Rack::Logstash is a Rack-compliant middleware designed to satisfy all your needs when it comes to logging Rack requests and responses to Logstash. In particular, it:

• Sends a log entry for each successful request/response, in a format compatible with grok's default APACHECOMBINEDLOG format (allowing easy integration with anything that understands those log entries);

• Catches all unhandled exceptions and logs them;

• Logs request headers for 4xx responses, and request and response headers for 5xx responses;

• Sends the log entries directly to a logstash server, using JSON-over-TCP.

If that sounds like the sort of thing you'd like to have, then this is the middleware for you.

Installation

It's a gem:

gem install rack-logstash

There's also the wonders of the Gemfile:

gem 'rack-logstash'

If you're the sturdy type that likes to run from git:

rake install

Or, if you've eschewed the convenience of Rubygems entirely, then you presumably know what to do already.

Usage

It is very simple to configure your Rack middleware stack to include Rack::Logstash:

require 'rack/logstash'

use Rack::Logstash, "tcp://192.0.2.42:5151"

run MyApp

That's all there is to it. The middleware takes one mandatory argument, a tcp:// URL pointing to the logstash TCP input address and port.

Tagging log entries

If you'd like to tag the log entries that Rack::Logstash emits, you can do so using the tags option, like this:

use Rack::Logstash, "tcp://192.0.2.42:5151",
                    :tags => ["foo", "bar", "baz"]

Any array of strings will be accepted.

Logstash server config

You must have a tcp input plugin configured in your logstash server, otherwise nothing is going to end well for you. Specifically, your config should look something very much like this:

input {
  tcp {
    codec => "json_lines",
    port  => 5151
  }
}

You can, of course, have other input plugins as well, and you can change the port to whatever you like (as long as you adjust the port in the URL you pass to Rack::Logstash). The codec, however, must be json_lines.

Contributing

Bug reports should be sent to the Github issue tracker, or e-mailed. Patches can be sent as a Github pull request, or e-mailed.

Licence

Unless otherwise stated, everything in this repo is covered by the following copyright notice:

Copyright (C) 2015  Matt Palmer <[email protected]>

This program is free software: you can redistribute it and/or modify it
under the terms of the GNU General Public License version 3, as
published by the Free Software Foundation.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.