proxy server miss media_type in streaming mode (#4130)

Author: lvhan028

lmdeploy/serve/proxy/proxy.py

@@ -587,7 +587,7 @@ async def chat_completions_v1(request: ChatCompletionRequest, raw_request: Reque
         if request.stream is True:
             response = node_manager.stream_generate(request_dict, node_url, '/v1/chat/completions')
             background_task = node_manager.create_background_tasks(node_url, start)
-            return StreamingResponse(response, background=background_task)
+            return StreamingResponse(response, background=background_task, media_type='text/event-stream')
         else:
             response = await node_manager.generate(request_dict, node_url, '/v1/chat/completions')
             node_manager.post_call(node_url, start)
@@ -649,7 +649,7 @@ async def chat_completions_v1(request: ChatCompletionRequest, raw_request: Reque
         if request.stream is True:
             response = node_manager.stream_generate(request_dict, d_url, '/v1/chat/completions')
             background_task = node_manager.create_background_tasks(d_url, start)
-            resp = StreamingResponse(response, background=background_task)
+            resp = StreamingResponse(response, background=background_task, media_type='text/event-stream')
         else:
             response = await node_manager.generate(request_dict, d_url, '/v1/chat/completions')
             node_manager.post_call(d_url, start)
@@ -717,7 +717,7 @@ async def completions_v1(request: CompletionRequest, raw_request: Request = None
         if request.stream is True:
             response = node_manager.stream_generate(request_dict, node_url, '/v1/completions')
             background_task = node_manager.create_background_tasks(node_url, start)
-            return StreamingResponse(response, background=background_task)
+            return StreamingResponse(response, background=background_task, media_type='text/event-stream')
         else:
             response = await node_manager.generate(request_dict, node_url, '/v1/completions')
             node_manager.post_call(node_url, start)
@@ -793,7 +793,7 @@ async def completions_v1(request: CompletionRequest, raw_request: Request = None
         if request.stream is True:
             response = node_manager.stream_generate(request_dict, d_url, '/v1/completions')
             background_task = node_manager.create_background_tasks(d_url, start)
-            resp = StreamingResponse(response, background=background_task)
+            resp = StreamingResponse(response, background=background_task, media_type='text/event-stream')
         else:
             response = await node_manager.generate(request_dict, d_url, '/v1/completions')
             node_manager.post_call(d_url, start)