将 discord 机器人暴露给 API（Flask，FASTAPI）

Question

I'm building a discord bot to take commands from multiple systems and programs. I'm wanting to expose certain actions of my discord bot to REST endpoints and then execute said actions in one spot.

import uvicorn
from fastapi import FastAPI
from pydantic import BaseModel
from typing import Optional
from discord.ext import commands

app = FastAPI()

TOKEN = 'MY_TOKEN'

bot = commands.Bot(command_prefix='>')

class Item(BaseModel):
    name: str
    description: Optional[str] = None
    price: float
    tax: Optional[float] = None

@app.get("/")
def hello():
    return {"message":"Hello"}

@app.post("/items/")
async def create_item(item: Item):
    await send_message()
    return item

@bot.event
async def on_ready():
    print(f'{bot.user.name} has connected to Discord!')

async def send_message():
    user = await bot.fetch_user(USER_ID)
    await user.send('👀')

if __name__ == "__main__":
    bot.run('BOT_TOKEN')
    uvicorn.run(app, host='0.0.0.0')

When I try to run this, I'm only seeing the bot active. I'm a little newer to python but a veteran programmer. Is this due to python's "lack" of multithreading? Or port usage?

The end goal is to call the "/items/" endpoint and see a message on discord sent to me

EDIT

I tried all the answers and coming up with some of my own. The problem is multi-threading. I got frustrated with it and ended up just moving this piece to Node.js. It doesn't technically fulfill this question but was far easier than navigating python multithreading.

server.js:

var express = require('express');
var app = express();
const Discord = require('discord.js');
const client = new Discord.Client();

app.get('/listUsers', function (req, res) {

    dm_user();

    res.send('hello');
})

client.on('ready', () => {
  console.log(`Logged in as ${client.user.tag}!`);
});

client.on('message', msg => {
  if (msg.content === 'ping') {
    msg.reply('pong');
  }
});

async function dm_user(id){
    var my_user = await client.users.fetch('USER_ID');
    console.log(my_user);
}

var server = app.listen(8081, function () {
   var host = server.address().address
   var port = server.address().port
   console.log("Example app listening at http://%s:%s", host, port)
   client.login('TOKEN');
})

Answer 1

According to the discord.py docs bot.run() is "A blocking call that abstracts away the event loop initialisation from you." and further they said if we want more control over the loop we could use start() coroutine instead of run(). So now we should create a task for calling this coroutine and we know discord.py and FastAPI all are asynchronous applications. For starting a FastAPI app you need an ASGI server to handle it. In this case, we're using Uvicorn . So far we have run FastAPI app, now we need to start our discord bot. According to FastAPI docs we could use startup/shutdown event , for calling bot.start() coroutine before the main API starts.

Here is an example of an app which has an API endpoint for sending a message to a discord's user:

import asyncio
import discord
import uvicorn

from config import TOKEN, USER_ID
from fastapi import FastAPI

app = FastAPI()
bot = discord.Client()

@app.on_event("startup")
async def startup_event(): #this fucntion will run before the main API starts
    asyncio.create_task(bot.start(TOKEN))
    await asyncio.sleep(4) #optional sleep for established connection with discord
    print(f"{bot.user} has connected to Discord!")

@app.get("/")
async def root(msg: str): #API endpoint for sending a message to a discord's user
    user = await send_message(msg)
    return {"Message": f"'{msg}' sent to {user}"}

async def send_message(message):
    user = await bot.fetch_user(USER_ID)
    await user.send(message)
    return user #for optional log in the response of endpoint

if __name__ == "__main__":
    uvicorn.run(app, host="localhost", port=5000)

Tested with Python 3.7.4

Answer 2

You are not returning anything from your send_message function. Something like this should do good.

@app.post("/items/")
async def create_item(item: Item):
    msg = await send_message()
    return msg


async def send_message():
    user = await bot.fetch_user(USER_ID)
    return await user.send('👀')

Answer 3

Code bot.run(...) runs all time and it blocks next line which starts API. You would have to run one of them in separated thread or process.

I tried to run bot in thread

if __name__ == "__main__":
    import threading 

    print('Starting bot')
    t = threading.Thread(target=bot.start, args=(TOKEN,))
    t.start()
    
    print('Starting API')
    uvicorn.run(app, host='0.0.0.0')

but it gives me message that bot should run in main thread.

But I found question Discord bot and bottle in the same time in Python and base on it I create code which works for me

if __name__ == "__main__":
    import asyncio
    
    print('Starting bot')
    bot_app = bot.start(TOKEN)
    bot_task = asyncio.ensure_future(bot_app)
    
    print('Starting API')
    uvicorn.run(app, host='0.0.0.0')

But I'm not sure if this is ellegant method because uvicorn runs ayncio indirectly.

---

Full version

import uvicorn
from fastapi import FastAPI
from pydantic import BaseModel
from typing import Optional
from discord.ext import commands

app = FastAPI()

#import os
#TOKEN = os.getenv("DISCORD_TOKEN")
TOKEN = 'MY_TOKEN'

bot = commands.Bot(command_prefix='>')

class Item(BaseModel):
    name: str
    description: Optional[str] = None
    price: float
    tax: Optional[float] = None

@app.get("/")
def hello():
    return {"message":"Hello"}

@app.post("/items/")
async def create_item(item: Item):
    await send_message()
    return item

@bot.event
async def on_ready():
    print(f'{bot.user.name} has connected to Discord!')

async def send_message():
    user = await bot.fetch_user(USER_ID)
    await user.send('👀')

if __name__ == "__main__":
    import asyncio
        
    print('Starting bot')
    bot_app = bot.start(TOKEN)
    bot_task = asyncio.ensure_future(bot_app)
        
    print('Starting API')
    uvicorn.run(app, host='0.0.0.0')