feat: Add silence and unsilence public api endpoint (#5031)

# What this PR does
Exposes alert group silence and unsilence via public api endpoint

## Which issue(s) this PR closes
[#5026](https://github.com/grafana/oncall/issues/5026)

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## Checklist

- [x] Unit, integration, and e2e (if applicable) tests updated
- [x] Documentation added (or `pr:no public docs` PR label added if not
required)
- [x] Added the relevant release notes label (see labels prefixed w/
`release:`). These labels dictate how your PR will
    show up in the autogenerated release notes.

docs/sources/oncall-api-reference/alertgroups.md

@@ -130,6 +130,38 @@ curl "{{API_URL}}/api/v1/alert_groups/I68T24C13IFW1/unresolve" \
 
 `POST {{API_URL}}/api/v1/alert_groups/<ALERT_GROUP_ID>/unresolve`
 
+## Silence an alert group
+
+```shell
+curl "{{API_URL}}/api/v1/alert_groups/I68T24C13IFW1/silence" \
+  --request POST \
+  --header "Authorization: meowmeowmeow" \
+  --header "Content-Type: application/json" \
+  --data '{
+      "delay": 10800
+  }'
+```
+
+**HTTP request**
+
+`POST {{API_URL}}/api/v1/alert_groups/<ALERT_GROUP_ID>/silence`
+
+| Parameter | Required | Description                                                                                                                                                                                                                                                                                                                                             |
+|-----------|:--------:|:--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| `delay`    |    Yes    | The duration of silence in seconds, `-1` for silencing the alert forever |
+
+## Unsilence an alert group
+
+```shell
+curl "{{API_URL}}/api/v1/alert_groups/I68T24C13IFW1/unsilence" \
+  --request POST \
+  --header "Authorization: meowmeowmeow"
+```
+
+**HTTP request**
+
+`POST {{API_URL}}/api/v1/alert_groups/<ALERT_GROUP_ID>/unsilence`
+
 ## Delete an alert group
 
 ```shell

engine/apps/public_api/tests/test_alert_groups.py

@@ -635,3 +635,98 @@ def test_alert_group_unresolve(
         alert_group.refresh_from_db()
         assert alert_group.resolved is False
         assert alert_group.log_records.last().action_source == ActionSource.API
+
+
+@pytest.mark.parametrize(
+    "acknowledged,resolved,attached,status_code,data,response_msg",
+    [
+        (False, False, False, status.HTTP_200_OK, {"delay": 60}, None),
+        (False, False, False, status.HTTP_400_BAD_REQUEST, {"delay": -2}, "invalid delay value"),
+        (False, False, False, status.HTTP_400_BAD_REQUEST, {"delay": "fuzz"}, "invalid delay value"),
+        (False, False, False, status.HTTP_400_BAD_REQUEST, {}, "delay is required"),
+        (True, False, False, status.HTTP_400_BAD_REQUEST, {"delay": 60}, "Can't silence an acknowledged alert group"),
+        (False, True, False, status.HTTP_400_BAD_REQUEST, {"delay": 60}, "Can't silence a resolved alert group"),
+        (False, False, True, status.HTTP_400_BAD_REQUEST, {"delay": 60}, "Can't silence an attached alert group"),
+    ],
+)
+@pytest.mark.django_db
+def test_alert_group_silence(
+    make_organization_and_user_with_token,
+    make_alert_receive_channel,
+    make_alert_group,
+    acknowledged,
+    resolved,
+    attached,
+    status_code,
+    data,
+    response_msg,
+):
+    organization, _, token = make_organization_and_user_with_token()
+    alert_receive_channel = make_alert_receive_channel(organization)
+    root_alert_group = make_alert_group(alert_receive_channel)
+    alert_group = make_alert_group(
+        alert_receive_channel,
+        acknowledged=acknowledged,
+        resolved=resolved,
+        root_alert_group=root_alert_group if attached else None,
+    )
+
+    client = APIClient()
+    url = reverse("api-public:alert_groups-silence", kwargs={"pk": alert_group.public_primary_key})
+    response = client.post(url, data=data, HTTP_AUTHORIZATION=token)
+
+    if status_code == status.HTTP_200_OK:
+        alert_group.refresh_from_db()
+        assert alert_group.silenced is True
+        assert alert_group.log_records.last().action_source == ActionSource.API
+    else:
+        assert alert_group.silenced is False
+        assert response.status_code == status_code
+        assert response_msg == response.json()["detail"]
+
+
+@pytest.mark.parametrize(
+    "silenced,resolved,acknowledged,attached,status_code,response_msg",
+    [
+        (True, False, False, False, status.HTTP_200_OK, None),
+        (False, False, False, False, status.HTTP_400_BAD_REQUEST, "Can't unsilence an unsilenced alert group"),
+        (True, True, False, False, status.HTTP_400_BAD_REQUEST, "Can't unsilence a resolved alert group"),
+        (True, False, True, False, status.HTTP_400_BAD_REQUEST, "Can't unsilence an acknowledged alert group"),
+        (True, False, False, True, status.HTTP_400_BAD_REQUEST, "Can't unsilence an attached alert group"),
+    ],
+)
+@pytest.mark.django_db
+def test_alert_group_unsilence(
+    make_organization_and_user_with_token,
+    make_alert_receive_channel,
+    make_alert_group,
+    silenced,
+    resolved,
+    acknowledged,
+    attached,
+    status_code,
+    response_msg,
+):
+    organization, _, token = make_organization_and_user_with_token()
+    alert_receive_channel = make_alert_receive_channel(organization)
+    root_alert_group = make_alert_group(alert_receive_channel)
+    alert_group = make_alert_group(
+        alert_receive_channel,
+        acknowledged=acknowledged,
+        resolved=resolved,
+        silenced=silenced,
+        root_alert_group=root_alert_group if attached else None,
+    )
+
+    client = APIClient()
+    url = reverse("api-public:alert_groups-unsilence", kwargs={"pk": alert_group.public_primary_key})
+    response = client.post(url, HTTP_AUTHORIZATION=token)
+
+    if status_code == status.HTTP_200_OK:
+        alert_group.refresh_from_db()
+        assert alert_group.silenced is False
+        assert alert_group.log_records.last().action_source == ActionSource.API
+    else:
+        assert alert_group.silenced == silenced
+        assert response.status_code == status_code
+        assert response_msg == response.json()["detail"]

engine/apps/public_api/views/alert_groups.py

@@ -213,3 +213,49 @@ class AlertGroupView(
 
         alert_group.un_resolve_by_user_or_backsync(self.request.user, action_source=ActionSource.API)
         return Response(status=status.HTTP_200_OK)
+
+    @action(methods=["post"], detail=True)
+    def silence(self, request, pk=None):
+        alert_group = self.get_object()
+
+        delay = request.data.get("delay")
+        if delay is None:
+            raise BadRequest(detail="delay is required")
+        try:
+            delay = int(delay)
+        except ValueError:
+            raise BadRequest(detail="invalid delay value")
+        if delay < -1:
+            raise BadRequest(detail="invalid delay value")
+
+        if alert_group.resolved:
+            raise BadRequest(detail="Can't silence a resolved alert group")
+
+        if alert_group.acknowledged:
+            raise BadRequest(detail="Can't silence an acknowledged alert group")
+
+        if alert_group.root_alert_group is not None:
+            raise BadRequest(detail="Can't silence an attached alert group")
+
+        alert_group.silence_by_user_or_backsync(request.user, silence_delay=delay, action_source=ActionSource.API)
+        return Response(status=status.HTTP_200_OK)
+
+    @action(methods=["post"], detail=True)
+    def unsilence(self, request, pk=None):
+        alert_group = self.get_object()
+
+        if not alert_group.silenced:
+            raise BadRequest(detail="Can't unsilence an unsilenced alert group")
+
+        if alert_group.resolved:
+            raise BadRequest(detail="Can't unsilence a resolved alert group")
+
+        if alert_group.acknowledged:
+            raise BadRequest(detail="Can't unsilence an acknowledged alert group")
+
+        if alert_group.root_alert_group is not None:
+            raise BadRequest(detail="Can't unsilence an attached alert group")
+
+        alert_group.un_silence_by_user_or_backsync(request.user, action_source=ActionSource.API)
+
+        return Response(status=status.HTTP_200_OK)