Provide skylight integration

[mostlyobvious]

We already have instrumented most of the interesting internals via https://railseventstore.org/docs/instrumentation/ which for rails_event_store gem works with ActiveSupport::Notifications.

It may be possible that no further work in RES (nor in additional library) is needed. Instead we may want to document the integration process.

https://www.skylight.io/support/getting-more-from-skylight#probes

[mostlyobvious]

It seems that what we need is called Normalizers:

• https://github.com/hmcfletch/fast_jsonapi/blob/7f030a2f8b8c7136bc10a044e2577d8746d5e935/lib/fast_jsonapi/instrumentation/skylight/normalizers/serialized_json.rb
• https://github.com/skylightio/skylight-ruby/blob/v2.0.0/skylight-core/lib/skylight/core/normalizers/action_controller/process_action.rb
• Creating Custom Probe for jsonapi-rb skylightio/skylight-ruby#113 (comment)

[mostlyobvious]

https://github.com/skylightio/skylight-ruby/blob/master/skylight-core/lib/skylight/core/normalizers.rb#L51-L68

[mostlyobvious]

• normalizers have to loaded quite early, before Skylight::Subscriber starts, should be ok to deliver them in a gem that is required in Rails application.rb via Bundler
• allowed tiers:

TIERS = %w[
  rack
  api
  app
  view
  db
  noise
  other
].freeze

[mostlyobvious]

[mostlyobvious]

class Dispatcher < ::Skylight::Core::Normalizers::Normalizer
  register "call.dispatcher.rails_event_store"

  CAT = "app.rails_event_store.dispatcher".freeze

  def normalize(_trace, _name, payload)
    [CAT, "#{payload[:subscriber]}#call", "Handle #{payload[:event].type}"]
  end
end

[wagenet]

@pawelpacana this looks good! If you're interested, we can integrate this into the main skylight gem.

[mostlyobvious]

@wagenet thanks! Integrating into skylight gem would be probably the best from the developer perspective.

Btw. is there any way to format the description? Like multiple lines for example?

[wagenet]

Right now we don't have a way to do it. You can file an issue at https://github.com/skylightio/skylight-ruby/issues/new and explain a bit more about what you'd like.