Prefer simple JSON when possible

fixes: #1370
Generated-by: gpt-5.6-luna

Author: gerrod3

CHANGES/1370.bugfix

@@ -0,0 +1 @@
+Prefer the PyPI Simple API JSON response when clients such as pip and uv advertise JSON alongside HTML.

pulp_python/app/pypi/views.py

@@ -318,8 +318,17 @@ def get_renderers(self):
         Uses custom renderers for PyPI Simple API endpoints, defaulting to standard ones.
         """
         if self.action in ["list", "retrieve"]:
-            # Ordered by priority if multiple content types are present
-            return [TemplateHTMLRenderer(), PyPISimpleHTMLRenderer(), PyPISimpleJSONRenderer()]
+            # DRF resolves equally-specific media types in renderer order and does not
+            # account for q-values.  Put the PyPI JSON renderer first when the client
+            # explicitly advertises it (as pip and uv do), otherwise retain HTML as the
+            # default for browser and legacy clients.
+            accept = self.request.META.get("HTTP_ACCEPT", "").lower()
+            renderers = [TemplateHTMLRenderer(), PyPISimpleHTMLRenderer()]
+            if PYPI_SIMPLE_V1_JSON in accept:
+                renderers.insert(0, PyPISimpleJSONRenderer())
+            else:
+                renderers.append(PyPISimpleJSONRenderer())
+            return renderers
         else:
             return [JSONRenderer(), BrowsableAPIRenderer()]
 

pulp_python/tests/functional/api/test_pypi_simple_api.py

@@ -169,8 +169,8 @@ def test_simple_json_detail_api(
         (PYPI_TEXT_HTML, PYPI_TEXT_HTML),
         (PYPI_SIMPLE_V1_HTML, PYPI_SIMPLE_V1_HTML),
         (PYPI_SIMPLE_V1_JSON, PYPI_SIMPLE_V1_JSON),
-        # Follows defined ordering (html, pypi html, pypi json)
-        (f"{PYPI_SIMPLE_V1_JSON}, {PYPI_SIMPLE_V1_HTML}", PYPI_SIMPLE_V1_HTML),
+        # Clients such as pip and uv advertise JSON first, with HTML as a fallback.
+        (f"{PYPI_SIMPLE_V1_JSON}, {PYPI_SIMPLE_V1_HTML}", PYPI_SIMPLE_V1_JSON),
         # Everything else should be html
         ("", PYPI_TEXT_HTML),
         ("application/json", PYPI_TEXT_HTML),
@@ -191,3 +191,5 @@ def test_simple_api_content_headers(
         response = requests.get(url, headers={"Accept": header})
         assert response.status_code == 200
         assert result in response.headers["Content-Type"]
+        if url == detail_url and result == PYPI_SIMPLE_V1_JSON:
+            assert all(file["upload-time"] for file in response.json()["files"])

pulp_python/tests/functional/api/test_simple_cache.py

@@ -91,14 +91,13 @@ def test_simple_cache_separate_accept_headers(synced_distro):
 
 
 @pytest.mark.parallel
-def test_simple_cache_format_json_does_not_poison_html(synced_distro):
+def test_simple_cache_negotiated_media_types_are_separate(synced_distro):
     """
-    A ?format=json response must not poison a later request with the same Accept.
+    JSON and HTML responses must not poison each other in the cache.
 
-    Clients like uv/pip send an Accept that allows both JSON and HTML. DRF's
-    ?format=json overrides negotiation to JSON, while the same Accept without
-    that query param selects HTML. Caching must key on the negotiated type so
-    the JSON entry is not served (and re-rendered) for the HTML request.
+    Clients like uv/pip send an Accept that allows both JSON and HTML. The
+    negotiated JSON response must be cached separately from an explicit HTML
+    response.
     """
     url = f"{urljoin(synced_distro.base_url, 'simple/')}aiohttp"
     # pip/uv-style Accept: JSON preferred, HTML still acceptable
@@ -112,13 +111,13 @@ def test_simple_cache_format_json_does_not_poison_html(synced_distro):
     assert r_json.headers["X-PULP-CACHE"] == "MISS"
     assert r_json.json()["name"] == "aiohttp"
 
-    r_html = requests.get(url, headers=headers)
+    r_html = requests.get(url, headers={"Accept": PYPI_TEXT_HTML})
     assert r_html.status_code == 200
     assert PYPI_TEXT_HTML in r_html.headers["Content-Type"]
     assert r_html.headers["X-PULP-CACHE"] == "MISS"
     assert b"<a href=" in r_html.content
 
-    r_html_hit = requests.get(url, headers=headers)
+    r_html_hit = requests.get(url, headers={"Accept": PYPI_TEXT_HTML})
     assert r_html_hit.status_code == 200
     assert r_html_hit.headers["X-PULP-CACHE"] == "HIT"
     assert PYPI_TEXT_HTML in r_html_hit.headers["Content-Type"]