Build you a :telemetry for such learn!

This repo presents a minimal implementation of a :telemetry clone in Elixir.

You can view the original implementation of the library here.

The intention behind this repo is the serve as an artefact one can follow along to alongside this blog post.

Installation

If for some reason you want to use this library in your code, this package can be installed by adding build_you_a_telemetry to your list of dependencies in mix.exs:

def deps do
  [
    {:build_you_a_telemetry, "~> 0.1.0"}
  ]
end

Usage

You can emit telemetry events in your business logic via:

Telemetry.execute(
  [:web, :request, :done],
  %{latency: latency},
  %{request_path: request_path, status_code: status_code})

And you can implement handlers for these events via:

defmodule Handler do
  def handle_event([:web, :request, :done], measurements, metadata, _config) do
    Logger.info("[#{metadata.request_path}] #{metadata.status_code} sent in #{measurements.latency}")
  end
end

Which need to be attached via:

:ok = Telemetry.attach(
  "log-response-handler",
  [:web, :request, :done],
  &Handler.handle_event/4, nil
)

Quickstart

The only dependency and requirement for this library is Elixir itself. This library was developed with Elixir 1.10.4 so if anything doesn’t work, it might be best to try it out on that version.

I’ll be looking at maintaining this library as time goes on and Elixir itself updates and changes, but if you spot anything wrong feel free to send over a PR!

If you’re a nix or nixos user, this repository contains a shell.nix file which defines a development environment for you to use. Simply run nix-shell in this directory to activate it. Moreover, if you are a lorri user, simple run direnv allow and entering this project directory will activate this shell for you.