Hey Afanasiy,
This forum is meant for more high level discussion of the platform and services, while your post represents a specific technical issue you've encountered when trying to follow a tutorial. You should post a question to
Stack Overflow with more detailed information on what you have attempted to do to resolve the issue. As you might be able to tell from the error message, it's possible that the mongo server is not listening on port 27017. When you create that post on Stack Overflow, feel free to post the link here and I'll be glad to assist. There is a much larger community on Stack which will assist you.
Cheers,
Nick
Cloud Platform Community Support