Fly Cloud for Oban Auto Scaling

fly.ex

defmodule Oban.Pro.Clouds.Fly do
  @moduledoc false

  @behaviour Oban.Pro.Cloud

  @enforce_keys [:app_id, :auth_token, :regions]
  defstruct @enforce_keys

  @url "https://api.fly.io/graphql"

  @query """
  mutation ScaleApp($input: ScaleAppInput!) {
    scaleApp(input: $input) {
      delta {
        fromCount
        toCount
      }
    }
  }
  """

  @impl Oban.Pro.Cloud
  def init(opts) do
    struct!(__MODULE__, opts)
  end

  @impl Oban.Pro.Cloud
  def scale(quantity, %{app_id: app_id, auth_token: auth_token, regions: regions}) do
    headers = [
      {"Content-Type", "application/json"},
      {"Accept", "application/json"},
      {"Authorization", "Bearer #{auth_token}"}
    ]

    regions = Enum.map(regions, &%{region: &1, count: quantity})

    body = %{
      query: @query,
      variables: %{input: %{appId: app_id, regions: regions}}
    }

    Req.post!(@url, json: body, headers: headers)
  end
end