feat(api): add deprecation headers to releng legacy JSON endpoint

Add `deprecated_json_endpoint` decorator in `api/deprecation.py` (RFC 8594).
Apply to `releng/views.py` `releases_json` - response now includes
`Deprecation: true` and `Link: </api/v1/releng/releases/>; rel="successor-version"`.

Author: inglor

api/deprecation.py

@@ -0,0 +1,13 @@
+from functools import wraps
+
+
+def deprecated_json_endpoint(successor_path: str):
+    def decorator(view_func):
+        @wraps(view_func)
+        def wrapper(request, *args, **kwargs):
+            response = view_func(request, *args, **kwargs)
+            response['Deprecation'] = 'true'
+            response['Link'] = f'<{successor_path}>; rel="successor-version"'
+            return response
+        return wrapper
+    return decorator

api/tests/test_deprecation.py

@@ -0,0 +1,5 @@
+def test_releng_releases_json_deprecation_headers(db, client):
+    response = client.get('/releng/releases/json/')
+    assert response.status_code == 200
+    assert response['Deprecation'] == 'true'
+    assert response['Link'] == '</api/v1/releng/releases/>; rel="successor-version"'

releng/views.py

@@ -8,6 +8,7 @@
 from django.urls import reverse
 from django.views.generic import DetailView, ListView
 
+from api.deprecation import deprecated_json_endpoint
 from main.models import Package
 from mirrors.models import MirrorUrl
 
@@ -59,6 +60,7 @@ def default(self, obj):
         return super(ReleaseJSONEncoder, self).default(obj)
 
 
+@deprecated_json_endpoint('/api/v1/releng/releases/')
 def releases_json(request):
     releases = Release.objects.all()
     try: