databases.yml

default: &default
  encoding: utf8
  adapter: mysql2
  port: <%= ENV['MYGEM_DATABASE_PORT'] %>
  host: <%= ENV['MYGEM_DATABASE_HOST'] %>
  username: <%= ENV['MYGEM_DATABASE_USERNAME'] %>
  password: <%= ENV['MYGEM_DATABASE_PASSWORD'] %>
  pool: <%= ENV.fetch("RAILS_MAX_THREADS") { 5 } %>

development:
  mygem_db_key_1:
    <<: *default
    database: mygem_database_1
  mygem_db_key_2:
    <<: *default
    database: mygem_database_2