Fix content-type of /api response (#287)

* Fix content-type of /api response

* Add to changelog

* Reduce footprint of openapi fix

Author: moradology

CHANGES.md

@@ -12,6 +12,7 @@
 
 * The minimum `limit` value for searches is now 1 ([#296](https://github.com/stac-utils/stac-fastapi/pull/296))
 * Links stored with Collections and Items (e.g. license links) are now returned with those STAC objects ([#282](https://github.com/stac-utils/stac-fastapi/pull/282))
+* Content-type response headers for the /api endpoint now reflect those expected in the STAC api spec ([#287](https://github.com/stac-utils/stac-fastapi/pull/287))
 
 ## [2.2.0]
 

stac_fastapi/api/stac_fastapi/api/app.py

@@ -22,6 +22,7 @@
     SearchGetRequest,
     _create_request_model,
 )
+from stac_fastapi.api.openapi import update_openapi
 from stac_fastapi.api.routes import create_async_endpoint, create_sync_endpoint
 
 # TODO: make this module not depend on `stac_fastapi.extensions`
@@ -64,8 +65,10 @@ class StacApi:
     )
     app: FastAPI = attr.ib(
         default=attr.Factory(
-            lambda self: FastAPI(openapi_url=self.settings.openapi_url), takes_self=True
-        )
+            lambda self: FastAPI(openapi_url=self.settings.openapi_url),
+            takes_self=True,
+        ),
+        converter=update_openapi,
     )
     router: APIRouter = attr.ib(default=attr.Factory(APIRouter))
     title: str = attr.ib(default="stac-fastapi")

stac_fastapi/api/stac_fastapi/api/openapi.py

@@ -1,11 +1,45 @@
 """openapi."""
 from fastapi import FastAPI
 from fastapi.openapi.utils import get_openapi
+from starlette.requests import Request
+from starlette.responses import JSONResponse
 
 from stac_fastapi.api.config import ApiExtensions
 from stac_fastapi.types.config import ApiSettings
 
 
+class VndOaiResponse(JSONResponse):
+    """JSON with custom, vendor content-type."""
+
+    media_type = "application/vnd.oai.openapi+json;version=3.0"
+
+
+def update_openapi(app: FastAPI) -> FastAPI:
+    """Update OpenAPI response content-type.
+
+    This function modifies the openapi route to comply with the STAC API spec's
+    required content-type response header
+    """
+    urls = (server_data.get("url") for server_data in app.servers)
+    server_urls = {url for url in urls if url}
+
+    async def openapi(req: Request) -> JSONResponse:
+        root_path = req.scope.get("root_path", "").rstrip("/")
+        if root_path not in server_urls:
+            if root_path and app.root_path_in_servers:
+                app.servers.insert(0, {"url": root_path})
+                server_urls.add(root_path)
+        return VndOaiResponse(app.openapi())
+
+    # Remove the default openapi route
+    app.router.routes = list(
+        filter(lambda r: r.path != app.openapi_url, app.router.routes)
+    )
+    # Add the updated openapi route
+    app.add_route(app.openapi_url, openapi, include_in_schema=False)
+    return app
+
+
 # TODO: Remove or fix, this is currently unused
 # and calls a missing method on ApiSettings
 def config_openapi(app: FastAPI, settings: ApiSettings):

stac_fastapi/pgstac/tests/api/test_api.py

@@ -23,6 +23,15 @@
 ]
 
 
+@pytest.mark.asyncio
+async def test_api_headers(app_client):
+    resp = await app_client.get("/api")
+    assert (
+        resp.headers["content-type"] == "application/vnd.oai.openapi+json;version=3.0"
+    )
+    assert resp.status_code == 200
+
+
 @pytest.mark.asyncio
 async def test_core_router(api_client):
     core_routes = set(STAC_CORE_ROUTES)

stac_fastapi/sqlalchemy/tests/api/test_api.py

@@ -23,6 +23,14 @@
 ]
 
 
+def test_api_headers(app_client):
+    resp = app_client.get("/api")
+    assert (
+        resp.headers["content-type"] == "application/vnd.oai.openapi+json;version=3.0"
+    )
+    assert resp.status_code == 200
+
+
 def test_core_router(api_client):
     core_routes = set(STAC_CORE_ROUTES)
     api_routes = set(