Script to start redis using command line options, rather than a config file

redis

#!/usr/bin/env ruby

#
# Run redis-server with settings taken from the command line.
#
# Source: https://gist.github.com/929513
#

require 'optparse'
require 'fileutils'
require 'tempfile'
require 'erb'

class App
  RC_DIR = File.expand_path('~/.redis')

  def initialize(args)
    @port = 6379
    @log_level = 'debug'
    @db_path ||= "#{RC_DIR}/PORT.rdb"
    @log_path ||= "#{RC_DIR}/PORT.log"
    @pid_path ||= "#{RC_DIR}/PORT.pid"
    parser = OptionParser.new do |parser|
      parser.banner = "Usage: #$0 [options] start|stop|run"
      parser.on '-p', '--port=PORT', "Port to listen on (default: #{port})" do |port|
        @port = port
      end
      parser.on '-l', '--log-path=PATH', "Path of log file (default: #{@log_path})" do |log_path|
        @log_path = log_path
      end
      parser.on '-P', '--pid-path=PATH', "Path of pid file (default: #{@pid_path})" do |pid_path|
        @pid_path = pid_path
      end
      parser.on '-d', '--db-path=PATH', "Path of the database file (default: #{@db_path})" do |db_path|
        @db_path = db_path == '-' ? '-' : File.expand_path(db_path)
      end
      parser.on '-L', '--log-level=LEVEL', "Log level [debug|verbose|notice|warning] (default: #{log_level})" do |log_level|
        @log_level = log_level
      end
    end

    @configs, args = args.partition { |arg| arg =~ /=/ }

    parser.parse!(args)
    @db_path.sub!(/PORT/, @port.to_s)
    @log_path.sub!(/PORT/, @port.to_s)
    @pid_path.sub!(/PORT/, @port.to_s)

    args.size == 1 or
      abort parser.banner
    @command = args.first
  end

  attr_reader :command, :port, :log_path, :pid_path, :db_path, :log_level, :configs

  def run
    FileUtils.mkdir_p RC_DIR
    clean_stale_pid_file
    case command
    when 'start', 'run'
      !running? or
        abort "Already running."
      with_redis_config do |path|
        run_redis(path)
      end
    when 'stop'
      running? or
        abort "Not running."
      Process.kill 'INT', File.read(pid_path).to_i
      File.delete(pid_path)
    end
  end

  def clean_stale_pid_file
    if !File.exist?(pid_path)
      @running = false
    else
      pid = File.read(pid_path).strip
      `ps -p #{pid}`
      @running = $?.success?
      if !@running
        STDERR.puts "Deleting stale PID file: #{pid_path}"
        File.delete(pid_path)
      end
    end
  end

  def running?
    @running
  end

  def with_redis_config
    file = nil
    begin
      Tempfile.open("redis-conf:#{port}") do |f|
        file = f
        f.print interpret_config
      end
      yield file.path if file
    ensure
      FileUtils.rm_f file.path
    end
  end

  def interpret_config
    ERB.new(DATA.read).result(binding)
  end

  def run_redis(config_path)
    # Spawn a child process, as the tempfile will be deleted when we exit.
    system 'redis-server', config_path or
      abort "Redis failed with status #{$?.exitstatus}"
  end
end

App.new(ARGV).run

__END__
port <%= port %>
pidfile <%= pid_path %>
<% if log_path %>logfile <%= log_path %><% end %>
loglevel <%= log_level %>
<% unless db_path == '-' %>
dir <%= File.dirname(db_path) %>
dbfilename <%= File.basename(db_path) %>
save 60 1
<% end %>
<%= configs.map { |c| c.sub(/\s*=\s*/, ' ') }.join("\n") %>
daemonize <%= command == 'run' ? 'no' : 'yes' %>
timeout 0