ruby DATABASE_URL parse

database.yml

<%
require 'cgi'
require 'uri'

begin
  uri = URI.parse(ENV["DATABASE_URL"])
rescue URI::InvalidURIError
  raise "Invalid DATABASE_URL"
end

env = ENV["RAILS_ENV"] || ENV["RACK_ENV"]

raise "No RACK_ENV or RAILS_ENV found" unless env


def attribute(name, value, force_string = false)
  if value
    value_string =
      if force_string
        '"' + value + '"'
      else
        value
      end
    "#{name}: #{value_string}"
  else
    ""
  end
end

database = "#{(uri.path || "").split("/")[1]}_#{env}"
username = uri.user
password = uri.password
host     = uri.host
port     = uri.port
params   = CGI.parse(uri.query || "")

params["encoding"] = ["utf8"] unless params["encoding"].present?
params["pool"    ] = [5]      unless params["pool"    ].present?

adapter = case uri.scheme.to_s
          when "postgres" then "postgresql"
          when "mysql"    then "mysql2"
          else uri.scheme.to_s
          end
%>

<%= env %>:
  <%= attribute "adapter",  adapter %>
  <%= attribute "database", database %>
  <%= attribute "username", username %>
  <%= attribute "password", password, true %>
  <%= attribute "host",     host %>
  <%= attribute "port",     port %>

<% params.each do |key, value| %>
  <%= key %>: <%= value.first %>
<% end %>

Useful, cheers!

https://gist.github.com/gullitmiranda/62082f2e47c364ef9617#file-database-yml-L6 allows only URL safe chars reducing overall password complexity. If you generate random password, make sure to only include URL safe chars.