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Tatsuhiko Miyagawa


Plack::Middleware::AccessLog - Logs requests like Apache's log format


  # in app.psgi
  use Plack::Builder;

  builder {
      enable "Plack::Middleware::AccessLog", format => "combined";


Plack::Middleware::AccessLog forwards the request to the given app and logs request and response details to the logger callback. The format can be specified using Apache-like format strings (or combined or common for the default formats). If none is specified combined is used.

This middleware uses calculable content-length by checking body type, and can not log the time taken to serve requests. It also logs the request before the response is actually sent to the client. Use Plack::Middleware::AccessLog::Timed if you want to log details after the response is transmitted (more like a real web server) to the client.

This middleware is enabled by default when you run plackup as a default development environment.


  enable "Plack::Middleware::AccessLog",
      format => '%h %l %u %t "%r" %>s %b "%{Referer}i" "%{User-agent}i"';

Takes a format string (or a preset template combined or custom) to specify the log format. This middleware implements a subset of Apache's LogFormat templates:

   %%    a percent sign
   %h    REMOTE_ADDR from the PSGI environment, or -
   %l    remote logname not implemented (currently always -)
   %u    REMOTE_USER from the PSGI environment, or -
   %t    [local timestamp, in default format]
   %r    REQUEST_METHOD, REQUEST_URI and SERVER_PROTOCOL from the PSGI environment
   %s    the HTTP status code of the response
   %b    content length
   %T    custom field for handling times in subclasses
   %D    custom field for handling sub-second times in subclasses
   %v    SERVER_NAME from the PSGI environment, or -
   %V    HTTP_HOST or SERVER_NAME from the PSGI environment, or -

Some of these format fields are only supported by middleware that subclasses AccessLog.

In addition, custom values can be referenced, using %{name}, with one of the mandatory modifier flags i, o or t:

   %{variable-name}i    HTTP_VARIABLE_NAME value from the PSGI environment
   %{header-name}o      header-name header
   %{time-format]t      localtime in the specified strftime format
  my $logger = Log::Dispatch->new(...);
  enable "Plack::Middleware::AccessLog",
      logger => sub { $logger->log(level => 'debug', message => @_) };

Sets a callback to print log message to. It prints to psgi.errors output stream by default.


http://httpd.apache.org/docs/2.2/mod/mod_log_config.html Rack::CustomLogger