Build Status

Metrics Reporter

A minimalist Application Performance Monitoring (APM) library for Ruby on Rails.

The middleware generates a CSV file with the followinfg fields (no header):

  • Request Time: the timestamp when the request enters the middleware
  • Response Time: the timestamp when the response leaves the middleware
  • Elapsed Time: the time betwen request and response
  • Path: the URI of the request
  • Params: a semi-colon delimited list of GET parameters
  • Thread ID: the thread ID of the current request
  • Process ID: the process ID of the current request
  • MD5: the hash value of the response body

The location and name of the file are configurable by the user.

Optionally: Does MD5 calculation in Rust if native extention is built.

Getting Started

Yard Docs


Install from ruby gems

bundle add rack_middleware_metrics

Non-rails Setup

See example for setup with rack directly.

class RackApp
  def _env
    [200, { some_header: 'a value' }, ['Hi!']]

app = do
    use(RackMiddlewareMetrics::Reporter, logpath: 'some_metrics_filepath.csv')

handler = Rack::Handler::Thin, Port: 8082)

Rails setup.

The middleware is automatically registered with Rails. But to configure the logpath add:

    config.rack_middleware_metrics.logpath = Rails.root / 'some_metrics_filepath.csv'

to config/environments/*.rb

Example Output from Redmine Rails Project

Start End Duration(S) URI Params Thread PID MD5
2020-10-27 13:32:46 -0700 2020-10-27 13:32:47 -0700 0.698014072 http://localhost:3000/ 55890640 18581 1724d0f493f9ed2e191d9aeb49df0f4c
2020-10-27 13:33:07 -0700 2020-10-27 13:33:07 -0700 0.02697148 http://localhost:3000/ 70368509891620 18581 80eabd1e0373408b0a40b08b0eec6c3f
2020-10-28 09:40:16 -0700 2020-10-28 09:40:16 -0700 0.717337538 http://localhost:3000/ 55777940 16173 89ab1d3fcc2d9dcdef4a50d79e9dcaff
2020-10-28 09:40:41 -0700 2020-10-28 09:40:41 -0700 0.103701273 http://localhost:3000/projects 55777940 16173 d2ddd9efc455f83cb24060e6593d6c6c
2020-10-28 09:41:44 -0700 2020-10-28 09:41:44 -0700 0.051811471 http://localhost:3000/projects blah=funk 70368510966560 16173 eb2dacf2043e866a9e8925e53d471e6f
2020-10-28 09:44:02 -0700 2020-10-28 09:44:03 -0700 0.831327261 http://localhost:3000/projects blah=funk;blah2=2funky 55777780 17355 40895fa7af099cae3f48b27f149beb30


CI/CD is managed via Travis CI.

Build and Test Manually

Build via:

bundler install --path=vendor

Run spec via:


Build the Rust Extension

Install Rust if not present.

curl -sSf | sh -s -- -y

source $HOME/.cargo/env

Build extension.

./bin/rake build

PRs and Testing

A pull request will trigger builds for each of the Ruby versions supported against Ubuntu Xenial.


Releases from Travis are triggered whenever a commit to the main branch is tagged. Spec tests must pass for release to occur.