Connecting to Atlas MongoDb using pymongo - ServerSelectionTimeoutError

Question

I'm having trouble connecting to a db I set up in Atlas MongoDB. I have already read multiple other questions but no answer made my connection work. I want to point out that I am trying to access it behind a company's proxy (if that has anything to do with it). My code is this and fails only on the last line where I try to count the documents:

from pymongo import MongoClient


client = MongoClient(
    "mongodb+srv://name:pass@iliastrialcluster-1tl2y.azure.mongodb.net/test?retryWrites=true&w=majority&ssl=true&ssl_cert_reqs=CERT_NONE"
)
db = client.get_database('sample_airbnb')
print(db)
listings_and_reviews = db.listingAndReviews
print(listings_and_reviews)
listings_and_reviews.count_documents({})

The error I get is:

Traceback (most recent call last):
  File "C:~/mongo_connection1.py", line 11, in <module>
    listings_and_reviews.count_documents({})
  File "C:~\lib\site-packages\pymongo\collection.py", line 1721, in count_documents
    _cmd, self._read_preference_for(session), session)
  File "C:~\lib\site-packages\pymongo\mongo_client.py", line 1454, in _retryable_read
    read_pref, session, address=address)
  File "C:~\lib\site-packages\pymongo\mongo_client.py", line 1253, in _select_server
    server = topology.select_server(server_selector)
  File "C:~\lib\site-packages\pymongo\topology.py", line 235, in select_server
    address))
  File "C:~\lib\site-packages\pymongo\topology.py", line 193, in select_servers
    selector, server_timeout, address)
  File "C:~\lib\site-packages\pymongo\topology.py", line 209, in _select_servers_loop
    self._error_message(selector))
pymongo.errors.ServerSelectionTimeoutError: iliastrialcluster-shard-00-00-1tl2y.azure.mongodb.net:27017: timed out,iliastrialcluster-shard-00-02-1tl2y.azure.mongodb.net:27017: timed out,iliastrialcluster-shard-00-01-1tl2y.azure.mongodb.net:27017: timed out

Answer 1

ServerSelectionTimeout error is the client's way of telling you you can't connect to the server. The primary cause of these errors when using MongoDB Atlas is the failure to enable access for the IP address of the node the client is running on.

To verify try connecting using the MongoDB shell mongo using the same connection string. if you get a connection failed then you know it's not a Python problem. Your client code looks OK BTW so I am pretty sure this is what it is.

The connection to the server is lazily evaluated so we don't try to initiate a connection until you make an actual request. In this case the count_documents call. This is why this is the call that generates the error.

Answer 2

@JoeDrumgoole Thanks for your answer. The problem was the proxy after all, after deactivating it the connection works fine. Good to know that the connection to the server is lazily evaluated.