Dogcatcher is a tool to track exceptions in Ruby applications and send them to Datadog

Add this line to your application's Gemfile:

gem 'dogcatcher'

And then execute:

$ bundle

Or install it yourself as:

$ gem install dogcatcher

This is an example that you can use anywhere within your Ruby project. By default the exception will be sent to statsd running on the local host.

require 'dogcatcher'

begin
  fail ArgumentError, 'Example error'
rescue ArgumentError => exception
  Dogcatcher.notify(exception)
  raise exception
end

When dogcatcher has been required in a Rakefile, the all exceptions raised in any Rake task will automatically be collected.

require 'dogcatcher'

task :example_task do
  fail ArgumentError, 'Example error'
end

By default Dogcatcher will send metric and event data to statsd running on the local host. By specifying a Datadog API key, Dogcatcher will switch to sending events to the Datadog API instead.

Dogcatcher.configure do |c|
  c.api_key = '<datadog API key goes here>'
end

Since the default approach is to send data to one or the other, options are available to explicitly control where the data is sent.

Dogcatcher.configure do |c|
  c.use_dogapi = true
  c.use_statsd = true
end

By default Dogcatcher will send both metrics and events, but these can be disabled individually.

Dogcatcher.configure do |c|
  c.send_metric = false
  c.send_event = false
end

Metrics will be sent with a default name of dogcatcher.errors.count, this can be customized by setting the metric_name configurable.

Dogcatcher.configure do |c|
  c.metric_name = 'my_app.errors.count'
end

The host and port that statsd data is sent to can be configured like so.

Dogcatcher.configure do |c|
  c.statsd_host = '127.0.0.1'
  c.statsd_port = 8125
end

An optional program name can be specified to help distinguish between multiple applications. This will appear in the event title and as a tag on the metric.

Dogcatcher.configure do |c|
  c.program = 'Example program'
end

By default, Dogcatcher will add tags for each gem and its version found in the backtrace. This can be disabled if required.

Dogcatcher.configure do |c|
  c.gem_tags = false
end

The backtrace can be cleaned by adding filters or silencers. The filters shown below were used to generate the screenshot shown above.

Dogcatcher.configure do |c|
  c.add_filter { |line| line.gsub(Dir.pwd, '.') }
  c.add_filter { |line| line.gsub(%r{^.*/gem/ruby/[0-9.]+/gems/([A-Za-z0-9\-_]+)-([0-9.]+(\.[a-z]+(\.[0-9]+)?)?)/}, '\1 (\2) ') }
  c.add_filter { |line| line.gsub(%r{.*/gem/ruby/[0-9.]+(/bin/)}, '<gem path>\1') }
  c.add_filter { |line| line.gsub(%r{.*(/lib/ruby/[0-9.]+)}, '<interpreter path>\1') }
  c.add_silencer { |line| false }
end

Custom tags can be sent with exception data by adding them to the config.

Dogcatcher.configure do |c|
  c.custom_tags = ['key1:value1']
  c.custom_tags << 'key2:value2'

  # Proc will be evaluated when exception is caught
  c.custom_tags << proc { 'key3:value3' }
end

Bug reports and pull requests are welcome on GitHub at https://github.com/zl4bv/dogcatcher.

The gem is available as open source under the terms of the MIT License.