'
     )
     secret = models.CharField(
         max_length=255,
@@ -101,9 +118,6 @@ class Webhook(models.Model):
                   "the secret as the key. The secret is not transmitted in "
                   "the request."
     )
-    enabled = models.BooleanField(
-        default=True
-    )
     ssl_verification = models.BooleanField(
         default=True,
         verbose_name='SSL verification',
@@ -126,9 +140,6 @@ class Webhook(models.Model):
         return self.name
 
     def clean(self):
-        """
-        Validate model
-        """
         if not self.type_create and not self.type_delete and not self.type_update:
             raise ValidationError(
                 "You must select at least one type: create, update, and/or delete."
@@ -136,14 +147,30 @@ class Webhook(models.Model):
 
         if not self.ssl_verification and self.ca_file_path:
             raise ValidationError({
-                'ca_file_path': 'Do not specify a CA certificate file if SSL verification is dissabled.'
+                'ca_file_path': 'Do not specify a CA certificate file if SSL verification is disabled.'
             })
 
-        # Verify that JSON data is provided as an object
+    def render_headers(self, context):
-        if self.additional_headers and type(self.additional_headers) is not dict:
+        """
-            raise ValidationError({
+        Render additional_headers and return a dict of Header: Value pairs.
-                'additional_headers': 'Header JSON data must be in object form. Example: {"X-API-KEY": "abc123"}'
+        """
-            })
+        if not self.additional_headers:
+            return {}
+        ret = {}
+        data = render_jinja2(self.additional_headers, context)
+        for line in data.splitlines():
+            header, value = line.split(':')
+            ret[header.strip()] = value.strip()
+        return ret
+
+    def render_body(self, context):
+        """
+        Render the body template, if defined. Otherwise, jump the context as a JSON object.
+        """
+        if self.body_template:
+            return render_jinja2(self.body_template, context)
+        else:
+            return json.dumps(context, cls=JSONEncoder)
 
 
 #

netbox/extras/tests/test_webhooks.py

@@ -34,7 +34,7 @@ class WebhookTest(APITestCase):
         DUMMY_SECRET = "LOOKATMEIMASECRETSTRING"
 
         webhooks = Webhook.objects.bulk_create((
-            Webhook(name='Site Create Webhook', type_create=True, payload_url=DUMMY_URL, secret=DUMMY_SECRET, additional_headers={'X-Foo': 'Bar'}),
+            Webhook(name='Site Create Webhook', type_create=True, payload_url=DUMMY_URL, secret=DUMMY_SECRET, additional_headers='X-Foo: Bar'),
             Webhook(name='Site Update Webhook', type_update=True, payload_url=DUMMY_URL, secret=DUMMY_SECRET),
             Webhook(name='Site Delete Webhook', type_delete=True, payload_url=DUMMY_URL, secret=DUMMY_SECRET),
         ))

netbox/extras/webhooks.py

@@ -1,4 +1,3 @@
-import datetime
 import hashlib
 import hmac
 

netbox/extras/webhooks_worker.py

@@ -1,19 +1,21 @@
-import json
+import logging
 
 import requests
 from django_rq import job
-from rest_framework.utils.encoders import JSONEncoder
+from jinja2.exceptions import TemplateError
 
-from .choices import ObjectChangeActionChoices, WebhookContentTypeChoices
+from .choices import ObjectChangeActionChoices
 from .webhooks import generate_signature
 
+logger = logging.getLogger('netbox.webhooks_worker')
+
 
 @job('default')
 def process_webhook(webhook, data, model_name, event, timestamp, username, request_id):
     """
     Make a POST request to the defined Webhook
     """
-    payload = {
+    context = {
         'event': dict(ObjectChangeActionChoices)[event].lower(),
         'timestamp': timestamp,
         'model': model_name,
@@ -21,29 +23,48 @@ def process_webhook(webhook, data, model_name, event, timestamp, username, reque
         'request_id': request_id,
         'data': data
     }
+
+    # Build the headers for the HTTP request
     headers = {
         'Content-Type': webhook.http_content_type,
     }
-    if webhook.additional_headers:
+    try:
-        headers.update(webhook.additional_headers)
+        headers.update(webhook.render_headers(context))
+    except (TemplateError, ValueError) as e:
+        logger.error("Error parsing HTTP headers for webhook {}: {}".format(webhook, e))
+        raise e
 
+    # Render the request body
+    try:
+        body = webhook.render_body(context)
+    except TemplateError as e:
+        logger.error("Error rendering request body for webhook {}: {}".format(webhook, e))
+        raise e
+
+    # Prepare the HTTP request
     params = {
-        'method': 'POST',
+        'method': webhook.http_method,
         'url': webhook.payload_url,
-        'headers': headers
+        'headers': headers,
+        'data': body,
     }
+    logger.info(
+        "Sending {} request to {} ({} {})".format(
+            params['method'], params['url'], context['model'], context['event']
+        )
+    )
+    logger.debug(params)
+    try:
+        prepared_request = requests.Request(**params).prepare()
+    except requests.exceptions.RequestException as e:
+        logger.error("Error forming HTTP request: {}".format(e))
+        raise e
 
-    if webhook.http_content_type == WebhookContentTypeChoices.CONTENTTYPE_JSON:
+    # If a secret key is defined, sign the request with a hash of the key and its content
-        params.update({'data': json.dumps(payload, cls=JSONEncoder)})
-    elif webhook.http_content_type == WebhookContentTypeChoices.CONTENTTYPE_FORMDATA:
-        params.update({'data': payload})
-
-    prepared_request = requests.Request(**params).prepare()
-
     if webhook.secret != '':
-        # Sign the request with a hash of the secret key and its content.
         prepared_request.headers['X-Hook-Signature'] = generate_signature(prepared_request.body, webhook.secret)
 
+    # Send the request
     with requests.Session() as session:
         session.verify = webhook.ssl_verification
         if webhook.ca_file_path:
@@ -51,8 +72,10 @@ def process_webhook(webhook, data, model_name, event, timestamp, username, reque
         response = session.send(prepared_request)
 
     if 200 <= response.status_code <= 299:
+        logger.info("Request succeeded; response status {}".format(response.status_code))
         return 'Status {} returned, webhook successfully processed.'.format(response.status_code)
     else:
+        logger.warning("Request failed; response status {}: {}".format(response.status_code, response.content))
         raise requests.exceptions.RequestException(
             "Status {} returned with content '{}', webhook FAILED to process.".format(
                 response.status_code, response.content