A behaviour to help orchestrate the complete workflow of downloading and installing/applying firmware updates.

This module provides a set of callbacks that must be implemented by any updater module. The callbacks are used to start the update process, handle messages from the NervesHubLink.Downloader, decide when to start the installation via the Fwup library, and perform any necessary cleanup.

Creating a new updater module involves implementing the following callbacks:

• start_update/3: Called by NervesHubLink.UpdateManager to start the update process.
• start/1: Callback to setup, prepare, and trigger the download.
• handle_downloader_message/2: Process messages from the NervesHubLink.Downloader.
• handle_fwup_message/2: Process messages received from the Fwup library
• cleanup/1: Perform any necessary cleanup.

To simplify the implementation of these callbacks, you can use the provided NervesHubLink.UpdateManager.Updater module as a base. This module provides default implementations for the callbacks, which you can override as needed.

Example Usage

Here's an example of how to create a new updater module using the provided NervesHubLink.UpdateManager.Updater module as a base:

defmodule MyApp.Updater do
  use NervesHubLink.UpdateManager.Updater

  def start_update(update_info, fwup_config, fwup_public_keys) do
    # Implement the start_update callback
  end

  def start(state) do
    # eg. Setup a temporary directory for storing downloaded files
  end

  def handle_downloader_message(message, state) do
    # eg. Forward packets to the Fwup module
  end

  # Use the default implementation provided by the base module
  #
  # def handle_fwup_message(message, state) do
  # end

  def cleanup(state) do
    # eg. Remove any temporary files or resources created during the update process
  end

  def log_prefix do
    "[MyApp.Updater]"
  end
end