Add Hanami 1.x instrumentation

[TonyCTHsu]

Setup Guide

Install

in Gemfile

gem 'ddtrace', require: 'ddtrace/auto_instrument'

Configuration

in config/initializers/datadog.rb

Datadog.configure do |c|
  # Do your custom configuration
end

---

What does this Hanami instrumentation provide?

Instrument Hanami 1.x, internally activating rack to instrument rack, which is usually the root span and could handle distributing tracing.

3 spans are generated by a Hanami instrumentation, which are routing, action, render.

• routing starts recording from endpoint lookup til the response is returned
• action covers the time for an action execution, including callbacks such as before and after
• render describes the duration when an output is provided(from action or rack middleware) to be rendered.

#979

The example flamegraph pattern looks like below

[ivoanjo]

Since this PR is already big as-is, here's a suggestion: consider doing a separate PR to just add Hanami as a test app (even if it doesn't work until we actually add the instrumentation).

That way we can focus more on the actual changes and how instrumentation looks vs getting lost in the noise of bootstrapping an example Hanami application. 😄

[codecov-commenter]

Codecov Report

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[marcotc]

🚢 !