README.md

Heroku Postgresql credentials retriever

WARNING: be careful what you do with this.

Installation

• Create a scripts directory in your Rails app root (if it doesn't already exist) and put the script inside

Usage

$ ruby scripts/use_heroku_db.rb

Run the script with to copy credentials from Heroku DB to your "database.yml".

Your previous "database.yml" will be backed up to "config/database.yml.orig". Run the script again to automatically restore your original "database.yml".

Advanced

You can pass an optional remote name if you have multiple Heroku apps. E.g. if you've got "staging" and "production" remotes, you can get staging's DB credentials with:

$ ruby scripts/use_heroku_db.rb staging

use_heroku_db.rb

#!/usr/bin/env ruby

require 'uri'
require 'pry'
require 'yaml'
require 'pathname'

class HerokuDbCredentials
  attr_accessor :connection_uri

  def initialize(environment=nil)
    command_string = "heroku pg:credentials DATABASE"
    if environment
      command_string << " --remote #{environment}"
    end

    connection_data = `#{command_string}`
    connection_url_string = connection_data.split.last
    self.connection_uri = URI.parse(connection_url_string)
  end

  def to_hash
    {
      'development' => {
        'adapter' => 'postgresql',
        'encoding' => 'unicode',
        'pool' => 5,
        'database' => connection_uri.path.gsub(/^\//, ''),
        'username' => connection_uri.user,
        'password' => connection_uri.password,
        'host' => connection_uri.host,
        'port' => connection_uri.port,
      }
    }
  end

  def to_yaml
    to_hash.to_yaml
  end
end

class RailsRoot < Pathname
  def self.new
    super(File.expand_path(__FILE__)).join('../..')
  end
end

class ConfigManager
  attr_accessor :rails_root, :database_yaml, :database_yaml_backup

  def initialize
    self.rails_root = RailsRoot.new
    self.database_yaml = rails_root.join('config', 'database.yml')
    self.database_yaml_backup = rails_root.join('config', 'database.yml.orig')
  end

  def should_restore?
    return false unless File.exist?(database_yaml_backup)
    !FileUtils.compare_file(database_yaml, database_yaml_backup)
  end

  def backup_database_yaml
    puts "Backing up database.yml"
    FileUtils.cp(database_yaml, database_yaml_backup)
  end

  def restore_database_yaml
    return false unless should_restore?

    puts "Restoring database.yml from backup"
    FileUtils.move(database_yaml_backup, database_yaml)
    true
  end

  def rewrite_database_yaml(config)
    puts "Writing Heroku production config to database.yml"
    File.open(database_yaml, 'w') do |f|
      f.puts config.to_yaml
    end
  end
end

def main
  env = ARGV.shift

  cm = ConfigManager.new
  return if cm.restore_database_yaml

  cm.backup_database_yaml

  credentials = HerokuDbCredentials.new(env)
  cm.rewrite_database_yaml(credentials)

  puts "Run this script again to restore database.yml from config to connect to the local db"
end

main