module is not available in :prod env

elasticsearch.ex

# lib/example/elasticsearch.ex
defmodule Example.Elasticsearch do
  alias Example.Repo
  alias Example.Model.{Library, Book}

  @elastic_url Application.get_env(:hobs, :elastic_url)
  @elastic_index Application.get_env(:hobs, :elastic_index)

  def reindex_libraries do
    #...
  end
  def reindex_books do
    #...
  end
  def clear_all do
    #...
  end
end

elasticsearch_task.ex

# lib/mix/tasks/elasticsearch.ex
defmodule Mix.Tasks.Example.Elasticsearch do
  use Mix.Task
  require Example.Elasticsearch

  @shortdoc "Reindex elasticsearch with current data"

  def run(_args) do
    unless Application.get_env(:phoenix, :serve_endpoints) do
      Mix.Task.run "app.start", []
    end
    Example.Elasticsearch.clear_all
    Example.Elasticsearch.reindex_libraries
    Example.Elasticsearch.reindex_books
  end
end