fix: extension stop background work (#2281)

* feat: add helper methods

* fix: do not try to stop background work on first install

* fix: first stop via function call then try REST API

* fix: `make check`

* fix: prepare for `{ext_id}_stop`

lnbits/core/helpers.py

@@ -53,8 +53,45 @@ async def stop_extension_background_work(
 ):
     """
     Stop background work for extension (like asyncio.Tasks, WebSockets, etc).
-    Extensions SHOULD expose a DELETE enpoint at the root level of their API.
+    Extensions SHOULD expose a `api_stop()` function and/or a DELETE enpoint
+    at the root level of their API.
     """
+    stopped = await _stop_extension_background_work(ext_id)
+
+    if not stopped:
+        # fallback to REST API call
+        await _stop_extension_background_work_via_api(ext_id, user, access_token)
+
+
+async def _stop_extension_background_work(ext_id) -> bool:
+    upgrade_hash = settings.extension_upgrade_hash(ext_id) or ""
+    ext = Extension(ext_id, True, False, upgrade_hash=upgrade_hash)
+
+    try:
+        logger.info(f"Stopping background work for extension '{ext.module_name}'.")
+        old_module = importlib.import_module(ext.module_name)
+
+        # Extensions must expose an `{ext_id}_stop()` function at the module level
+        # The `api_stop()` function is for backwards compatibility (will be deprecated)
+        stop_fns = [f"{ext_id}_stop", "api_stop"]
+        stop_fn_name = next((fn for fn in stop_fns if hasattr(old_module, fn)), None)
+        assert stop_fn_name, "No stop function found for '{ext.module_name}'"
+
+        await getattr(old_module, stop_fn_name)()
+
+        logger.info(f"Stopped background work for extension '{ext.module_name}'.")
+    except Exception as ex:
+        logger.warning(f"Failed to stop background work for '{ext.module_name}'.")
+        logger.warning(ex)
+        return False
+
+    return True
+
+
+async def _stop_extension_background_work_via_api(ext_id, user, access_token):
+    logger.info(
+        f"Stopping background work for extension '{ext_id}' using the REST API."
+    )
     async with httpx.AsyncClient() as client:
         try:
             url = f"http://{settings.host}:{settings.port}/{ext_id}/api/v1?usr={user}"
@@ -63,7 +100,11 @@ async def stop_extension_background_work(
             )
             resp = await client.delete(url=url, headers=headers)
             resp.raise_for_status()
+            logger.info(f"Stopped background work for extension '{ext_id}'.")
         except Exception as ex:
+            logger.warning(
+                f"Failed to stop background work for '{ext_id}' using the REST API."
+            )
             logger.warning(ex)