PhoenixProfiler

Provides a development tool that gives detailed information about the execution of any request.

Never enable it on production servers as it exposes sensitive data about your web application.

Built-in Features

• Request/Response - status code, params, headers, cookies, etc.

• Routing - endpoint, router, controller/live view, action, etc.

• Basic diagnostics - response time, memory

• Inspect LiveView crashes

• Inspect Ecto queries (Coming Soon)

• Swoosh mailer integration (Coming Soon)

Installation

To start using the profiler, you will need the following steps:

1. Add the phoenix_profiler dependency
2. Enable the profiler on your Endpoint
3. Configure LiveView
4. Add the PhoenixProfiler plug
5. Mount the profiler on your LiveViews
6. Add the profiler page on your LiveDashboard (optional)

1. Add the phoenix_profiler dependency

Add phoenix_profiler to your mix.exs:

{:phoenix_profiler, "~> 0.2.0"}

2. Enable the profiler on your Endpoint

PhoenixProfiler is disabled by default. In order to enable it, you must update your endpoint's :dev configuration to include the :phoenix_profiler option:

# config/dev.exs
config :my_app, MyAppWeb.Endpoint,
  phoenix_profiler: []

All web configuration is done inside the :phoenix_profiler key on the endpoint.

The following options are available:

• :enable - When set to false, disables profiling by default. You can always enable profiling on a request via enable/1. Defaults to true.

• :profiler_link_base - The base path for generating links on the toolbar. Defaults to "/dashboard/_profiler".

• :toolbar_attrs - HTML attributes to be given to the element injected for the toolbar. Expects a keyword list of atom keys and string values. Defaults to [].

4. Configure LiveView

If LiveView is already installed in your app, you may skip this section.

The Phoenix Web Debug Toolbar is built on top of LiveView. If you plan to use LiveView in your application in the future we recommend you follow the official installation instructions. This guide only covers the minimum steps necessary for the toolbar itself to run.

Update your endpoint's configuration to include a signing salt. You can generate a signing salt by running mix phx.gen.secret 32 (note Phoenix v1.5+ apps already have this configuration):

# config/config.exs
config :my_app, MyAppWeb.Endpoint,
  live_view: [signing_salt: "SECRET_SALT"]

5. Add the PhoenixProfiler plug

Add the PhoenixProfiler plug within the code_reloading? block on your Endpoint (usually in lib/my_app_web/endpoint.ex):

  if code_reloading? do
    # plugs...
    plug PhoenixProfiler
  end

6. Mount the profiler on your LiveViews

Note this section is required only if you are using LiveView, otherwise you may skip it.

Add the profiler hook to the live_view function on your web module (usually in lib/my_app_web.ex):

  def live_view do
    quote do
      # use...

      on_mount PhoenixProfiler

      # view helpers...
    end
  end

This is all. Run mix phx.server and observe the toolbar on your browser requests.

7. Add the profiler page on your LiveDashboard (optional)

Note this section is required for the LiveDashboard integration. If you are not using LiveDashboard, you may technically skip this step, although it is highly recommended that you install LiveDashboard to enjoy all the features of PhoenixProfiler.

Add the dashboard definition to the list of :additional_pages on the live_dashboard macro in your router (usually in lib/my_app_web/router.ex):

live_dashboard "/dashboard",
  additional_pages: [
    _profiler: {PhoenixProfiler.Dashboard, []}
    # additional pages...
  ]

Troubleshooting

Exception raised with other on_mount hooks

If after enabling the profiler, you see an error like the following:

** (exit) an exception was raised:
** (RuntimeError) cannot attach hook with id :active_tab on :handle_params because the view was not mounted at the router with the live/3 macro

Then you need to add an extra clause on your on_mount/4 function:

def on_mount(_arg, :not_mounted_at_router, _session, socket) do
  {:cont, socket}
end

This is true for any handle_params hooks that will be invoked for LiveView modules not mounted at the router (i.e. via live_render/3), and the web debug toolbar is no exception.

Contributing

For those planning to contribute to this project, you can run a dev app with the following commands:

$ mix setup
$ mix dev

Alternatively, run iex -S mix dev if you also want a shell.

License

MIT License. Copyright (c) 2021 Michael Allen Crumm Jr.