# 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.
## To Use
```elixir
defmodule YourAppWeb.YourController do
use YourAppWeb, :controller
plug Hummingbird, service_name: "your_service_name"
end
```
and add the `Hummingbird.Telemetry` child to your supervision tree:
```elixir
defmodule YouApp.Application do
# ..
def start(_type, _args) do
children = [
Hummingbird.Telemetry,
# ..
]
Supervisor.start_link(children, strategy: :one_for_one, name: YourApp.Supervisor)
end
# ..
end
```
## Configuration
**Configure OpenCensus**
In your config.exs:
```elixir
# configure opencensus
config :opencensus,
reporters: [{Opencensus.Honeycomb.Reporter, []}],
send_interval_ms: 1000
```
**Set the dataset per environment**
In your dev, prod, exs files:
```elixir
# 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
## Thanks
Wraps around https://github.com/open-telemetry/opentelemetry-erlang
