3 answers
Richie’s Answer
If you use Google's App Engine to build you application, you can use the App Engine APIs to handle logins.'
Here is an example in Python.
Hope this helps.
...richie
John’s Answer
The first question I have to ask is: "how sensitive is the data you're protecting"? Speaking as a Cyber Security professional, the potential damage from someone breaking in should determine how hard you have to work on your login code.
That said, coding login is rarely trivial. The easiest way if you have ftp/ssh access to the folders you want to protect is to use an .htaccess file. Check out http://www.htaccess-guide.com/
Another option is to use some pre-built code that implements OAuth. https://oauth.net/articles/authentication/
There are still other options, like Google's App Engine, as mentioned in the other answer. A web search should help you find some.
Hope this helps.