Modify Nginx config for WebSocket connection handling

Updated the Nginx configuration to handle WebSocket upgrades correctly by using a map for the Connection header.

Author: felixboelter

base/nginx/configmap.yaml

@@ -8,6 +8,17 @@ data:
       worker_connections 1024;
     }
     http {
+      # Only send "Connection: upgrade" when the client actually initiated a
+      # WebSocket upgrade. For plain GETs, send "Connection: close". Required
+      # when an HTTP/2 frontend (Caddy) sits in front of this nginx — HTTP/2
+      # forbids hop-by-hop Connection: upgrade headers and will abort the
+      # response with ERR_HTTP2_PROTOCOL_ERROR otherwise (symptom: JS chunks
+      # fail to load, LiteLLM UI stuck on "Loading...").
+      map $http_upgrade $connection_upgrade {
+        default upgrade;
+        ''      close;
+      }
+
       upstream litellm_backend {
         server litellm-service.litellm.svc.cluster.local:4000;
       }
@@ -34,7 +45,7 @@ data:
 
           # Streaming and WebSocket support
           proxy_set_header Upgrade           $http_upgrade;
-          proxy_set_header Connection        "upgrade";
+          proxy_set_header Connection        $connection_upgrade;
           proxy_buffering                    off;
           proxy_read_timeout                 300s;