We actually need to implement this via Middleware, as the Locale Middleware comes later in the process and hinders us from removing the header. Anyway, it's cleaner, since we're not duplicating code

config.py

@@ -31,7 +31,7 @@ INSTALLED_APPS.extend(
 
 MIDDLEWARE.extend(
     [
-        "django.middleware.locale.LocaleMiddleware",
+        "ivatar.middleware.RemoveVaryForImagesMiddleware",
     ]
 )
 MIDDLEWARE.insert(

ivatar/middleware.py

@@ -4,6 +4,26 @@ Middleware classes
 """
 
 from django.utils.deprecation import MiddlewareMixin
+from django.middleware.locale import LocaleMiddleware
+
+
+class RemoveVaryForImagesMiddleware(LocaleMiddleware):
+    """
+    Middleware that extends LocaleMiddleware to skip Vary header processing for image URLs
+    """
+
+    def process_response(self, request, response):
+        # Check if this is an image-related URL
+        path = request.path
+        if any(
+            path.startswith(prefix)
+            for prefix in ["/avatar/", "/gravatarproxy/", "/blueskyproxy/"]
+        ):
+            # Skip the parent's process_response to avoid adding Accept-Language to Vary
+            return response
+
+        # For all other URLs, use the parent's behavior
+        return super().process_response(request, response)
 
 
 class MultipleProxyMiddleware(

ivatar/settings.py

@@ -43,7 +43,6 @@ MIDDLEWARE = [
     "django.contrib.auth.middleware.AuthenticationMiddleware",
     "django.contrib.messages.middleware.MessageMiddleware",
     "django.middleware.clickjacking.XFrameOptionsMiddleware",
-    "django.middleware.locale.LocaleMiddleware",
 ]
 
 ROOT_URLCONF = "ivatar.urls"

ivatar/views.py

@@ -125,8 +125,6 @@ class AvatarImageView(TemplateView):
                     reason=centry["reason"],
                     charset=centry["charset"],
                 )
-                # Remove Vary header for images since language doesn't matter
-                response["Vary"] = ""
                 return response
 
         # In case no digest at all is provided, return to home page
@@ -297,8 +295,6 @@ class AvatarImageView(TemplateView):
             imgformat = "jpeg"
         response = CachingHttpResponse(uri, data, content_type=f"image/{imgformat}")
         response["Cache-Control"] = "max-age=%i" % CACHE_IMAGES_MAX_AGE
-        # Remove Vary header for images since language doesn't matter
-        response["Vary"] = ""
         return response
 
     def _redirect_static_w_size(self, arg0, size):
@@ -317,8 +313,6 @@ class AvatarImageView(TemplateView):
         data.seek(0)
         response = CachingHttpResponse(uri, data, content_type="image/png")
         response["Cache-Control"] = "max-age=%i" % CACHE_IMAGES_MAX_AGE
-        # Remove Vary header for images since language doesn't matter
-        response["Vary"] = ""
         return response
 
     def _return_cached_png(self, arg0, data, uri):
@@ -414,8 +408,6 @@ class GravatarProxyView(View):
                 data.read(), content_type=f"image/{file_format(img.format)}"
             )
             response["Cache-Control"] = "max-age=%i" % CACHE_IMAGES_MAX_AGE
-            # Remove Vary header for images since language doesn't matter
-            response["Vary"] = ""
             return response
 
         except ValueError as exc:
@@ -535,8 +527,6 @@ class BlueskyProxyView(View):
                 data.read(), content_type=f"image/{file_format(format)}"
             )
             response["Cache-Control"] = "max-age=%i" % CACHE_IMAGES_MAX_AGE
-            # Remove Vary header for images since language doesn't matter
-            response["Vary"] = ""
             return response
         except ValueError as exc:
             print(f"Value error: {exc}")