auth failed when start mongo with --auth

SUMMARY

when i set a password for mongo with
MONGO_INITDB_ROOT_USERNAME
MONGO_INITDB_ROOT_PASSWORD

docker run -d --network some-network --name some-mongo
-e MONGO_INITDB_ROOT_USERNAME=mongoadmin
-e MONGO_INITDB_ROOT_PASSWORD=secret
mongo

and i add username and password in st2.conf

[database]
host = mongo
connection_retry_max_delay_m = 1
connection_retry_backoff_mul = 1
connection_timeout = 3000
username = mongoadmin
password = secret

but the st2 run with auth error

st2api | File "/opt/stackstorm/st2/lib/python3.6/site-packages/pymongo/mongo_client.py", line 781, in _cache_credentials
st2api | sock_info.authenticate(credentials)
st2api | File "/opt/stackstorm/st2/lib/python3.6/site-packages/pymongo/pool.py", line 810, in authenticate
st2api | auth.authenticate(credentials, self)
st2api | File "/opt/stackstorm/st2/lib/python3.6/site-packages/pymongo/auth.py", line 673, in authenticate
st2api | auth_func(credentials, sock_info)
st2api | File "/opt/stackstorm/st2/lib/python3.6/site-packages/pymongo/auth.py", line 591, in _authenticate_default
st2api | return _authenticate_scram(credentials, sock_info, 'SCRAM-SHA-1')
st2api | File "/opt/stackstorm/st2/lib/python3.6/site-packages/pymongo/auth.py", line 295, in _authenticate_scram
st2api | res = sock_info.command(source, cmd)
st2api | File "/opt/stackstorm/st2/lib/python3.6/site-packages/pymongo/pool.py", line 694, in command
st2api | exhaust_allowed=exhaust_allowed)
st2api | File "/opt/stackstorm/st2/lib/python3.6/site-packages/pymongo/network.py", line 161, in command
st2api | parse_write_concern_error=parse_write_concern_error)
st2api | File "/opt/stackstorm/st2/lib/python3.6/site-packages/pymongo/helpers.py", line 164, in _check_command_response
st2api | raise OperationFailure(errmsg, code, response, max_wire_version)
st2api | pymongo.errors.OperationFailure: Authentication failed., full error: {'ok': 0.0, 'errmsg': 'Authentication failed.', 'code': 18, 'codeName': 'AuthenticationFailed'}

STACKSTORM VERSION

3.6.0

OS, environment, install method

docker-compose

i think the root cause is missing authentication_source='admin' when connect to mongodb, but i can't find where to set this config.

i checked the source code, and found the code not use this parameter.

in this file, line 188
st2-3.6.0/st2common/st2common/models/db/init.py

should add authentication_source parameter
connection = mongoengine.connection.connect(
db_name,
host=db_host,
port=db_port,
tz_aware=True,
username=username,
password=password,
connectTimeoutMS=connection_timeout,
serverSelectionTimeoutMS=connection_timeout,
**ssl_kwargs,
**compressor_kwargs,
)

The issue points to st2common/st2common/models/db/init.py and its mongoengine.connection.connect call; start by tracing how the [database] values in st2.conf reach that call. Check the MongoDB authentication behavior described in the issue and the surrounding database tests or entry points. Done means a MongoDB instance initialized with the documented root credentials can authenticate successfully through StackStorm.