Creating Elixir App Binaries Using Bakeware

As the king once said:

Just generate a binary and it’ll be great.

Just like in other languages like GOlang, with Bakeware we can compile an Elixir app into a single binary. Built on the excellent releases feature of Elixir in the latest versions, Bakeware even offers compression strategies using Zstandard.

Inside the Bakeware repo, there are some examples of how to create binaries for different scenarios (CLI apps, Phoenix, etc.).

To demonstrate the tool, I will create a binary for an app I developed for banner grabbing called binoculo. Since we use the tool via CLI, distributing/releases a binary for this type of application becomes really interesting.

Preparing the Ground

• You need to clone Bakeware outside the directory you want to compile.
• Next, some modifications are needed in the app’s mix.exs file:

def application do
  [
    ...,
    mod: {Binoculo.CLI, []}
  ]
end

defp release do
  [
    binoculo: [
      overwrite: true,
      steps: [:assemble, &Bakeware.assemble/1],
      strip_beams: Mix.env() == :prod
    ]
  ]
end

defp deps do
  [
    {:iplist, "~> 1.0.0"},
    {:bakeware, path: "../bakeware", runtime: false}
  ]
end

• In the application function, we add the mod key to pass user arguments to the main function of the Binoculo.CLI module.

• In the release function, we define the app name via the first key in the keyword list:

  • overwrite: to replace a pre-existing binary
  • steps: Compilation steps using the assemble/1 function from the Bakeware module
  • strip_beams: removes debug info related to beam

• And in deps, we basically include the library specifying the directory. The runtime: false option removes compile-time dependencies, so it’s important to set it to false as recommended by the documentation.

Lastly, in the actual module, which in this case is Binoculo.CLI, we need to change the main function to receive command-line arguments:

defmodule Binoculo.CLI do
  use Bakeware.Script

  ...

  @impl Bakeware.Script
  def main(args) do
    IO.puts("Binoculo CLI\n")
    args |> parse_args

    0
  end

This way, the arguments can still be parsed as they were using escript.

After that, with the mix release command, we can generate the binary:

girorme@DESKTOP-MN7HFPO ~/repositorios/binoculo (binary-release) $ mix release
==> elixir_make
Compiling 1 file (.ex)
Generated elixir_make app

...

Once done, just run the binary inside the _build/prod/rel/bakeware folder:

girorme@DESKTOP-MN7HFPO ~/repositorios/binoculo/_build/prod/rel/bakeware (binary-release) $ ./binoculo -h
Binoculo CLI

Binoculo 1.0.0 - Usage:
--head - Send an HTTP HEAD to server
--help | -h - Show Binoculo usage
--ip - CIDR notation/ip_range -> 192.168.0.1/24|192.168.0.1..192.168.0.255
--verbose - Show refused/error connections
-p | --port - Port to scan
-r | --read - Search for a specific word in response
-t | --threads - Number of threads

Ex: bin/binoculo --ip "192.168.0.1/24" -p 8080 -t 45 --head

For more information and use cases: Bakeware-repo

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