How we solved the problem of documenting and running tests

My experience in QA and communication with QA engineers in other companies demonstrated that everybody faces the same problems.  In particular, how to test a big number of microservices? How to run tests on different environments? How to satisfy requests from developers and managers to run tests in different combinations? And where to store test descriptions and documentation? 

I have decided to share my experience and provide solutions for the problems we faced. Also, I'd like to share advices of what should be avoided when testing.