Taps allow you to migrate your data between different databases, unfortunately it have a well know bug using pull with recent version of rack. That's a simple workaround:
$ mkdir taps && cd taps && nano Gemfile
source 'https://rubygems.org' gem 'rack','1.0.1' gem 'taps' gem 'sqlite3' gem 'pg' gem 'mysql2'
$ bundle
$ bundle exec taps server postgres://user:pass@host:port/origin_db_name?encoding=UTF8 db db
$ taps pull mysql://user:pass@host:port/destination_db_name?encoding=UTF8 http://db:db@localhost:5000