Add support for $SLUG placeholder in webhook payloads

Fixes: #1049

CHANGELOG.md

@@ -10,6 +10,7 @@ All notable changes to this project will be documented in this file.
 - Update timezone dropdowns to show frequently used timezones at the top
 - Update the "Set Password" page to reject very weak passwords
 - Implement search by slug in the checks list (#1048)
+- Add support for $SLUG placeholder in webhook payloads (#1049)
 
 ### Bug Fixes
 - Fix Check.ping() to lock the check before updating (#1023)

hc/api/tests/test_notify_webhook.py

@@ -133,19 +133,20 @@ class NotifyWebhookTestCase(BaseTestCase):
     def test_webhooks_support_variables(self, mock_get: Mock) -> None:
         definition = {
             "method_down": "GET",
-            "url_down": "http://host/$CODE/$STATUS/$TAG1/$TAG2/?name=$NAME",
+            "url_down": "http://host/$CODE/$SLUG/$STATUS/$TAG1/$TAG2/?name=$NAME",
             "body_down": "",
             "headers_down": {},
         }
 
         self._setup_data(json.dumps(definition))
         self.check.name = "Hello World"
+        self.check.slug = "hello-world"
         self.check.tags = "foo bar"
         self.check.save()
 
         self.channel.notify(self.flip)
 
-        url = "http://host/%s/down/foo/bar/?name=Hello%%20World" % self.check.code
+        url = f"http://host/{self.check.code}/hello-world/down/foo/bar/?name=Hello%20World"
 
         args, kwargs = mock_get.call_args
         self.assertEqual(args[0], "get")

hc/api/transports.py

@@ -345,6 +345,7 @@ class Webhook(HttpTransport):
             "$NOW": safe(flip.created.replace(microsecond=0).isoformat()),
             "$NAME_JSON": safe(json.dumps(check.name)),
             "$NAME": safe(check.name),
+            "$SLUG": check.slug,
             "$TAGS": safe(check.tags),
             "$JSON": safe(json.dumps(check.to_dict())),
         }

templates/integrations/webhook_form.html

@@ -211,6 +211,10 @@
                             <pre>{"name": $NAME_JSON}</pre>
                         </td>
                     </tr>
+                    <tr>
+                        <th><code>$SLUG</code></th>
+                        <td>Check's slug.</td>
+                    </tr>
                     <tr>
                         <th><code>$NOW</code></th>
                         <td>