DRY Database Config for Rails

database.yml

default: &default
  adapter: postgresql
  encoding: unicode
  # For details on connection pooling, see Rails configuration guide
  # http://guides.rubyonrails.org/configuring.html#database-pooling
  pool:     <%= ENV.fetch("RAILS_MAX_THREADS") { 5 } %>
  username: <%= ENV.fetch("DB_USER") { "postgres" } %>
  password: <%= ENV.fetch("DB_PASSWORD") { "postgres" } %>
  host:     <%= ENV.fetch("DB_HOST") { "localhost" } %>
  port:     <%= ENV.fetch("DB_PORT") { 5432 } %>