add simplified test endpoint

python/lsst/daf/butler/remote_butler/server/handlers/_external_query.py

@@ -62,6 +62,25 @@
 query_router = APIRouter()
 
 
+@query_router.get("/v1/test-thing")
+def test_thing() -> StreamingResponse:
+    return StreamingResponse(
+        _whatever(),
+        media_type="application/jsonlines",
+        headers={
+            # Instruct the Kubernetes ingress to not buffer the response,
+            # so that keep-alives reach the client promptly.
+            "X-Accel-Buffering": "no"
+        },
+    )
+
+
+async def _whatever() -> AsyncIterator:
+    while True:
+        await asyncio.sleep(1)
+        yield '{ "type": "keep-alive" }\n'
+
+
 @query_router.post("/v1/query/execute", summary="Query the Butler database and return full results")
 def query_execute(
     request: QueryExecuteRequestModel, factory: Factory = Depends(factory_dependency)