Integrating AppSignal into Phoenix

The AppSignal for Elixir package integrates with Phoenix. To set up the integration, please follow our installation guide.

This page will describe further ways of configuring AppSignal for the Phoenix framework. To add more custom instrumentation to your Phoenix application, read the Elixir instrumentation documentation.

More information can be found in the AppSignal Hex package documentation.

Installation

1. The AppSignal instrumentation for Phoenix is part of a separate package, which depends on the primary appsignal package. Add the appsignal_phoenix package to your mix.exs file.

   # mix.exs
   defmodule AppsignalPhoenixExample.MixProject do
     # ...
    
     defp deps do
       [
         {:phoenix, "~> 1.5.3"},
         {:appsignal_phoenix, "~> 2.0"}
         # ...
       ]
     end
   end

2. Then run mix deps.get.

3. Then run mix appsignal.install YOUR_PUSH_API_KEY.

Incoming HTTP requests

To start logging HTTP requests in your Phoenix app, make sure you use the Appsignal.Phoenix module in your endpoint.ex file.

defmodule AppsignalPhoenixExampleWeb.Endpoint do
  use Phoenix.Endpoint, otp_app: :appsignal_phoenix_example
  use Appsignal.Phoenix
 
  # ...
end

This will create a transaction for every HTTP request which is performed on the endpoint.

Template rendering

It's possible to instrument how much time it takes each template render, including subtemplates (partials), in your Phoenix application.

To enable this for AppSignal, add use Appsignal.Phoenix.View to the view/0 function in your app's web module, after use Phoenix.View:

defmodule AppsignalPhoenixExampleWeb do
  # ...
 
  def view do
    quote do
      use Phoenix.View,
        root: "lib/appsignal_phoenix_example_web/templates",
        namespace: AppsignalPhoenixExampleWeb
 
      use Appsignal.Phoenix.View
 
      # Import convenience functions from controllers
      import Phoenix.Controller, only: [get_flash: 1, get_flash: 2, view_module: 1]
 
      # Include shared imports and aliases for views
      unquote(view_helpers())
    end
  end
 
  # ...
end

Channels

Channel instrumentation with a channel's handle

Incoming channel requests can be instrumented by wrapping the code in your handle_in/3 functions with Appsignal.Phoenix.Channel.instrument/5:

defmodule AppsignalPhoenixExampleWeb.RoomChannel do
  use Phoenix.Channel
 
  # ...
 
  def handle_in("new_msg", %{"body" => body} = params, socket) do
    Appsignal.Phoenix.Channel.instrument(__MODULE__, "new_msg", params, socket, fn ->
      broadcast!(socket, "new_msg", %{body: body})
      {:noreply, socket}
    end)
  end
end

Alternatively, you can use function decorators to instrument channels. While less flexible than the instrumentation function, decorators minimize the amount of code you have to add to your application's channels.

defmodule SomeApp.MyChannel do
  use Appsignal.Instrumentation.Decorators
 
  @decorate channel_action()
  def handle_in("ping", _payload, socket) do
    # your code here..
  end
end

Channel events will be displayed under the "Background jobs" tab, showing the channel module and the action argument that you entered.

LiveView

-> Note: The LiveView Telemetry integration is available from AppSignal for Phoenix version 2.1.0 onward.

AppSignal's LiveView Telemetry integration automatically instruments live view event.

To set it up, call Appsignal.Phoenix.LiveView.attach/0 to attach the LiveView Telemetry handlers. We recommend calling this function from your app's application.ex:

defmodule AppsignalPhoenixExample.Application do
  # ...
  def start(_type, _args) do
    Appsignal.Phoenix.LiveView.attach() # <--- attach the LiveView Telemetry handlers
    children = [
      # Start the Ecto repository
      AppsignalPhoenixExample.Repo,
      # Start the Telemetry supervisor
      AppsignalPhoenixExampleWeb.Telemetry,
      # Start the PubSub system
      {Phoenix.PubSub, name: AppsignalPhoenixExample.PubSub},
      # Start the Endpoint (http/https)
      AppsignalPhoenixExampleWeb.Endpoint
      # Start a worker by calling: AppsignalPhoenixExample.Worker.start_link(arg)
      # {AppsignalPhoenixExample.Worker, arg}
    ]
    # See https://hexdocs.pm/elixir/Supervisor.html
    # for other strategies and supported options
    opts = [strategy: :one_for_one, name: AppsignalPhoenixExample.Supervisor]
    Supervisor.start_link(children, opts)
  end
end

AppSignal will now automatically instrument all mount, handle_event and handle_param events, meaning you'll receive both performance and error insights into your live views.

Helper functions

A LiveView action is instrumented by wrapping its contents in a Appsignal.Phoenix.LiveView.instrument/4 block.

Given a live view that updates its own state every second, we can add AppSignal instrumentation by wrapping both the mount/2 and handle_info/2 functions with a Appsignal.Phoenix.LiveView.instrument/4 call:

defmodule AppsignalPhoenixExampleWeb.ClockLive do
  use Phoenix.LiveView
  import Appsignal.Phoenix.LiveView, only: [instrument: 4]
 
  def render(assigns) do
    AppsignalPhoenixExampleWeb.ClockView.render("index.html", assigns)
  end
 
  def mount(_session, socket) do
    # Wrap the contents of the mount/2 function with a call to
    # Appsignal.Phoenix.LiveView.instrument/4
 
    instrument(__MODULE__, "mount", socket, fn ->
      :timer.send_interval(1000, self(), :tick)
      {:ok, assign(socket, state: Time.utc_now())}
    end)
  end
 
  def handle_info(:tick, socket) do
    # Wrap the contents of the handle_info/2 function with a call to
    # Appsignal.Phoenix.LiveView.instrument/4:
 
    instrument(__MODULE__, "tick", socket, fn ->
      {:ok, assign(socket, state: Time.utc_now())}
    end)
  end
end

Calling one of these functions in your app will now automatically create a sample that's sent to AppSignal. These are displayed under the :live_view namespace.

Instrumentation for included Plugs

Exceptions in included Plugs are automatically caught by AppSignal, but performance samples need to be set up manually using the custom instrumentation helpers or decorators. See the Plug documentation for more information.

Custom instrumentation

Add custom instrumentation to keep track of more complex code and get more complete breakdowns of slow requests.