Fix reloading the environment if there is an error

This adds a new error field to the environment. This is now checked
against when attempting to delete the environment as if there is an
error the handler is never set to initialized.

Note that the property has only been added to SubprocessHandler as
the BlueskyHandler ABC is likely to be removed.

Fixes #512.

docs/reference/openapi.yaml

@@ -37,12 +37,21 @@ components:
       additionalProperties: false
       description: State of internal environment.
       properties:
+        error:
+          description: Error starting blueapi context
+          title: Error
+          type: boolean
+        error_message:
+          description: Contains error message if environment could not be initalized
+          title: Error Message
+          type: string
         initialized:
           description: blueapi context initialized
           title: Initialized
           type: boolean
       required:
       - initialized
+      - error
       title: EnvironmentResponse
       type: object
     HTTPValidationError:

src/blueapi/service/handler.py

@@ -8,7 +8,12 @@
 from blueapi.messaging import StompMessagingTemplate
 from blueapi.messaging.base import MessagingTemplate
 from blueapi.service.handler_base import BlueskyHandler
-from blueapi.service.model import DeviceModel, PlanModel, WorkerTask
+from blueapi.service.model import (
+    DeviceModel,
+    EnvironmentResponse,
+    PlanModel,
+    WorkerTask,
+)
 from blueapi.worker.event import TaskStatusEnum, WorkerState
 from blueapi.worker.reworker import TaskWorker
 from blueapi.worker.task import Task
@@ -143,8 +148,10 @@ def get_task_by_id(self, task_id: str) -> TrackableTask | None:
         return self._worker.get_task_by_id(task_id)
 
     @property
-    def initialized(self) -> bool:
-        return self._initialized
+    def initialized(self) -> EnvironmentResponse:
+        return EnvironmentResponse(
+            initialized=self._initialized, error=False, error_message=None
+        )
 
 
 HANDLER: Handler | None = None

src/blueapi/service/handler_base.py

@@ -1,6 +1,11 @@
 from abc import ABC, abstractmethod
 
-from blueapi.service.model import DeviceModel, PlanModel, WorkerTask
+from blueapi.service.model import (
+    DeviceModel,
+    EnvironmentResponse,
+    PlanModel,
+    WorkerTask,
+)
 from blueapi.worker.event import TaskStatusEnum, WorkerState
 from blueapi.worker.task import Task
 from blueapi.worker.worker import TrackableTask
@@ -103,7 +108,7 @@ def stop(self):
 
     @property
     @abstractmethod
-    def initialized(self) -> bool:
+    def initialized(self) -> EnvironmentResponse:
         """Handler initialization state"""
 
 

src/blueapi/service/main.py

@@ -88,7 +88,7 @@ async def on_key_error_404(_: Request, __: KeyError):
 def get_environment(
     handler: BlueskyHandler = Depends(get_handler),
 ) -> EnvironmentResponse:
-    return EnvironmentResponse(initialized=handler.initialized)
+    return handler.initialized
 
 
 @app.delete("/environment")
@@ -100,7 +100,7 @@ def restart_handler(handler: BlueskyHandler):
         handler.stop()
         handler.start()
 
-    if handler.initialized:
+    if handler.initialized.initialized or handler.initialized.error:
         background_tasks.add_task(restart_handler, handler)
 
 

src/blueapi/service/model.py

@@ -144,3 +144,7 @@ class EnvironmentResponse(BlueapiBaseModel):
     """
 
     initialized: bool = Field(description="blueapi context initialized")
+    error: bool = Field(description="Error starting blueapi context")
+    error_message: str | None = Field(
+        description="Contains error message if environment could not be initalized"
+    )

src/blueapi/service/subprocess_handler.py

@@ -7,7 +7,12 @@
 from blueapi.config import ApplicationConfig
 from blueapi.service.handler import get_handler, setup_handler, teardown_handler
 from blueapi.service.handler_base import BlueskyHandler, HandlerNotStartedError
-from blueapi.service.model import DeviceModel, PlanModel, WorkerTask
+from blueapi.service.model import (
+    DeviceModel,
+    EnvironmentResponse,
+    PlanModel,
+    WorkerTask,
+)
 from blueapi.worker.event import TaskStatusEnum, WorkerState
 from blueapi.worker.task import Task
 from blueapi.worker.worker import TrackableTask
@@ -25,6 +30,8 @@ class SubprocessHandler(BlueskyHandler):
     _config: ApplicationConfig
     _subprocess: PoolClass | None
     _initialized: bool = False
+    _error: bool = False
+    _error_message: str | None = None
 
     def __init__(
         self,
@@ -39,7 +46,12 @@ def start(self):
             self._subprocess.apply(
                 logging.basicConfig, kwds={"level": self._config.logging.level}
             )
-            self._subprocess.apply(setup_handler, [self._config])
+            try:
+                self._subprocess.apply(setup_handler, [self._config])
+            except Exception as e:
+                self._error = True
+                self._error_message = f"Error starting blueapi: {e}"
+                return
             self._initialized = True
 
     def stop(self):
@@ -48,6 +60,8 @@ def stop(self):
             self._subprocess.apply(teardown_handler)
             self._subprocess.close()
             self._subprocess.join()
+            self._error = False
+            self._error_message = None
             self._subprocess = None
 
     def reload_context(self):
@@ -113,8 +127,12 @@ def get_task_by_id(self, task_id: str) -> TrackableTask | None:
         return self._run_in_subprocess(get_task_by_id, [task_id])
 
     @property
-    def initialized(self) -> bool:
-        return self._initialized
+    def initialized(self) -> EnvironmentResponse:
+        return EnvironmentResponse(
+            initialized=self._initialized,
+            error=self._error,
+            error_message=self._error_message,
+        )
 
 
 # Free functions (passed to subprocess) for each of the methods required by Handler

tests/service/test_rest_api.py

@@ -515,7 +515,7 @@ def test_current_complete_returns_400(
 
 
 def test_get_environment(handler: Handler, client: TestClient) -> None:
-    assert client.get("/environment").json() == {"initialized": False}
+    assert client.get("/environment").json() == {"initialized": False, "error": False}
 
 
 def test_delete_environment(handler: Handler, client: TestClient) -> None:

tests/service/test_subprocess_handler.py

@@ -3,7 +3,12 @@
 import pytest
 
 from blueapi.service.handler_base import BlueskyHandler, HandlerNotStartedError
-from blueapi.service.model import DeviceModel, PlanModel, WorkerTask
+from blueapi.service.model import (
+    DeviceModel,
+    EnvironmentResponse,
+    PlanModel,
+    WorkerTask,
+)
 from blueapi.service.subprocess_handler import SubprocessHandler
 from blueapi.worker.event import TaskStatusEnum, WorkerState
 from blueapi.worker.task import Task
@@ -128,7 +133,7 @@ def stop(self): ...
     # Initialized is a special case as it is not delegated
     # Tested by test_initialize
     @property
-    def initialized(self) -> bool:
+    def initialized(self) -> EnvironmentResponse:
         raise Exception("Not implemented")