db.rake

# lib/tasks/db.rake
namespace :db do
  desc "Dumps the database to db/APP_NAME.dump"
  task :dump => :environment do
    cmd = nil
    epoch = Time.now.to_i
    with_config do |app, host, db, user|
      cmd = "pg_dump --verbose #{pg_login_config(host, user)} --clean --format=c #{db} > #{Rails.root}/db/#{app}-#{epoch}.dump"
    end
    puts cmd
    exec cmd
  end

  desc "List database dumps in db/ directory"
  task :list => :environment do
    cmd = nil
    cmd = "find #{Rails.root}/db -name \*.dump"
    puts cmd
    exec cmd
  end

  desc "Restores the database dump at db/APP_NAME-EPOCH.dump."
  task :restore, [:epoch] => :environment do |task, args|
    cmd = nil
    with_config do |app, host, db, user|
      cmd = "pg_restore --verbose #{pg_login_config(host, user)}  --clean --dbname #{db} #{Rails.root}/db/#{app}-#{args.epoch}.dump"
    end
    Rake::Task["db:drop"].invoke
    Rake::Task["db:create"].invoke
    puts cmd
    exec cmd
  end

  private
  def with_config
    app = Rails.application.class.parent_name.underscore
    host = ActiveRecord::Base.connection_config[:host]
    db = ActiveRecord::Base.connection_config[:database]
    username = ActiveRecord::Base.connection_config[:username]
    yield(app, host, db, username)
  end

  def pg_login_config(host, user)
    hoststring = host ? " --host #{host}" : ""
    userstring = user ? " --username #{user}" : ""
    "#{hoststring}#{userstring} --no-owner --no-acl "
  end
end

usage.sh

# dump the development db
rake db:dump

# dump the production db
RAILS_ENV=production rake db:dump

# List the database dumps
rake db:list
db/app-1414796108.dump
db/app-1414796244.dump

# Restore a specific database into development
rake db:restore:1414796244

# note: config/database.yml is used for database configuration,
#       but you will be prompted for the database user's password