feat: add authz dependency injection

src/blueapi/service/authentication.py

@@ -272,3 +272,12 @@ def get_access_token(self):
     def sync_auth_flow(self, request):
         request.headers["Authorization"] = f"Bearer {self.get_access_token()}"
         yield request
+
+
+class OPAClient:  # placeholder until https://jira.diamond.ac.uk/browse/ACQP-550 is done
+    def do_some_checks(self, task_request) -> bool:
+        return True
+
+
+def get_opa_client() -> OPAClient:  # placeholder
+    return OPAClient()

src/blueapi/service/main.py

@@ -37,6 +37,7 @@
 from blueapi import __version__
 from blueapi.config import ApplicationConfig, OIDCConfig, Tag
 from blueapi.service import interface
+from blueapi.service.authentication import OPAClient, get_opa_client
 from blueapi.worker import TrackableTask, WorkerState
 from blueapi.worker.event import TaskStatusEnum
 
@@ -166,6 +167,16 @@ def inner(request: Request, access_token: str = Depends(oauth_scheme)):
 TRACER = get_tracer("interface")
 
 
+def submit_permission(
+    opa: Annotated[OPAClient, Depends(get_opa_client)],
+    task_request: TaskRequest,
+):
+    allowed = opa.do_some_checks(task_request)
+
+    if not allowed:
+        raise HTTPException(status_code=status.HTTP_403_FORBIDDEN)
+
+
 async def on_key_error_404(_: Request, __: Exception):
     return JSONResponse(
         status_code=status.HTTP_404_NOT_FOUND,
@@ -291,6 +302,7 @@ def submit_task(
     request: Request,
     response: Response,
     task_request: Annotated[TaskRequest, Body(..., examples=[example_task_request])],
+    _: Annotated[None, Depends(submit_permission)],
     runner: Annotated[WorkerDispatcher, Depends(_runner)],
 ) -> TaskResponse:
     """Submit a task to the worker."""
@@ -336,6 +348,7 @@ def submit_task(
 @start_as_current_span(TRACER, "task_id")
 def delete_submitted_task(
     task_id: str,
+    _: Annotated[None, Depends(submit_permission)],
     runner: Annotated[WorkerDispatcher, Depends(_runner)],
 ) -> TaskResponse:
     return TaskResponse(task_id=runner.run(interface.clear_task, task_id))
@@ -354,6 +367,7 @@ def validate_task_status(v: str) -> TaskStatusEnum:
 @start_as_current_span(TRACER)
 def get_tasks(
     runner: Annotated[WorkerDispatcher, Depends(_runner)],
+    _: Annotated[None, Depends(submit_permission)],
     task_status: str | SkipJsonSchema[None] = None,
 ) -> TasksListResponse:
     """
@@ -390,6 +404,7 @@ def get_tasks(
 def set_active_task(
     request: Request,
     task: WorkerTask,
+    _: Annotated[None, Depends(submit_permission)],
     runner: Annotated[WorkerDispatcher, Depends(_runner)],
 ) -> WorkerTask:
     """Set a task to active status, the worker should begin it as soon as possible.
@@ -420,6 +435,7 @@ def get_passthrough_headers(request: Request) -> dict[str, str]:
 @start_as_current_span(TRACER, "task_id")
 def get_task(
     task_id: str,
+    _: Annotated[None, Depends(submit_permission)],
     runner: Annotated[WorkerDispatcher, Depends(_runner)],
 ) -> TrackableTask:
     """Retrieve a task"""
@@ -497,6 +513,7 @@ def get_state(runner: Annotated[WorkerDispatcher, Depends(_runner)]) -> WorkerSt
 def set_state(
     state_change_request: StateChangeRequest,
     response: Response,
+    _: Annotated[None, Depends(submit_permission)],
     runner: Annotated[WorkerDispatcher, Depends(_runner)],
 ) -> WorkerState:
     """