Mongo Python Error :: Troubleshoot an Authentication Error?

Question

In trying to build off of this SO post, I've built the below Python script. It should connect to a remote MongoDB (actually a VM on my local machine), run a simple find() operation, then print the results:

from pymongo import MongoClient
MONGO_HOST = "172.17.0.2"
MONGO_PORT = "27017"
MONGO_DB = "myDB"
MONGO_USER = "me"
MONGO_PASS = "password01"

uri = "mongodb://{}:{}@{}:{}/{}?authSource=admin".format(MONGO_USER, MONGO_PASS, MONGO_HOST, MONGO_PORT, MONGO_DB)

client = MongoClient(uri)    
myDB = client['myDB']
myTable = myDB['TableA']

limited_cursor = myTable.find({ "data1": "KeyStringHere" }, { "_id": 0, "data2" : 1 }).limit(2)
for document in limited_cursor:
    print(document)

When run, the code vomits out a lot of errors:

me@ubuntu1:~/$ /usr/bin/python3 myPythonScript.py
Traceback (most recent call last):
  File "myPythonScript.py", line 14, in <module>
    for document in limited_cursor:
  File "/usr/lib/python3/dist-packages/pymongo/cursor.py", line 1169, in next
    if len(self.__data) or self._refresh():
  File "/usr/lib/python3/dist-packages/pymongo/cursor.py", line 1085, in _refresh
    self.__send_message(q)
  File "/usr/lib/python3/dist-packages/pymongo/cursor.py", line 924, in __send_message
    **kwargs)
  File "/usr/lib/python3/dist-packages/pymongo/mongo_client.py", line 1029, in _send_message_with_response
    exhaust)
  File "/usr/lib/python3/dist-packages/pymongo/mongo_client.py", line 1040, in _reset_on_error
    return func(*args, **kwargs)
  File "/usr/lib/python3/dist-packages/pymongo/server.py", line 85, in send_message_with_response
    with self.get_socket(all_credentials, exhaust) as sock_info:
  File "/usr/lib/python3.6/contextlib.py", line 81, in __enter__
    return next(self.gen)
  File "/usr/lib/python3/dist-packages/pymongo/server.py", line 138, in get_socket
    with self.pool.get_socket(all_credentials, checkout) as sock_info:
  File "/usr/lib/python3.6/contextlib.py", line 81, in __enter__
    return next(self.gen)
  File "/usr/lib/python3/dist-packages/pymongo/pool.py", line 920, in get_socket
    sock_info.check_auth(all_credentials)
  File "/usr/lib/python3/dist-packages/pymongo/pool.py", line 609, in check_auth
    auth.authenticate(credentials, self)
  File "/usr/lib/python3/dist-packages/pymongo/auth.py", line 486, in authenticate
    auth_func(credentials, sock_info)
  File "/usr/lib/python3/dist-packages/pymongo/auth.py", line 466, in _authenticate_default
    return _authenticate_scram_sha1(credentials, sock_info)
  File "/usr/lib/python3/dist-packages/pymongo/auth.py", line 209, in _authenticate_scram_sha1
    res = sock_info.command(source, cmd)
  File "/usr/lib/python3/dist-packages/pymongo/pool.py", line 517, in command
    collation=collation)
  File "/usr/lib/python3/dist-packages/pymongo/network.py", line 125, in command
    parse_write_concern_error=parse_write_concern_error)
  File "/usr/lib/python3/dist-packages/pymongo/helpers.py", line 145, in _check_command_response
    raise OperationFailure(msg % errmsg, code, response)
pymongo.errors.OperationFailure: Authentication failed.
me@ubuntu1:~/$

I'm certain the code is crashing on the last line of the script: for document in limited_cursor: print(document) If I comment out those last two lines, the script runs without error... but generates no output.

However, a careful reading of the traceback errors says the root problem is Authentication failed. So what does that mean? Is my URI incorrect?

I'm pretty sure the URI is correct. When I modify the script to print it to the console:

print(uri)

It comes out:

mongodb://me:[email protected]:27017/myDB?authSource=admin

That all looks right to me. The IP address and port are def correct, as is the database name. I've also created a me/password01 user within Mongo. From within the Mongo Shell:

> db.getUsers()
[
        {
                "_id" : "test.me",
                "userId" : UUID("5c3b4f1a-d05f-4015-9f6d-0b6cbbd7026c"),
                "user" : "me",
                "db" : "test",
                "roles" : [
                        {
                                "role" : "userAdminAnyDatabase",
                                "db" : "admin"
                        }
                ],
                "mechanisms" : [
                        "SCRAM-SHA-1",
                        "SCRAM-SHA-256"
                ]
        }
]
>

Any advice or tips is appreciated, thank you.

Alex Blex · Accepted Answer · 2022-06-24 22:02:50Z

1

userAdminAnyDatabase role does not allow to search data, it's to manage users.

You need readWriteAnyDatabase role

You created role in the test database but authenticating against admin database: ?authSource=admin. So either change you to ?authSource=test or (recommended) create the user in admin database. In mongo shell:

> use admin;
> db.createUser( { user: "me" ....})

edited Jun 24, 2022 at 22:02

answered Jun 24, 2022 at 20:18

Alex Blex

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5 Comments

Pete Over a year ago

Hmm. I've changed my user to "readWriteAnyDatabase", but am still getting the same error. When I (re)create the user, I'm using this command: db.createUser( { user: "me", pwd: "password01", roles:[{role: "readWriteAnyDatabase" , db:"admin"}]})

Alex Blex Over a year ago

ah, sorry, did notice you created the user in the test database. you are trying to authenticate on admin database - the authSource=admin thing. So either create a user there or change authSource in the url. And really, consider the course I mentioned the other day. It's free. It explains all of it much better than I do and in a more organised manner.

Pete Over a year ago

Yes, will do! And thank you for the recommendation on the course. I am taking the course you recommended, this post is actually me trying to apply the lessons of Chapters 1 and 2. They don't discuss authentication issues in the course materials, alas...

Alex Blex Over a year ago

I'd recommend to repeat this question on their discussion board. First of all it's curated and you may have an answer from the staff, and secondly they use it as a form of feedback to identify blind spots in the courses and improve them over time.

Pete Over a year ago

Ah, good idea. Will do. Thanks, Alex!

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