# Flame On

![Flame On - Phoenix LiveDashboard](assets/images/screenshot.png)

Add Flame Graphs to your Phoenix Application or LiveDashboard

## Getting Started

For more information on flame graphs and an introduction to Flame On, see [the announcement blog post](https://dockyard.com/blog/2022/02/22/profiling-elixir-applications-with-flame-graphs-and-flame-on)
## Installation

Add `:flame_on` to your dependencies:

```elixir
def deps do
  [
    {:flame_on, "~> 0.4.0"}
  ]
end
```

And then add Flame On as a LiveDashboard page or a LiveComponent in your LiveView page

### Flame On as a LiveDashboard page

Modify the `live_dashboard` call in your `Router`:

```elixir
live_dashboard "/dashboard",
  metrics: MyAppWeb.Telemetry,
  additional_pages: [
    flame_on: FlameOn.DashboardPage
  ]
```

You will now find a `Flame On` tab along the top of the LiveDashboard page

### Flame On as a LiveComponent in your own LiveView page

```elixir
<.live_component module={FlameOn.Component} id="flame_on" width="100%" height="100%" />
```

## Usage

Choose the Module, Function, and Arity of the function you want to profile, click "Flame On", and then trigger the function (e.g. make a web request in a new tab). Note that for Elixir modules, you will need to prefix them with `Elixir`, e.g. `Elixir.Phoenix.Controller`, while Erlang modules take simply the erlang module name, e.g. `cowboy_handler`. The default values of `cowboy_handler`/`execute`/`2` are the best way to capture a standard Phoenix Controller DeadView request or the DeadView request that kicks off a LiveView request.

### Zooming

Clicking a block will zoom the flamegraph to that block and recalculate the percents for the blocks such that the clicked block is now 100%. You can return to a higher level block by clicking the link for it above the blocks.

## Running in Production

Flame On should not be run in critical production environments. Flame On uses eFlambe, which uses Meck under the hood. This swaps out beam code paths and injects mock code that includes tracing. If you do need to use Flame On in a critical production node to diagnose a specific issue, I recommend rebuilding or restarting that node after running it.

## Running in a Release

Meck swaps out code paths and therefore you will need to include the beam files in your release. By default these are stripped, so in your release definition in `mix.exs` add the `strip_beams: false` flag:

```elixir
releases: [
  my_app_web: [
    ...
    strip_beams: false
  ],
```

You may also need to explicitly include `:meck` as a dependency if it can't find it when trying to run in a release.

## Authors ##

* [Mike Binns](https://github.com/TheFirstAvenger)

[We are very thankful for the many contributors](https://github.com/DockYard/flame_on/graphs/contributors)

## Versioning ##

This library follows [Semantic Versioning](https://semver.org)

## Looking for help with your Elixir project? ##

[At DockYard we are ready to help you build your next Elixir project](https://dockyard.com/phoenix-consulting). We have a unique expertise
in Elixir and Phoenix development that is unmatched. [Get in touch!](https://dockyard.com/contact/hire-us)

At DockYard we love Elixir! You can [read our Elixir blog posts](https://dockyard.com/blog/categories/elixir)

## Legal ##

[DockYard](https://dockyard.com/), Inc. © 2022

[@DockYard](https://twitter.com/DockYard)

[Licensed under the MIT license](https://www.opensource.org/licenses/mit-license.php)