在Sinatra中使用Rack :: CommonLogger [英] Use Rack::CommonLogger in Sinatra

问题描述

我有一个用Sinatra编写的小型Web服务器.我希望能够将消息记录到日志文件中.我已经阅读了 http://www.sinatrarb.com/api/index.html和www.sinatrarb.com/intro.html，我看到Rack有一个叫做Rack :: CommonLogger的东西，但是我找不到任何有关如何访问和用来记录消息的示例.我的应用程序很简单，因此我将其编写为顶级DSL，但是如果需要，我可以切换到SinatraBase对其进行子类化.

I have a small web-server that I wrote with Sinatra. I want to be able to log messages to a log file. I've read through http://www.sinatrarb.com/api/index.html and www.sinatrarb.com/intro.html, and I see that Rack has something called Rack::CommonLogger, but I can't find any examples of how it can be accessed and used to log messages. My app is simple so I wrote it as a top-level DSL, but I can switch to subclassing it from SinatraBase if that's part of what's required.

推荐答案

Rack::CommonLogger不会为您的主应用提供记录器，它只会像Apache一样记录请求.

Rack::CommonLogger won't provide a logger to your main app, it will just logs the request like Apache would do.

亲自检查代码: https://github .com/rack/rack/blob/master/lib/rack/common_logger.rb

所有Rack应用程序都具有通过HTTP Request env调用的调用方法，如果您检查此中间件的调用方法，则会发生这种情况:

All Rack apps have the call method that get's invoked with the HTTP Request env, if you check the call method of this middleware this is what happens:

def call(env)
  began_at = Time.now
  status, header, body = @app.call(env)
  header = Utils::HeaderHash.new(header)
  log(env, status, header, began_at)
  [status, header, body]
end

在这种情况下，@app是主应用程序，中间件只是在注册请求开始的时间，然后将您的中间件分类为[status，header，body]三元组，然后调用私有日志方法使用这些参数，返回与您的应用最初返回的相同的三元组.

The @app in this case is the main app, the middleware is just registering the time the request began at, then it class your middleware getting the [status, header, body] triple, and then invoke a private log method with those parameters, returning the same triple that your app returned in the first place.

logger方法类似于:

def log(env, status, header, began_at)
  now = Time.now
  length = extract_content_length(header)

  logger = @logger || env['rack.errors']
  logger.write FORMAT % [
    env['HTTP_X_FORWARDED_FOR'] || env["REMOTE_ADDR"] || "-",
    env["REMOTE_USER"] || "-",
    now.strftime("%d/%b/%Y %H:%M:%S"),
    env["REQUEST_METHOD"],
    env["PATH_INFO"],
    env["QUERY_STRING"].empty? ? "" : "?"+env["QUERY_STRING"],
    env["HTTP_VERSION"],
    status.to_s[0..3],
    length,
    now - began_at ]
end

如您所知，log方法只是从请求env中获取一些信息，并登录到在构造函数调用中指定的记录器，如果没有记录器实例，则转到rack.errors记录器(默认情况下似乎有一个记录器)

As you can tell, the log method just grabs some info from the request env, and logs in on a logger that is specified on the constructor call, if there is no logger instance then it goes to the rack.errors logger (it seems there is one by default)

使用方式(在您的config.ru中):

The way to use it (in your config.ru):

logger = Logger.new('log/app.log')

use Rack::CommonLogger, logger
run YourApp

如果要在所有应用程序中使用通用记录器，则可以创建一个简单的记录器中间件:

If you want to have a common logger in all your app, you could create a simple logger middleware:

class MyLoggerMiddleware

  def initialize(app, logger)
    @app, @logger = app, logger
  end

  def call(env)
    env['mylogger'] = @logger
    @app.call(env)
  end

end

要使用它，请在您的config.ru上:

To use it, on your config.ru:

logger = Logger.new('log/app.log')
use Rack::CommonLogger, logger
use MyLoggerMiddleware, logger
run MyApp

希望这会有所帮助.

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