# SpandexPhoenix

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Phoenix and Plug integrations for the [Spandex] tracing library.


## Usage

Add `:spandex_phoenix` to your dependencies in `mix.exs`:

def deps do
    {:spandex_phoenix, "~> 1.1"}

Configure it to use your desired `Spandex.Tracer` module in `config.exs`:

config :spandex_phoenix, tracer: MyApp.Tracer

### Usage: Phx >= 1.5 (Telemetry)

**Upgrade Note**: *If you're updating your SpandexPhoenix code from using it with previous versions of Phoenix,
you must first remove all the code detailed in `Usage: Plug & Phx < 1.5` before following
telemetry installation instructions below.*

SpandexPhoenix supports using Phoenix 1.5's Telemetry events to create spans for
`Phoenix.Controller` timing, with the `resource` name set to the controller action.

To attach `Spandex.Telemetry`'s event handlers, call `SpandexPhoenix.Telemetry.install/{0,1}`
during your application's startup:

defmodule MyApp.Application do
  def start(_, _) do
    # ...
    # ...

See `Spandex.Telemetry.install/1` documentation for event handler options.

### Usage: Plug & Phx < 1.5

Add `use SpandexPhoenix` to the appropriate module. This will "wrap" the
module with tracing and error-reporting via Spandex.

Phoenix integration:

defmodule MyAppWeb.Endpoint do
  use Phoenix.Endpoint, otp_app: :my_app
  use SpandexPhoenix

  # ...

If you use Phoenix, you don't need to use the following integration most likely, otherwise, you get the error messages like

[error] Tried to start a trace over top of another trace

Plug integration:

defmodule MyApp.Router do
  use Plug.Router
  use SpandexPhoenix

  # ...

#### Customizing Traces

Traces can be customized and filtered by passing options to the `use SpandexPhoenix` macro.
See the [documentation for SpandexPhoenix] for more information.

#### Integrating with Phoenix Instrumentation

If you are using Phoenix and you configure `SpandexPhoenix.Instrumenter` in
your Phoenix `instrumenters` list, you will automatically get spans created for
`Phoenix.Controller` and `Phoenix.View` timing, with the `resource` set to the
name of the controller action or view name.

Note that this should be used in addition to the `use SpandexPhoenix`
macro to start the trace and top-level span, as the instrumenter only creates
child spans, assuming that the trace will already have been created.

Configure your Phoenix `Endpoint` to use this library as one of its

config :my_app, MyAppWeb.Endpoint,
  # ... existing config ...
  instrumenters: [SpandexPhoenix.Instrumenter]

More details can also be found in the docs on [Hexdocs].

## Copyright and License

Copyright (c) 2021 Zachary Daniel & Greg Mefford

Released under the MIT License, which can be found in [](./

[documentation for SpandexPhoenix]: