llm-infer 0.4.0

A readable LLM inference server implementing paged attention and continuous batching

llm-infer

Unified CLI and client library for local LLM inference. Wraps Ollama, vLLM, and a native engine behind a single interface.

Components:

• CLI & Server - Single command to serve models via Ollama, vLLM, or native torch engine
• Client Package - Standard interface to multiple LLM backends (OpenAI, Anthropic, local servers)
• Native Engine - Custom torch implementation for learning and experimentation

Quick Start

pip install llm-infer

# With Ollama (https://ollama.com)
ollama pull qwen2.5:0.5b
llm-infer serve --model qwen2.5:0.5b

# Query
llm-infer query "What is the capital of France?"

Client Package

llm_infer.client is a Python client library for LLM inference with a unified interface across backends. Built for autonomous agents and production use:

• Multiple backends - OpenAI, Anthropic, and any OpenAI-compatible API
• Sync, async, streaming - All execution modes supported
• Rate limiting - Per-backend request throttling
• Retry with backoff - Configurable exponential backoff on failures
• Model routing - Route requests to backends by model name
• Extensible - Register custom backends via Factory.register()

from appinfra.log import Logger
from llm_infer.client import Factory

lg = Logger("my-app")
factory = Factory(lg)

with factory.openai(base_url="http://localhost:8000/v1") as client:
    response = client.chat(
        messages=[{"role": "user", "content": "Hello!"}],
        system="You are a helpful assistant.",
    )
    print(response.content)

# Streaming
with factory.openai(base_url="http://localhost:8000/v1") as client:
    messages = [{"role": "user", "content": "Hello!"}]
    for token in client.chat_stream(messages):
        print(token, end="", flush=True)

# Async
async with factory.openai(base_url="http://localhost:8000/v1") as client:
    messages = [{"role": "user", "content": "Hello!"}]
    response = await client.chat_async(messages)

Protocol Extensions

The server extends the OpenAI chat completions API:

Request - adds think and adapter fields:

{
  "model": "default",
  "messages": [{"role": "user", "content": "What is 15 * 23?"}],
  "think": true,
  "adapter": "my-lora-adapter"
}

Response - adds thinking in message and adapter metadata:

{
  "id": "chatcmpl-123",
  "choices": [{
    "message": {
      "role": "assistant",
      "content": "345",
      "thinking": "Let me calculate step by step..."
    }
  }],
  "adapter": {
    "requested": "my-lora-adapter",
    "actual": "my-lora-adapter",
    "fallback": false
  }
}

The client library exposes these as keyword arguments:

response = client.chat(messages, think=True, adapter="my-adapter")
print(response.thinking)  # Reasoning content
print(response.content)   # Final answer

Multiple Backends

# Anthropic
async with factory.anthropic(model="claude-sonnet-4-20250514") as client:
    response = await client.chat_async(messages)

# OpenAI
with factory.openai(base_url="https://api.openai.com/v1", api_key="sk-...") as client:
    response = client.chat(messages)

Engines

Engine	Description	Install
ollama (default)	Wraps Ollama server	ollama.com
vllm	vLLM Python API	pip install vllm
vllm-server	vLLM HTTP subprocess	pip install vllm
native	Custom torch implementation	pip install llm-infer[runtime]

llm-infer serve --model qwen2.5:7b                          # Ollama
llm-infer serve --engine vllm --model-path /path/to/model   # vLLM
llm-infer serve --engine native --model-path /path/to/model # Native

Native Engine

The native engine is a from-scratch torch implementation with PagedAttention and FlashInfer. Useful for learning how LLM inference works or experimenting with custom modifications.

pip install llm-infer[runtime]
llm-infer serve --engine native --model-path /path/to/model

Configuration

# etc/llm-infer.yaml
backends:
  engine: ollama

models:
  locations:
    - /path/to/models
  selection:
    generate:
      default: qwen2.5-7b
    embed:
      default: bge-small-en-v1.5

api:
  host: 0.0.0.0
  port: 8000

Per-model overrides in etc/models.yaml:

models:
  qwen2.5-7b:
    max_model_len: 8192
    vllm:
      enforce_eager: true

  qwen2.5:7b:
    ollama: qwen2.5:7b  # Ollama model name mapping

API Endpoints

Endpoint	Description
POST /v1/chat/completions	Chat completion (OpenAI-compatible)
POST /v1/completions	Text completion (OpenAI-compatible)
GET /v1/models	List available models
GET /health	Health check
GET /metrics	Prometheus metrics

Installation

pip install llm-infer              # Client only
pip install llm-infer[anthropic]   # With Anthropic support
pip install llm-infer[saia]        # With llm-saia integration
pip install llm-infer[runtime]     # With native engine (torch)

License

Apache License 2.0