Ecto Arc S3 Image Uploader Not Working

form.html.eex

<%= form_for @changeset, @action, [multipart: true], fn f -> %>
  <%= if @changeset.action do %>
    <div class="alert alert-danger">
      <p>Oops, something went wrong! Please check the errors below.</p>
    </div>
  <% end %>

  <div class="form-group">
    <%= label f, :title, class: "control-label" %>
    <%= text_input f, :title, class: "form-control" %>
    <%= error_tag f, :title %>
  </div>

  <div class="form-group">
    <%= label f, :image, class: "control-label" %>
    <%= file_input f, :image, class: "form-control" %>
    <%= error_tag f, :image %>
  </div>

  <div class="form-group">
    <%= label f, :description, class: "control-label" %>
    <%= textarea f, :description, class: "form-control" %>
    <%= error_tag f, :description %>
  </div>

  <div class="form-group">
    <%= label f, :url, class: "control-label" %>
    <%= url_input f, :url, class: "form-control" %>
    <%= error_tag f, :url %>
  </div>

  <div class="form-group">
    <%= label f, :draft, class: "control-label" %>
    <%= checkbox f, :draft, class: "form-control" %>
    <%= error_tag f, :draft %>
  </div>

  <div class="form-group">
    <%= submit "Submit", class: "btn btn-primary" %>
  </div>
<% end %>

image.ex

defmodule Estrada.Image do
  use Arc.Definition

  # Include ecto support (requires package arc_ecto installed):
  use Arc.Ecto.Definition

  @acl :public_read

  # @versions [:original]

  # To add a thumbnail version:
  @versions [:original, :thumb]

  # Whitelist file extensions:
  # def validate({file, _}) do
  #   ~w(.jpg .jpeg .gif .png) |> Enum.member?(Path.extname(file.file_name))
  # end

  # Define a thumbnail transformation:
  def transform(:thumb, _) do
    {:convert, "-strip -thumbnail 250x250^ -gravity center -extent 250x250 -format png", :png}
  end
  def transform(:original, _), do: :noaction

  # Override the persisted filenames:
  def filename(version, {file, scope}) do
    # version
    "#{version}_#{file.file_name}"
  end

  # Override the storage directory:
  def storage_dir(version, {file, scope}) do
    "marijaserifovic/news/" #{scope.id}"
  end

  # Provide a default URL if there hasn't been a file uploaded
  def default_url(version, scope) do
    # "/images/avatars/default_#{version}.png"
    "marijaserifovic/maxresdefault.jpg"
  end

  # Specify custom headers for s3 objects
  # Available options are [:cache_control, :content_disposition,
  #    :content_encoding, :content_length, :content_type,
  #    :expect, :expires, :storage_class, :website_redirect_location]
  #
  # def s3_object_headers(version, {file, scope}) do
  #   [content_type: Plug.MIME.path(file.file_name)]
  # end
end

news_article.ex

defmodule Estrada.NewsArticle do
  use Estrada.Web, :model
  use Arc.Ecto.Model

  schema "news" do
    field :title, :string
    field :image, Estrada.Image.Type
    field :description, :string
    field :url, :string
    field :draft, :boolean, default: false

    timestamps
  end

  @required_fields ~w(title description draft)
  @optional_fields ~w(url)

  @required_file_fields ~w(image)
  @optional_file_fields ~w()


  @doc """
  Creates a changeset based on the `model` and `params`.

  If no params are provided, an invalid changeset is returned
  with no validation performed.
  """
  def changeset(model, params \\ :empty) do
    model
    |> cast(params, @required_fields, @optional_fields)
    |> cast_attachments(params, @required_file_fields, @optional_file_fields)
  end
end