feat: Introduce validate_task_params endpoint

src/blueapi/service/interface.py

@@ -18,6 +18,7 @@
     PlanModel,
     PythonEnvironmentResponse,
     SourceInfo,
+    TaskParamsValidationRequest,
     TaskRequest,
     WorkerTask,
 )
@@ -172,6 +173,22 @@ def submit_task(
     return worker().submit_task(task)
 
 
+def validate_task_params(
+    task_request: TaskParamsValidationRequest, metadata: dict[str, Any] | None = None
+) -> bool:
+    """Validate the params for a task"""
+    # Can't default arg to mutable data structure:
+    if metadata is None:
+        metadata = {}
+
+    task = Task(
+        name=task_request.name,
+        params=task_request.params,
+        metadata=metadata,
+    )
+    return worker().validate_task_params(task)
+
+
 def clear_task(task_id: str) -> str:
     """Remove a task from the worker"""
     return worker().clear_task(task_id)

src/blueapi/service/main.py

@@ -51,9 +51,11 @@
     PythonEnvironmentResponse,
     SourceInfo,
     StateChangeRequest,
+    TaskParamsValidationRequest,
     TaskRequest,
     TaskResponse,
     TasksListResponse,
+    TasksParamValidationResponse,
     WorkerTask,
 )
 from .runner import WorkerDispatcher
@@ -327,6 +329,64 @@ def submit_task(
         ) from e
 
 
+example_task_validate_params_request = TaskParamsValidationRequest(
+    name="count",
+    params={"detectors": ["x"]},
+)
+
+
+@secure_router_v1.post(
+    "/validateTaskParams", status_code=status.HTTP_200_OK, tags=[Tag.TASK]
+)
+@start_as_current_span(
+    TRACER,
+    "request",
+    "task_request.name",
+    "task_request.params",
+)
+def validate_task_params(
+    request: Request,
+    response: Response,
+    task_request: Annotated[
+        TaskParamsValidationRequest, Body(..., examples=[example_task_request])
+    ],
+    runner: Annotated[WorkerDispatcher, Depends(_runner)],
+) -> TasksParamValidationResponse:
+    """Validate the tasks parameters."""
+    try:
+        # Extract user from jwt if using OIDC (if jwt exists)
+        access_token: dict[str, Any] | None = getattr(
+            request.state, "decoded_access_token", None
+        )
+        if access_token:
+            user: str = access_token.get("fedid", "Unknown")
+        else:
+            user = "Unknown"
+
+        validated: bool = runner.run(
+            interface.validate_task_params, task_request, {"user": user}
+        )
+        return TasksParamValidationResponse(validated=validated)
+    except ValidationError as e:
+        # Add body/params context to location and ensure that all required
+        # fields defined in the generated schema are present
+        errors = [
+            {
+                "loc": ["body", "params", *err.get("loc", [])],
+                "msg": err.get("msg", None),
+                "type": err.get("type", None),
+                # Input is not listed as required but is useful to have if available
+                "input": err.get("input", None),
+            }
+            for err in e.errors()
+        ]
+
+        raise HTTPException(
+            status_code=status.HTTP_422_UNPROCESSABLE_ENTITY,
+            detail=errors,
+        ) from e
+
+
 @secure_router_v1.delete(
     "/tasks/{task_id}", status_code=status.HTTP_200_OK, tags=[Tag.TASK]
 )

src/blueapi/service/model.py

@@ -58,6 +58,16 @@ class TasksListResponse(BlueapiBaseModel):
     tasks: list[TrackableTask] = Field(description="List of tasks")
 
 
+class TasksParamValidationResponse(BlueapiBaseModel):
+    """
+    Diagnostic information on the tasks
+    """
+
+    validated: bool = Field(
+        description="Whether the task params were sucessfully validated"
+    )
+
+
 class TaskRequest(BlueapiBaseModel):
     """
     Request to run a task with related info
@@ -72,6 +82,17 @@ class TaskRequest(BlueapiBaseModel):
     )
 
 
+class TaskParamsValidationRequest(BlueapiBaseModel):
+    """
+    Request to validate the parameters of a task
+    """
+
+    name: str = Field(description="Name of plan to run")
+    params: Mapping[str, Any] = Field(
+        description="Values for parameters to plan, if any", default_factory=dict
+    )
+
+
 class DeviceRequest(BlueapiBaseModel):
     """
     A query for devices

src/blueapi/worker/task_worker.py

@@ -292,6 +292,18 @@ def submit_task(self, task: Task) -> str:
         self._pending_tasks[task_id] = trackable_task
         return task_id
 
+    @start_as_current_span(TRACER, "task.name", "task.params")
+    def validate_task_params(self, task: Task) -> bool:
+        """
+        Validates the params for a task
+        Args:
+            task: A description of the task
+        Returns:
+            bool: True of the params are validated
+        """
+        task.prepare_params(self._ctx)  # Will raise if parameters are invalid
+        return True
+
     @start_as_current_span(
         TRACER,
         "trackable_task.task_id",