# OpentelemetryPhoenix

[![EEF Observability WG project](https://img.shields.io/badge/EEF-Observability-black)](https://github.com/erlef/eef-observability-wg)
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Telemetry handler that creates Opentelemetry spans from Phoenix events.

After installing, setup the handler in your application behaviour before your
top-level supervisor starts.

```elixir
OpentelemetryPhoenix.setup()
```

See the documentation for `OpentelemetryPhoenix.setup/1` for additional options that
may be supplied.


## Installation

```elixir
def deps do
  [
    {:opentelemetry_phoenix, "~> 1.0.0-rc"}
  ]
end
```

## Note on phoenix integration

`OpentelemetryPhoenix` requires phoenix to use `Plug.Telemetry` in order to correctly trace endpoint calls.

The `endpoint.ex` file should look like:
```Elixir
defmodule MyApp.Endpoint do
  use Phoenix.Endpoint, otp_app: :my_app
  ...
  plug Plug.Telemetry, event_prefix: [:phoenix, :endpoint]
  ...
end
```
The [Phoenix endpoint.ex template](https://github.com/phoenixframework/phoenix/blob/v1.6.0/installer/templates/phx_web/endpoint.ex#L39) can be used as a reference