Hello, I can not connect to AWS DocumentDB using the new rust mongo driver.

I fully understand that MongoDB does not make it a priority to be interoperable with AWS DocumentDB and that they are competitors, however I do not get to decide on the database backend we utilize and I have been tasked with working with AWS DocumentDB from rust.

I am able to connect to DocumentDB over an SSH tunnel using the Python driver without issue.

For example, in Python I have:

uri: str = mongodb://redacted:redacted@localhost:27017/?tls=true&tlsCAFile=/redacted/rds-ca-2019-root.pem&tlsInsecure=true
client: pymongo.MongoClient = pymongo.MongoClient(uri)
for db_name in client.list_database_names():
    print(db_name)

And this works fine to display our databases.

However, in Rust, I have:

let uri: String = "mongodb://redacted:redacted@localhost:27017/?tls=true&tlsCAFile=/redacted/rds-ca-2019-root.pem&tlsInsecure=true".to_string();
let client = Client::with_uri_str(&uri).unwrap();
for db in client.list_database_names(None).unwrap() {
    println!("{}", db);
}

 This eventually fails with the error:

{{thread 'main' panicked at 'called `Result::unwrap()` on an `Err` value: Error { kind: ServerSelectionError

}', src/main.rs:31:15}}

I've done a little big of digging, but haven't gotten very far. At a minimum, I can observe that select_server is not able to find any suitable servers. It appears that all servers have a description of "Unknown".

I am happy to submit a PR and do some digging if anyone has any ideas as to the cause of this issue and where I might look.

Your time is greatly appreciated and I look forward to working with you to resolve these issues. Please let me know if there is any other information I can provide. I have access to the rust mongo source and can debug from within it if needed.