feat: events when a model goes online or offline

Webhooks and event functions had no way to know when a model appeared or disappeared from a connection, for example when a vLLM server stops answering. Open WebUI now sends a model online event when a model shows up in the model list and a model offline event when it drops out of it. The events are checked whenever the model list is fetched from the connections, so they are not a live health check. Nothing is sent for the first model list after startup.

backend/open_webui/events.py

@@ -490,6 +490,12 @@ class EventDefinitions(BaseModel):
     MODEL_DISABLED: EventDefinition = EventDefinition(
         name='model.disabled', description='A model was disabled.', message='Model disabled'
     )
+    MODEL_ONLINE: EventDefinition = EventDefinition(
+        name='model.online', description='A model became available.', message='Model online'
+    )
+    MODEL_OFFLINE: EventDefinition = EventDefinition(
+        name='model.offline', description='A model is no longer available.', message='Model offline'
+    )
     MODEL_ACCESS_UPDATED: EventDefinition = EventDefinition(
         name='model.access_updated', description='Model access was updated.', message='Model access updated'
     )

backend/open_webui/main.py

@@ -625,6 +625,7 @@ app.state.SCIM_TOKEN = SCIM_TOKEN
 # Models
 
 app.state.BASE_MODELS = []
+app.state.ONLINE_MODELS = None
 
 # WebUI
 

backend/open_webui/utils/models.py

@@ -9,6 +9,7 @@ from open_webui.config import (
     DEFAULT_ARENA_MODEL,
 )
 from open_webui.env import BYPASS_MODEL_ACCESS_CONTROL, ENABLE_FUNCTIONS, GLOBAL_LOG_LEVEL, REDIS_KEY_PREFIX
+from open_webui.events import EVENTS, publish_event
 from open_webui.functions import get_function_models
 from open_webui.models.access_grants import AccessGrants
 from open_webui.models.config import Config
@@ -90,6 +91,33 @@ async def get_all_base_models(request: Request, user: UserModel = None):
     return function_models + openai_models + ollama_models
 
 
+async def publish_model_status_events(request: Request, base_models: list[dict]):
+    online_models = {model['id']: model.get('name') for model in base_models}
+    previous_models = request.app.state.ONLINE_MODELS
+    request.app.state.ONLINE_MODELS = online_models
+    if previous_models is None:
+        return
+
+    for model_id in sorted(online_models.keys() - previous_models.keys()):
+        await publish_event(
+            request,
+            EVENTS.MODEL_ONLINE,
+            subject_id=model_id,
+            subject_type='model',
+            source='system',
+            data={'name': online_models[model_id]},
+        )
+    for model_id in sorted(previous_models.keys() - online_models.keys()):
+        await publish_event(
+            request,
+            EVENTS.MODEL_OFFLINE,
+            subject_id=model_id,
+            subject_type='model',
+            source='system',
+            data={'name': previous_models[model_id]},
+        )
+
+
 async def get_all_models(request, refresh: bool = False, user: UserModel = None):
     config = await Config.get_many(
         'models.base_models_cache',
@@ -123,6 +151,7 @@ async def get_all_models(request, refresh: bool = False, user: UserModel = None)
 
     if base_models is None:
         base_models = await get_all_base_models(request, user=user)
+        await publish_model_status_events(request, base_models)
         if base_models:
             request.app.state.BASE_MODELS = base_models
             if config.get('models.base_models_cache') and redis is not None: