Add alert groups external URLs information to details API (#4226)

Alert groups connected to an external source will return external URLs
information, eg.

```
{
  "external_urls": [
    {
      "integration": "C2IFSTV93NQUW",
      "integration_type": "servicenow",
      "external_id": "4c686e1e83d1021075feb3a6feaad3a8",
      "url": "https://some.service-now.com/incident.do?sys_id=4c686e1e83d1021075feb3a6feaad3a8"
    }
  ]
}

```
Related to https://github.com/grafana/oncall-private/issues/2615

engine/apps/api/serializers/alert_group.py

@@ -22,6 +22,13 @@ logger = logging.getLogger(__name__)
 logger.setLevel(logging.DEBUG)
 
 
+class ExternalURL(typing.TypedDict):
+    integration: str
+    integration_type: str
+    external_id: str
+    url: str
+
+
 class RenderForWeb(typing.TypedDict):
     title: str
     message: str
@@ -213,6 +220,7 @@ class AlertGroupSerializer(AlertGroupListSerializer):
     alerts = serializers.SerializerMethodField("get_limited_alerts")
     last_alert_at = serializers.SerializerMethodField()
     paged_users = serializers.SerializerMethodField()
+    external_urls = serializers.SerializerMethodField()
 
     class Meta(AlertGroupListSerializer.Meta):
         fields = AlertGroupListSerializer.Meta.fields + [
@@ -221,6 +229,7 @@ class AlertGroupSerializer(AlertGroupListSerializer):
             "slack_permalink",  # TODO: make plugin frontend use "permalinks" field to get Slack link
             "last_alert_at",
             "paged_users",
+            "external_urls",
         ]
 
     def get_last_alert_at(self, obj: "AlertGroup") -> datetime.datetime:
@@ -242,3 +251,21 @@ class AlertGroupSerializer(AlertGroupListSerializer):
 
     def get_paged_users(self, obj: "AlertGroup") -> typing.List[PagedUser]:
         return obj.get_paged_users()
+
+    def get_external_urls(self, obj: "AlertGroup") -> typing.List[ExternalURL]:
+        external_urls = []
+        external_ids = obj.external_ids.all()
+        for external_id in external_ids:
+            source_integration = external_id.source_alert_receive_channel
+            get_url = getattr(source_integration.config, "get_url", None)
+            if get_url:
+                url = source_integration.config.get_url(source_integration, external_id.value)
+                external_urls.append(
+                    {
+                        "integration": source_integration.public_primary_key,
+                        "integration_type": source_integration.integration,
+                        "external_id": external_id.value,
+                        "url": url,
+                    }
+                )
+        return external_urls

engine/apps/api/tests/test_alert_group.py

@@ -1,5 +1,5 @@
 import datetime
-from unittest.mock import patch
+from unittest.mock import Mock, patch
 
 import pytest
 from django.core.cache import cache
@@ -10,7 +10,13 @@ from rest_framework.response import Response
 from rest_framework.test import APIClient
 
 from apps.alerts.constants import ActionSource
-from apps.alerts.models import AlertGroup, AlertGroupLogRecord, ResolutionNote
+from apps.alerts.models import (
+    AlertGroup,
+    AlertGroupExternalID,
+    AlertGroupLogRecord,
+    AlertReceiveChannel,
+    ResolutionNote,
+)
 from apps.alerts.paging import direct_paging
 from apps.alerts.tasks import wipe
 from apps.api.errors import AlertGroupAPIError
@@ -2243,3 +2249,42 @@ def test_alert_group_list_labels(
     assert response.json()["results"][-1]["labels"] == [
         {"key": {"id": "a", "name": "a"}, "value": {"id": "b", "name": "b"}}
     ]
+
+
+@pytest.mark.django_db
+def test_alert_group_external_urls(
+    make_organization_and_user_with_plugin_token,
+    make_user_auth_headers,
+    make_alert_receive_channel,
+    make_alert_receive_channel_connection,
+    make_alert_group,
+):
+    client = APIClient()
+
+    integration_config = AlertReceiveChannel._config[0]
+    integration_config.get_url = Mock(return_value="https://some-url")
+
+    organization, user, token = make_organization_and_user_with_plugin_token()
+    source_alert_receive_channel = make_alert_receive_channel(organization, integration=integration_config.slug)
+    alert_receive_channel = make_alert_receive_channel(organization)
+    make_alert_receive_channel_connection(source_alert_receive_channel, alert_receive_channel)
+
+    alert_group = make_alert_group(alert_receive_channel)
+
+    url = reverse("api-internal:alertgroup-detail", kwargs={"pk": alert_group.public_primary_key})
+    response = client.get(url, format="json", **make_user_auth_headers(user, token))
+    assert response.json()["external_urls"] == []
+
+    # create external IDs
+    external_id = AlertGroupExternalID.objects.create(
+        source_alert_receive_channel=source_alert_receive_channel, alert_group=alert_group, value="test123"
+    )
+    url = reverse("api-internal:alertgroup-detail", kwargs={"pk": alert_group.public_primary_key})
+    response = client.get(url, format="json", **make_user_auth_headers(user, token))
+    expected = {
+        "integration": source_alert_receive_channel.public_primary_key,
+        "integration_type": source_alert_receive_channel.integration,
+        "external_id": external_id.value,
+        "url": "https://some-url",
+    }
+    assert response.json()["external_urls"] == [expected]

grafana-plugin/src/network/oncall-api/autogenerated-api.types.d.ts

@@ -1411,6 +1411,12 @@ export interface components {
         avatar_full: string;
         important: boolean;
       }[];
+      readonly external_urls: {
+        integration: string;
+        integration_type: string;
+        external_id: string;
+        url: string;
+      }[];
     };
     AlertGroupAttach: {
       root_alert_group_pk: string;