feat: check of server and client version in response header (#1443)

Fixes #1074

Check of version headers in the response has been added to the client
side.

---------

Co-authored-by: Zoheb Shaikh <26975142+ZohebShaikh@users.noreply.github.com>

Author: shree-iyengar-dls

src/blueapi/client/rest.py

@@ -1,3 +1,4 @@
+import logging
 from collections.abc import Callable, Mapping
 from typing import Any, Literal, TypeVar
 
@@ -10,6 +11,7 @@
 )
 from pydantic import BaseModel, TypeAdapter, ValidationError
 
+from blueapi import __version__
 from blueapi.config import RestConfig
 from blueapi.service.authentication import JWTAuth, SessionManager
 from blueapi.service.model import (
@@ -32,6 +34,8 @@
 
 TRACER = get_tracer("rest")
 
+LOGGER = logging.getLogger(__name__)
+
 
 class UnauthorisedAccessError(Exception):
     pass
@@ -271,6 +275,17 @@ def _request_and_deserialize(
             raise exception
         if response.status_code == status.HTTP_204_NO_CONTENT:
             raise NoContentError(target_type)
+        if (server_version := response.headers.get("x-blueapi-version")) is not None:
+            from packaging.version import Version
+
+            if (server_version := Version(server_version).base_version) != (
+                client_version := Version(__version__).base_version
+            ):
+                LOGGER.warning(
+                    f"Version mismatch: Blueapi server version is {server_version} "
+                    f"but client version is {client_version}. "
+                    f"Some features may not work as expected."
+                )
         deserialized = TypeAdapter(target_type).validate_python(response.json())
         return deserialized
 

src/blueapi/service/main.py

@@ -34,6 +34,7 @@
 from starlette.responses import JSONResponse
 from super_state_machine.errors import TransitionError
 
+from blueapi import __version__
 from blueapi.config import ApplicationConfig, OIDCConfig, Tag
 from blueapi.service import interface
 from blueapi.worker import TrackableTask, WorkerState
@@ -123,7 +124,7 @@ def get_app(config: ApplicationConfig):
     app.include_router(secure_router, dependencies=dependencies)
     app.add_exception_handler(KeyError, on_key_error_404)
     app.add_exception_handler(jwt.PyJWTError, on_token_error_401)
-    app.middleware("http")(add_api_version_header)
+    app.middleware("http")(add_version_headers)
     app.middleware("http")(inject_propagated_observability_context)
     app.middleware("http")(log_request_details)
     if config.api.cors:
@@ -568,11 +569,12 @@ def start(config: ApplicationConfig):
     )
 
 
-async def add_api_version_header(
+async def add_version_headers(
     request: Request, call_next: Callable[[Request], Awaitable[Response]]
 ):
     response = await call_next(request)
     response.headers["X-API-Version"] = ApplicationConfig.REST_API_VERSION
+    response.headers["X-BlueAPI-Version"] = __version__
     return response
 
 

tests/unit_tests/client/test_rest.py

@@ -1,11 +1,13 @@
 import uuid
 from pathlib import Path
-from unittest.mock import Mock, patch
+from unittest.mock import MagicMock, Mock, patch
 
 import pytest
 import requests
 import responses
+from packaging.version import Version
 
+from blueapi import __version__
 from blueapi.client.rest import (
     BlueapiRestClient,
     BlueskyRemoteControlError,
@@ -196,3 +198,36 @@ def test_parameter_error_other_string():
         input=34,
     )
     assert str(p1) == "Invalid value 34 for field field_one.0: error_message"
+
+
+@pytest.mark.parametrize(
+    "server_version,logging_warning_present",
+    [(__version__, False), ("0.0.1", True), (None, False)],
+)
+@patch("blueapi.client.rest.TypeAdapter")
+@patch("blueapi.client.rest.requests.Session.request")
+@patch("blueapi.client.rest.LOGGER")
+def test_server_and_client_versions(
+    mock_logger: MagicMock,
+    mock_request: Mock,
+    mock_type_adapter: Mock,
+    rest: BlueapiRestClient,
+    server_version: str,
+    logging_warning_present: bool,
+):
+    response = Mock(spec=requests.Response)
+    response.status_code = 200
+    response.headers = {"x-blueapi-version": server_version}
+    mock_request.return_value = response
+
+    rest.get_plans()
+
+    if logging_warning_present:
+        mock_logger.warning.assert_called_once_with(
+            f"Version mismatch: Blueapi server version is "
+            f"{Version(server_version).base_version} "
+            f"but client version is {Version(__version__).base_version}. "
+            f"Some features may not work as expected."
+        )
+    else:
+        mock_logger.assert_not_called()

tests/unit_tests/service/test_main.py

@@ -5,7 +5,28 @@
 from fastapi import FastAPI, Request
 from fastapi.testclient import TestClient
 
-from blueapi.service.main import get_passthrough_headers, log_request_details
+from blueapi import __version__
+from blueapi.config import ApplicationConfig
+from blueapi.service.main import (
+    add_version_headers,
+    get_passthrough_headers,
+    log_request_details,
+)
+
+
+async def test_add_version_header():
+    app = FastAPI()
+    app.middleware("http")(add_version_headers)
+
+    @app.get("/")
+    async def root():
+        return {"message": "Hello World"}
+
+    client = TestClient(app)
+    response = client.get("/")
+
+    assert response.headers["X-API-VERSION"] == ApplicationConfig.REST_API_VERSION
+    assert response.headers["X-BlueAPI-VERSION"] == __version__
 
 
 async def test_log_request_details():