CalderaApi

Elixir implementation of Caldera API.

The server is implemented as Plugs on top of Cowboy.

Installation

First make sure that elixir is installed:

• https://elixir-lang.org/install.html

Then run the following to start the API.

$ NATS_HOST="<nats_host>" SONIC_HOST="<sonic_host>" iex -S mix

Code Organization

Common plugs are organized under a single subdirectory:

• lib/caldera_api/plugs

While endpoint-specific plugs are organized under respective subdirectories:

• lib/caldera_api/symboliker
• lib/caldera_api/threat_proximity

Endpoints can store shared constants in a file designated to be loaded with a use call.

# lib/caldera_api/foo/constants.ex

defmodule CalderaApi.Foo.Constants do

  defmacro __using__(_) do
    @foo "bar"
    @baz 251
  end

end

These constants can be shared by the endpoint-specific plugs in the following manner.

# lib/caldera_api/foo/plug.ex

defmodule CalderaApi.Foo.Plug do

  use CalderaApi.Foo.Constants
  use Plug.Builder

  plug :myplug

  def myplug(conn, _opts) do
    conn
    |> send_resp(@baz, @foo)
  end

end

Important note when using halt() in Plugs.

halt() only prevents downstream plugs from being invoked.

Manual chainings of plugs will not be stopped and without careful watch can cause "already sent" errors.

# lib/caldera_api/bar/plug.ex

defmodule CalderaApi.Bar.Plug do

  use CalderaApi.Bar.Constants
  use Plug.Builder

  plug :myplug

  def myplug(conn, opts) do
    conn = CalderaApi.Foo.Plug.call(
      conn,
      CalderaApi.Foo.Plug.init(opts)
    )

    if conn.state == :sent do
      conn
    else
      conn
      |> put_status(200)
      |> send_resp()
    end
  end

end

Distribution Statement "A" (Approved for Public Release, Distribution Unlimited).