[Bug]: Langfuse HTTP headers never reach Langfuse API

[Cyberes]

What happened?

A continuation of #7604.

I am trying to send the header langfuse_trace_user_id.

It works fine when going directly to the LiteLLM server:

curl --location --request POST 'http://192.168.1.114:4000/chat/completions' \
    --header 'Content-Type: application/json' \
    --header 'Authorization: Bearer sk-xxx' \
    --header 'langfuse_trace_user_id: user-id3' \
    --data '{
    "model": "gpt-4o",
    "messages": [
        {
        "role": "user",
        "content": "what llm are you"
        }
    ]
}'

But doesn't when going through nginx:

curl --location --request POST 'https://192.168.1.114:443/chat/completions' -k \
    --header 'Content-Type: application/json' \
    --header 'Authorization: Bearer sk-xxx' \
    --header 'x_langfuse_trace_user_id: user-id4' \
    --data '{
    "model": "gpt-4o",
    "messages": [
        {
        "role": "user",
        "content": "what llm are you"
        }
    ]
}'

This doesn't work either:

curl --location --request POST 'https://192.168.1.114:443/chat/completions' -k \
    --header 'Content-Type: application/json' \
    --header 'Authorization: Bearer sk-xxx' \
    --header 'x-langfuse-trace-user-id: user-id4' \
    --data '{
    "model": "gpt-4o",
    "messages": [
        {
        "role": "user",
        "content": "what llm are you"
        }
    ]
}'

I have tried underscores_in_headers on;

Relevant log output

Are you a ML Ops Team?

No

What LiteLLM version are you on ?

Latest from Docker

Twitter / LinkedIn details

No response

[Cyberes]

Wait, it's sort of working for Librechat to LiteLLM.

version: 1.2.8
cache: true
endpoints:
  custom:
    - name: "Self-Hosted"
      apiKey: "sk-xxx"
      baseURL: "https://llm.xxx.com/v1"
      models:
        default: ["gpt-4o"]
        fetch: true
      titleConvo: true
      summarize: false
      headers:
        x_langfuse_trace_user_id: "LibreChat {{LIBRECHAT_USER_EMAIL}}"

It logged about 5 requests but stopped working after I restarted the container. I can't get it working again

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[Cyberes]

Hey wait I want it open