New Relixir

Instrument your Phoenix and Plug applications with New Relic.

New Relixir currently supports instrumenting bare-bones Plug endpoints, Phoenix controllers and Ecto repositories, to record response times of web transactions and database queries.

Documentation

Usage

The following instructions show how to add instrumentation with New Relixir to a hypothetical Phoenix application named MyApp.

Add new_relixir to your list of dependencies in mix.exs:
```
# mix.exs

defmodule MyApp.Mixfile do
  use Mix.Project

  # ...

  defp deps do
    [{:new_relixir, "~> 0.4"}]
  end
end
```
If you use the applications key (only for apps created before Elixir 1.4) in def application do, then you will also need to add new_relixir to it:
```
def application do
  [mod: {MyApp, []},
   applications: [:new_relixir]]
end
```
If your app does not have an applications key, skip this instruction.
Add your New Relic application name and license key to config/config.exs. You may wish to use environment variables to keep production, staging, and development environments separate:
```
# config/config.exs

config :new_relixir,
  application_name: System.get_env("NEWRELIC_APP_NAME"),
  license_key: System.get_env("NEWRELIC_LICENSE_KEY")
```

Add NewRelixir.Instrumenters.Phoenix to the list of instrumenters in your Endpoint configuration:

# config/config.exs

config :my_app, MyAppWeb.Endpoint,
  instrumenters: [NewRelixir.Instrumenters.Phoenix],
  # ...

If your app also uses Ecto, define a module to wrap your repository's methods with New Relic instrumentation:

# lib/my_app/repo.ex

defmodule MyApp.Repo do
  use Ecto.Repo, otp_app: :my_app

  defmodule NewRelic do
    use NewRelixir.Plug.Repo, repo: MyApp.Repo
  end
end

Now MyApp.Repo.NewRelic can be used as a substitute for MyApp.Repo. It will dispatch and instrument the response time for all Repo calls.

If you've defined custom functions on your Repo, you will need to define them on your wrapper module as well. In the wrapper module, simply call your repository's original function inside a closure that you pass to instrument_db:

# lib/my_app/repo.ex

defmodule MyApp.Repo do
  use Ecto.Repo, otp_app: :my_app

  def my_custom_operation(queryable, opts \\ []) do
    # ...
  end

  defmodule NewRelic do
    use NewRelixir.Plug.Repo, repo: MyApp.Repo

    def my_custom_operation(queryable, opts \\ []) do
      instrument_db(:my_custom_operation, queryable, opts, fn() ->
        MyApp.Repo.my_custom_operation(queryable, opts)
      end)
    end
  end
end

When using the wrapper module's my_custom_operation, the time it takes to call MyApp.Repo.my_custom_operation/2 will be recorded to New Relic.

Error Reporting

If you want to report all errors to new relic

Configure your router

# lib/my_app/router.ex

defmodule MyApp.Router do
  use MyApp, :router
  use NewRelixir.Plug.Exception

  ...
end

If you want to report caught errors

try do
  raise "oops"
catch
  kind, reason ->
    transaction =
      case NewRelixir.CurrentTransaction.get() do
        {:ok, transaction} -> transaction
        {:error, _} -> NewRelixir.CurrentTransaction.set(conn.request_path)
      end

    NewRelixir.Transaction.record_error(transaction, {kind, reason})

    # You may want to re-raise this exception
    :erlang.raise(kind, reason, System.stacktrace)
end

Upgrading from 0.3.x

Remove NewRelixir.Plug.Phoenix from your Plug pipeline and all further references to that module.
Add NewRelixir.Instrumenters.Phoenix to the list of instrumenters in your Endpoint configuration. See more in usage.

Passing a conn to the functions of your Repo wrapper is no longer required, calls to the wrapper can now be made the same way as calls to the original Repo:

# web/controllers/users.ex

defmodule MyApp.UserController do
  use MyApp.Web, :controller

  def index(conn, _params) do
    # Before
    users = Repo.all(User, conn: conn)

    # Now
    users = Repo.all(User)
  end
end