追踪 PydanticAI

​PydanticAI 是一个 Python 框架，旨在简化生产级生成式 AI 应用程序的开发。它为生成式 AI 应用开发带来了类型安全、符合人体工程学的 API 设计和开发者友好的体验。

MLflow Tracing 为 ​PydanticAI（一个用于构建多代理应用程序的开源框架）提供了自动追踪能力。通过调用 mlflow.pydantic_ai.autolog() 函数启用 PydanticAI 的自动追踪后，MLflow 将捕获 PydanticAI 工作流执行的嵌套追踪，并将其记录到当前的 MLflow 实验中。

import mlflow

mlflow.pydantic_ai.autolog()

MLflow 追踪自动捕获有关 PydanticAI 代理的以下信息

• 代理调用，包括提示、kwargs 和输出响应
• LLM 请求，记录模型名称、提示、参数和响应
• 工具运行，捕获工具名称、参数和使用指标
• MCP 服务器调用和列表，用于工具调用追踪
• Span 元数据：延迟、错误和运行 ID 关联

注意

目前，MLflow 的 PydanticAI 集成支持同步和异步执行的追踪，但尚不支持流式操作。

示例用法

首先，为 PydanticAI 启用自动追踪，并可选择创建一个 MLflow 实验来写入追踪。这有助于更好地组织您的追踪。

import mlflow

# Turn on auto tracing by calling mlflow.pydantic_ai.autolog()
mlflow.pydantic_ai.autolog()


# Optional: Set a tracking URI and an experiment
mlflow.set_tracking_uri("https://:5000")
mlflow.set_experiment("PydanticAI")

接下来，让我们使用 PydanticAI 定义一个多代理工作流。下面的示例设置了一个天气代理，用户可以查询多个地点的天气，代理将使用 get_lat_lng 工具获取这些地点的经纬度，然后使用 get_weather 工具获取这些地点的天气。

import os
from dataclasses import dataclass
from typing import Any

from httpx import AsyncClient

from pydantic_ai import Agent, ModelRetry, RunContext


@dataclass
class Deps:
    client: AsyncClient
    weather_api_key: str | None
    geo_api_key: str | None


weather_agent = Agent(
    # Switch to your favorite LLM
    "google-gla:gemini-2.0-flash",
    # 'Be concise, reply with one sentence.' is enough for some models (like openai) to use
    # the below tools appropriately, but others like anthropic and gemini require a bit more direction.
    system_prompt=(
        "Be concise, reply with one sentence."
        "Use the `get_lat_lng` tool to get the latitude and longitude of the locations, "
        "then use the `get_weather` tool to get the weather."
    ),
    deps_type=Deps,
    retries=2,
    instrument=True,
)


@weather_agent.tool
async def get_lat_lng(
    ctx: RunContext[Deps], location_description: str
) -> dict[str, float]:
    """Get the latitude and longitude of a location.

    Args:
        ctx: The context.
        location_description: A description of a location.
    """
    if ctx.deps.geo_api_key is None:
        return {"lat": 51.1, "lng": -0.1}

    params = {
        "q": location_description,
        "api_key": ctx.deps.geo_api_key,
    }
    r = await ctx.deps.client.get("https://geocode.maps.co/search", params=params)
    r.raise_for_status()
    data = r.json()

    if data:
        return {"lat": data[0]["lat"], "lng": data[0]["lon"]}
    else:
        raise ModelRetry("Could not find the location")


@weather_agent.tool
async def get_weather(ctx: RunContext[Deps], lat: float, lng: float) -> dict[str, Any]:
    """Get the weather at a location.

    Args:
        ctx: The context.
        lat: Latitude of the location.
        lng: Longitude of the location.
    """

    if ctx.deps.weather_api_key is None:
        return {"temperature": "21 °C", "description": "Sunny"}

    params = {
        "apikey": ctx.deps.weather_api_key,
        "location": f"{lat},{lng}",
        "units": "metric",
    }
    r = await ctx.deps.client.get(
        "https://api.tomorrow.io/v4/weather/realtime", params=params
    )
    r.raise_for_status()
    data = r.json()

    values = data["data"]["values"]
    # https://docs.tomorrow.io/reference/data-layers-weather-codes
    code_lookup = {
        1000: "Clear, Sunny",
        1100: "Mostly Clear",
        1101: "Partly Cloudy",
        1102: "Mostly Cloudy",
        1001: "Cloudy",
        2000: "Fog",
        2100: "Light Fog",
        4000: "Drizzle",
        4001: "Rain",
        4200: "Light Rain",
        4201: "Heavy Rain",
        5000: "Snow",
        5001: "Flurries",
        5100: "Light Snow",
        5101: "Heavy Snow",
        6000: "Freezing Drizzle",
        6001: "Freezing Rain",
        6200: "Light Freezing Rain",
        6201: "Heavy Freezing Rain",
        7000: "Ice Pellets",
        7101: "Heavy Ice Pellets",
        7102: "Light Ice Pellets",
        8000: "Thunderstorm",
    }
    return {
        "temperature": f'{values["temperatureApparent"]:0.0f}°C',
        "description": code_lookup.get(values["weatherCode"], "Unknown"),
    }


async def main():
    async with AsyncClient() as client:
        weather_api_key = os.getenv("WEATHER_API_KEY")
        geo_api_key = os.getenv("GEO_API_KEY")
        deps = Deps(
            client=client, weather_api_key=weather_api_key, geo_api_key=geo_api_key
        )
        result = await weather_agent.run(
            "What is the weather like in London and in Wiltshire?", deps=deps
        )
        print("Response:", result.output)


# If you are running this on a notebook
await main()

# Uncomment this is you are using an IDE or Python script.
# asyncio.run(main())

高级示例：利用 MCP 服务器

MLflow Tracing 自动捕获 PydanticAI 中来自 MCP 服务器的工具相关交互，包括 call_tool 和 list_tools 操作。这些操作会作为独立的 span 记录在追踪 UI 中。

以下示例演示了如何在启用 MLflow 追踪的情况下，使用 PydanticAI 运行 MCP 服务器。所有工具调用和列表操作都会自动捕获为 UI 中的追踪 span，并附带相关元数据。

import mlflow
import asyncio

mlflow.set_tracking_uri("https://:5000")
mlflow.set_experiment("MCP Server")
mlflow.pydantic_ai.autolog()

from pydantic_ai import Agent
from pydantic_ai.mcp import MCPServerStdio

server = MCPServerStdio(
    "deno",
    args=[
        "run",
        "-N",
        "-R=node_modules",
        "-W=node_modules",
        "--node-modules-dir=auto",
        "jsr:@pydantic/mcp-run-python",
        "stdio",
    ],
)

agent = Agent("openai:gpt-4o", mcp_servers=[server], instrument=True)


async def main():
    async with agent.run_mcp_servers():
        result = await agent.run("How many days between 2000-01-01 and 2025-03-18?")
    print(result.output)
    # > There are 9,208 days between January 1, 2000, and March 18, 2025.


# If you are running this on a notebook
await main()

# Uncomment this is you are using an IDE or Python script.
# asyncio.run(main())

禁用自动跟踪

通过调用 mlflow.pydantic_ai.autolog(disable=True) 或 mlflow.autolog(disable=True)，可以全局禁用 PydanticAI 的自动追踪。