Ruby on Rails web backend expert engineer

We are looking for a Ruby on Rails web backend engineer to handle implementing server-side Ruby on Rails program of our web service.

Our service is a music-related online marketplace for indie artists and their fans now in its 5th year. We have built the entire product in-house up until today and now are looking to ramp up development starting this Spring.

Things you'll be expected to do:
- To implement website interface improvements
- New feature development
- Streamline and improve the functionality of current services
- Continuous maintenance (backend)
- Dashboard maintenance and operation improvement support for Operation Team
- Construction and maintenance of server infrastructure
- Refactoring existing legacy RoR / JS codes
- Implement insufficient test codes

Requirements:
- Experience of Ruby on rails development (over 5 years)
- Experience of general JavaScript development (jQuery etc.) (over 3 years)
- Experience of RSpec test case writing.
- Experience with using amazon web services.
- Basic of API design, using Web API
- Skill of using Docker
- Skill of build Docker development environment (better)
- Basic of Linux / Unix
- Basic of HTML/CSS coding skills