Plack::Middleware::StatsPerRequest - Measure HTTP stats on each request


version 0.902


  use Plack::Builder;
  use Measure::Everything::Adapter;
  Measure::Everything::Adapter->set('InfluxDB::File', {
      file => '/tmp/yourapp.stats',

  builder {
      enable "Plack::Middleware::StatsPerRequest",
          app_name => 'YourApp',

  # curl http://localhost:3000/some/path
  # cat /tmp/yourapp.stats
    http_request,app=YourApp,method=GET,path=/some/path,status=400 hit=1i,request_time=0.02476 1519658691411352000


Plack::Middleware::StatsPerRequest lets you collect stats about all your HTTP requests via Measure::Everything. Plack::Middleware::StatsPerRequest calculates the duration of a requests and collects some additonal data like request path, HTTP method and response status.

You can then use this data to plot some nice graps, find bottlenecks or set up alerts; or do anything else your stats toolkit supports.


  enable "Plack::Middleware::StatsPerRequest",
      metric_name   => 'http',
      app_name      => 'YourApp',
      path_cleanups => [ \&your_custom_cleanup, \&another_cleanup ],
      add_headers   => [ qw( Accept-Language X-Requested-With )],
      long_request  => 3


The name of the metric generated. Defaults to http_request.


The name of your application. Defaults to unknown.

app_name will be added to each metric as a tag.


A list of functions to be called to transform / cleanup the request path. Defaults to [ 'replace_idish' ].

Set to an empty list to do no path cleanups. This is not recommended, unless your statistic tool can normalize paths which might include a lot of distinct ids etc; or your app does not include ids in its URLs (maybe they are all passed via query params?)

See replace_idish for more info on the default path cleanup handler.


A list of HTTP header fields. Default to [ ] (empty list).

If you use add_headers, all HTTP headers matching the ones provided will be added as a tag, with the respective header values as the tag values.

   enable "Plack::Middleware::StatsPerRequest",
            add_headers => [ 'Accept-Language' ];
   # header_accept-language=Accept-Language

If a header is not sent by a client, a value of not_set will be reported.


A list of HTTP header fields. Default to [ ] (empty list).

Checks if a HTTP header is set, and adds a tag containing 1 or 0. This makes sense if you just what to count if a header was sent, but don't care about it's content (eg a bearer token):

   enable "Plack::Middleware::StatsPerRequest",
            has_headers => [ 'Authorization' ];
   # has_header_authorization=1


Requests taking longer than long_request seconds will be logged as a warning. Defaults to 5 seconds.

Set to 0 to turn off.

   enable "Plack::Middleware::StatsPerRequest",
            long_request => 10;
   # curl http://localhost/very/slow/endpoint
   # cat /log/warnings
     Long request, took 23.042: GET /very/slow/endpoint



  my $clean = Plack::Middleware::StatsPerRequest::replace_idish( $dirty );

Takes a URI path and replaces things that look like ids with fixed strings, so you can calc proper stats on the generic paths.

This is the default path_cleanups action, so unless you specify your own, or explicitly set path_cleanups to an empty array, the following transformations will be done on the path:

  • All path fragments looking like a SHA1 checksum are replaced by :sha1.

  • All path fragments looking like a UUID are replaced by :uuid.

  • Any part of the path consisting of 6 or more digits is replaced by :int.

  • A llpath fragments consisting solely of digits are also replaced by :int.

  • All path fragments looking like hex are replaced by :hex.

  • All path fragments longer than 55 characters are replaced by :long.

  • A chain of path fragments looking like hex-code is replaced by :hexpath.

  • All path fragments looking like an email message id (as generated by one of our tools) are replaced by :msgid.

  • All path fragments looking like 300x200 are replaced by :imgdim. (Of course this happens for all formats, not just 300 and 200).

For details, please inspect the source code and t/20_replace_idish.t.

These transformations proved useful in the two years we used Plack::Middleware::StatsPerRequest in house. If you have any additions or change requests, just tell us!



Thanks to


Thomas Klausner <>


This software is copyright (c) 2018 - 2021 by Thomas Klausner.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.