fix: pass root_path to FastAPI constructor instead of uvicorn

When lightspeed-stack runs behind 3scale with ROOT_PATH=/api/lightspeed,
requests arrive with a doubled path prefix because uvicorn injects
root_path into scope['root_path'] and Starlette concatenates it with
the already-prefixed scope['path'] from 3scale.

Move root_path from uvicorn.run() to the FastAPI() constructor, matching
how rlsapi handles it.

Signed-off-by: Major Hayden <major@redhat.com>

Author: major

src/app/main.py

@@ -84,6 +84,7 @@ async def lifespan(_app: FastAPI) -> AsyncIterator[None]:
 
 
 app = FastAPI(
+    root_path=configuration.service_configuration.root_path,
     title=f"{service_name} service - OpenAPI",
     summary=f"{service_name} service API specification.",
     description=f"{service_name} service API specification.",

src/runners/uvicorn.py

@@ -16,7 +16,7 @@ def start_uvicorn(configuration: ServiceConfiguration) -> None:
 
     Parameters:
         configuration (ServiceConfiguration): Configuration providing host,
-        port, workers, `root_path`, and `tls_config` (including `tls_key_path`,
+        port, workers, and `tls_config` (including `tls_key_path`,
         `tls_certificate_path`, and `tls_key_password`). TLS fields may be None
         and will be forwarded to uvicorn.run as provided.
     """
@@ -31,7 +31,6 @@ def start_uvicorn(configuration: ServiceConfiguration) -> None:
         host=configuration.host,
         port=configuration.port,
         workers=configuration.workers,
-        root_path=configuration.root_path,
         log_level=log_level,
         ssl_keyfile=configuration.tls_config.tls_key_path,
         ssl_certfile=configuration.tls_config.tls_certificate_path,

tests/unit/runners/test_uvicorn_runner.py

@@ -10,9 +10,7 @@
 
 def test_start_uvicorn(mocker: MockerFixture) -> None:
     """Test the function to start Uvicorn server using de-facto default configuration."""
-    configuration = ServiceConfiguration(
-        host="localhost", port=8080, workers=1
-    )  # pyright: ignore[reportCallIssue]
+    configuration = ServiceConfiguration(host="localhost", port=8080, workers=1)  # pyright: ignore[reportCallIssue]
 
     # don't start real Uvicorn server
     mocked_run = mocker.patch("uvicorn.run")
@@ -22,7 +20,6 @@ def test_start_uvicorn(mocker: MockerFixture) -> None:
         host="localhost",
         port=8080,
         workers=1,
-        root_path="",
         log_level=20,
         ssl_certfile=None,
         ssl_keyfile=None,
@@ -34,9 +31,7 @@ def test_start_uvicorn(mocker: MockerFixture) -> None:
 
 def test_start_uvicorn_different_host_port(mocker: MockerFixture) -> None:
     """Test the function to start Uvicorn server using custom configuration."""
-    configuration = ServiceConfiguration(
-        host="x.y.com", port=1234, workers=10
-    )  # pyright: ignore[reportCallIssue]
+    configuration = ServiceConfiguration(host="x.y.com", port=1234, workers=10)  # pyright: ignore[reportCallIssue]
 
     # don't start real Uvicorn server
     mocked_run = mocker.patch("uvicorn.run")
@@ -46,7 +41,6 @@ def test_start_uvicorn_different_host_port(mocker: MockerFixture) -> None:
         host="x.y.com",
         port=1234,
         workers=10,
-        root_path="",
         log_level=20,
         ssl_certfile=None,
         ssl_keyfile=None,
@@ -71,7 +65,6 @@ def test_start_uvicorn_empty_tls_configuration(mocker: MockerFixture) -> None:
         host="x.y.com",
         port=1234,
         workers=10,
-        root_path="",
         log_level=20,
         ssl_certfile=None,
         ssl_keyfile=None,
@@ -100,7 +93,6 @@ def test_start_uvicorn_tls_configuration(mocker: MockerFixture) -> None:
         host="x.y.com",
         port=1234,
         workers=10,
-        root_path="",
         log_level=20,
         ssl_certfile=Path("tests/configuration/server.crt"),
         ssl_keyfile=Path("tests/configuration/server.key"),
@@ -111,7 +103,7 @@ def test_start_uvicorn_tls_configuration(mocker: MockerFixture) -> None:
 
 
 def test_start_uvicorn_with_root_path(mocker: MockerFixture) -> None:
-    """Test the function to start Uvicorn server with a custom root path."""
+    """Test that root_path is not passed to uvicorn (it belongs on the FastAPI constructor)."""
     configuration = ServiceConfiguration(
         host="localhost", port=8080, workers=1, root_path="/api/lightspeed"
     )  # pyright: ignore[reportCallIssue]
@@ -124,7 +116,6 @@ def test_start_uvicorn_with_root_path(mocker: MockerFixture) -> None:
         host="localhost",
         port=8080,
         workers=1,
-        root_path="/api/lightspeed",
         log_level=20,
         ssl_certfile=None,
         ssl_keyfile=None,