# Hummingbird
A plug to correlate events between services in two lines of Elixir.

Given appropriate trace headers, ships an event for router and response calls.

**This library is under active development**

## To Use

defmodule YourAppWeb.YourController do
  use YourAppWeb, :controller

  plug Hummingbird, service_name: "your_service_name"

and add the `Hummingbird.Telemetry` child to your supervision tree:

defmodule YouApp.Application do

  def start(_type, _args) do
    children = [

    Supervisor.start_link(children, strategy: :one_for_one, name: YourApp.Supervisor)


## Configuration
**Configure OpenCensus**
In your config.exs:
# configure opencensus
config :opencensus,
  reporters: [{Opencensus.Honeycomb.Reporter, []}],
  send_interval_ms: 1000
**Set the dataset per environment**
In your dev, prod, exs files:

# configure write key per dataset/environment
# we use environment variables to protect the secret. It doesn't matter how you
# set the value.  Choose your own adventure.

config :opencensus_honeycomb,
  dataset: "your_dataset_name_goes_here",
  write_key: "${HONEYCOMB_WRITE_KEY}"

## Assumptions
Currently, it looks for `x-b3-spanid` and `x-b3-traceid` headers on incoming request to create the trace.

## Current Example

![Image of Trace Waterfall](images/waterfall.png)

## Thanks

Wraps around