discord.py（带Cogs）+FastAPI：域名解析失败及优雅终止问题

初始问题：errno -3 temporary failure in name resolution错误 #

尝试在FastAPI中启动一个基础discord.py机器人时，遭遇errno -3 temporary failure in name resolution错误，相关代码如下：

@typechecked
class UnfilteredBot(Bot):
    async def process_commands(self, message:Message)->None:
        ctx:Context = await self.get_context(message)
        await self.invoke(ctx)

@typechecked
class MyBot(UnfilteredBot):
    def __init__(self, command_prefix:str='!')->None:
        intents: Intents        = Intents.default()
        #intents.members        = True
        # allow to get commands from GC
        intents.message_content = True  # v2
        super().__init__(intents=intents, command_prefix=command_prefix)

@typechecked
def get_app(token:str, guild:str, channel:int, rest_key:str)->FastAPI:
    shutdown         :Event          = Event() # from threading import Event
    #complete         :Event          = Event()
    app              :FastAPI        = FastAPI()
    bot              :Bot            = MyBot()

    @app.on_event("startup")
    async def startup_event()->Coroutine[None]: # this function will run before the main API starts
        bot_start:Coroutine[None] = bot.start(token)
        create_task( bot_start )

    @app.on_event("shutdown")
    async def shutdown_event()->Coroutine[None]:
        shutdown.set()
        #while not complete.wait(1): # gently stop a different bot's loop
        #    await sleep(1) # work-around for follow-up question
        #    print("waiting")
    return app

@typechecked
def main()->None:
    load_dotenv  () # from dotenv import load_dotenv
    token            :str            =     environ['DISCORD_TOKEN']
    guild            :str            =     environ['DISCORD_GUILD']
    channel          :int            = int(environ['DISCORD_CHANNEL'])
    host             :str            =      getenv('HOST', 'locahost') # <-- 问题所在
    port             :int            =      getenv('PORT',       5000)
    setup_logging() # from discord.utils import setup_logging
    app              :FastAPI        = get_app(token, guild, channel, rest_key)
    urun(app, host=host, port=port) # from uvicorn import run as urun

if __name__ == '__main__':
    exit(main())

问题解决说明 #

该错误已解决，原因是host参数拼写错误（locahost应为localhost）。分享此内容是因为目前缺少包含Cogs和优雅终止逻辑的相关示例。

后续疑问：协程环境下的机器人优雅终止问题 #

当前无法优雅终止另一个机器人，原使用的threading.Event方案仅适用于线程环境，在协程环境下循环停止后finally块无法执行，导致FastAPI服务器无法正常关闭。相关代码如下：

async def start(self)->Coroutine[None]:
    try:
        print('AI.start() try')
        while not self.shutdown.wait(1):
            print('AI.start() loop')
            
            await sleep(1) #???
            pass
    finally:
        print('AI.start() finally')
        #self.shutdown.set() # assert is set ?
        self.complete.set()
    print('AI.start() done')

已找到一个基于asyncio.Event的Event_ts实现，但原机器人是适配线程应用开发的，不确定该实现是否适用，需要找到协程环境下实现定时wait()的解决方案。

内容的提问来源于stack exchange，提问作者Innovations Anonymous