# NervesHubLinkCommon

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Common library that should be shared between
the [websocket](https://github.com/nerves-hub/nerves_hub_link) and [http](https://github.com/nerves-hub/nerves_hub_link_http)
connections.

Handles resumable HTTP streams to fwup.

**NOTE**

You probably don't need this library directly. See the above linked libraries.

## Usage

The main API to this application is `NervesHubLinkCommon.UpdateManager`.
It is meant to be started as a child in a supervision tree:

```elixir
require Logger
alias NervesHubLinkCommon.{UpdateManager, FwupConfig}

def handle_fwup_message({:ok, _status, message}), do: Logger.info("Firmware update complete: #{message} going down for reboot...")
def handle_fwup_message({:warning, _status, message}), do: Logger.warn("Firmware update warning: #{message}")
def handle_fwup_message({:error, _status, message}), do: Logger.error("Firmware update failed: #{message}")
def handle_fwup_message({:progress, percent}), do: Logger.error("Firmware update progress: #{percent}%")

def update_available(%{"firmware_url" => _}) do
  if SomeExternalApi.is_now_a_good_time_for_a_firmware_update?() do
    :apply
  else
    {:reschedule, 60_000}
  end
end

def init(_) do
  fwup_config = %FwupConfig{
      fwup_public_keys: ["Qqyf/7JrIt06+xzvF6a5CgNj8/CZfHUemTa32R8effM="],
      fwup_devpath: "/dev/mmcblk0p1",
      handle_fwup_message: &handle_fwup_message/1,
      update_available: &update_available/1
  }
  children = [{UpdateManager, fwup_config}]
  Supervisor.init(children, [strategy: :one_for_one])
end
```

## License

Copyright (C) 2018-21 The Nerves Project Authors <developers@nerves-project.org>

    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
    You may obtain a copy of the License at [http://www.apache.org/licenses/LICENSE-2.0](http://www.apache.org/licenses/LICENSE-2.0)

    Unless required by applicable law or agreed to in writing, software
    distributed under the License is distributed on an "AS IS" BASIS,
    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    See the License for the specific language governing permissions and
    limitations under the License.