Using proper virtualenv and flake8 config with Flycheck

Question

How can I use configured virtualenv and flake8 settings file (setup.cfg in root of project), for flycheck in emacs?

Answer 1

I spent some time to find right solution and decided to implement my own:

flycheck-local-flake8

This is plugin for flycheck-flake8 checker, simply uses flake8 from required virtualenv and setup.cfg from root of the python project.