Implementing LLM Gateway and Multi-Tenant Environment Architecture

A space to learn the following:

• Configure a LiteLLM proxy server to provide a single, unified interface between OpenAI API and vLLM, and implement fallback routing rules
• Develop an authorization logic that logically separates tenant (departmental) requests through FastAPI middleware and API Key Header validation
• Implement Token Bucket-based Rate Limiting by writing a Lua script that atomically executes Redis's INCRBY and EXPIRE commands
• Implement defensive logic to block traffic surges (Noisy Neighbor) from specific departments at the API frontend using HTTP 429 status code and Retry-After header
• Implement an asynchronous observability pipeline that logs prompt token usage without user response delay by integrating FastAPI's BackgroundTasks with the Langfuse SDK
• Write logic to extract input/output token amounts from LLM API response metadata, map them to tenant IDs, and process them into a chargeback JSON schema