Unable to connect to RDS Proxy

asyncpg=0.26.0
postgres=13.4

We're trying to connect to RDS through and RDS proxy with IAM auth and it doesn't work. We've verified that the provided code works fine when connecting straight to the database with IAM auth. We've also tested that we can connect through the proxy to the database. The only piece that does not work is asyncpg. This also works when using aiopg.

EDIT:
I suspect that it's something with SSL but we've gotten nowhere pretty fast on it. The logs on RDS Proxy don't say anything other than Internal Error which is very.... unhelpful.

import asyncio
import aiopg
import asyncpg
import boto3
import os
import sys
import ssl
import certifi
from urllib.parse import quote_plus


ENDPOINT="<our proxy url>"
PORT="5432"
USER="<our user>"
REGION="us-east-1"
DBNAME="<our db>"

session = boto3.Session(profile_name='profile')
client = session.client('rds')
token = client.generate_db_auth_token(DBHostname=ENDPOINT, Port=PORT, DBUsername=USER, Region=REGION) # type: ignore


async def main():
    try:
        print("trying connection")
        conn = await asyncpg.connect(dsn=f"postgres://{USER}:{quote_plus(token)}@{ENDPOINT}:5432/{DBNAME}?sslmode=require&sslrootcert=./AmazonRootCA1.pem")
        #conn = await asyncpg.connect(user=USER, password=quote_plus(token), database=DBNAME, host=ENDPOINT, ssl='require')
        print("connected, trying query")
        print(await conn.fetch("SELECT 'connected'"))
    except Exception as e:
        print("CAUSE", e.__cause__)
        raise

    # async with aiopg.connect(f'dbname={DBNAME} user={USER} password={token} host={ENDPOINT} sslmode=require') as conn:
    #     async with conn.cursor() as cur:
    #         await cur.execute("SELECT 'connected'")

    #         async for row in cur:
    #             print(row)

asyncio.run(main())

The error we get back is

Traceback (most recent call last):
  File "/tmp/test/__init__.py", line 50, in <module>
    asyncio.run(main())
  File "/usr/lib/python3.10/asyncio/runners.py", line 44, in run
    return loop.run_until_complete(main)
  File "/usr/lib/python3.10/asyncio/base_events.py", line 646, in run_until_complete
    return future.result()
  File "/tmp/test/__init__.py", line 35, in main
    conn = await asyncpg.connect(dsn=f"postgres://{USER}:{quote_plus(token)}@{ENDPOINT}:5432/{DBNAME}?sslmode=require&sslrootcert=./AmazonRootCA1.pem")
  File "/home/charles/.local/lib/python3.10/site-packages/asyncpg/connection.py", line 2093, in connect
    return await connect_utils._connect(
  File "/home/charles/.local/lib/python3.10/site-packages/asyncpg/connect_utils.py", line 889, in _connect
    return await _connect_addr(
  File "/home/charles/.local/lib/python3.10/site-packages/asyncpg/connect_utils.py", line 776, in _connect_addr
    return await __connect_addr(params, timeout, False, *args)
  File "/home/charles/.local/lib/python3.10/site-packages/asyncpg/connect_utils.py", line 839, in __connect_addr
    await compat.wait_for(connected, timeout=timeout)
  File "/home/charles/.local/lib/python3.10/site-packages/asyncpg/compat.py", line 66, in wait_for
    return await asyncio.wait_for(fut, timeout)
  File "/usr/lib/python3.10/asyncio/tasks.py", line 445, in wait_for
    return fut.result()
asyncpg.exceptions.ConnectionDoesNotExistError: connection was closed in the middle of operation```

首先，使用 asyncpg 0.26.0 针对 RDS Proxy 运行提供的 Python 复现程序，然后跟踪经过 asyncpg.connect 和 asyncpg.connect_utils._connect 的连接路径。将其经过 IAM 身份验证的 SSL 连接与正常工作的直接 PostgreSQL 和 aiopg 连接进行比较。完成的标准是确定 asyncpg 是否可以通过代理进行连接，并记录或修正失败行为。