Rails Rake task for easy Postgres database dumping and cleanup of old dumps

db.rake

# https://gist.github.com/amit/45e750edde94b70431f5d42caadee423
namespace :db do
  DEFAULT_BACKUP_DIR = "#{Rails.root}/tmp/backups"
  BACKUP_DIR = ENV['DB_BACKUP_DIR'].presence || DEFAULT_BACKUP_DIR
  KEEP = ENV['DB_BACKUP_KEEP'].present? ? ENV['DB_BACKUP_KEEP'].to_i : 7

  desc "Dumps the database to backups"
  task dump: :environment do
    cmd = nil
    with_config do |_app, host, db, user, passw, port|
      file_name = "#{Time.now.strftime('%Y%m%d%H%M%S')}_#{db}.sql.gz"
      opts = "-d #{db}"
      if host.present?
        opts += " -h #{host}"
      end
      if user.present?
        opts += " -U #{user}"
      end
      if port.present?
        opts += " -p #{port}"
      end
      cmd = "pg_dump #{opts} | gzip > #{backup_directory}/#{file_name}"
      if passw.present?
        cmd = "PGPASSWORD=#{passw} #{cmd}"
      end
    end
    if Rake.application.top_level_tasks == ['db:dump']
      puts cmd
      exec cmd
    else
      sh cmd
    end
  end

  desc "Cleanup the database backups, keeping #{KEEP} most recent"
  task cleanup: :environment do
    files = Dir.glob("#{backup_directory}/*.{dump,sql,tar,dir}.gz")
    files.sort_by! { |f| -File.ctime(f).to_i }
    to_cleanup = files.drop(KEEP)
    if to_cleanup.any?
      puts "rm #{to_cleanup.map { |i| File.basename(i) }.join(' ')}"
      FileUtils.rm(to_cleanup)
    end
  end

  task :dump_and_cleanup => [:dump, :cleanup]

  private

  def backup_directory
    FileUtils.mkdir_p(BACKUP_DIR)
    BACKUP_DIR
  end

  def with_config
    yield Rails.application.class.module_parent_name.underscore,
      ActiveRecord::Base.connection_db_config.host,
      ActiveRecord::Base.connection_db_config.database,
      ActiveRecord::Base.connection_db_config.configuration_hash[:username],
      ActiveRecord::Base.connection_db_config.configuration_hash[:password],
      ActiveRecord::Base.connection_db_config.configuration_hash[:port] || 5432
  end
end