https://github.com/lorenzosinisi/woke

A watchdog library for Elixir
https://github.com/lorenzosinisi/woke

Last synced: 3 days ago
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A watchdog library for Elixir

• Host: GitHub
• URL: https://github.com/lorenzosinisi/woke
• Owner: lorenzosinisi
• License: apache-2.0
• Created: 2020-07-31T07:01:47.000Z (over 4 years ago)
• Default Branch: master
• Last Pushed: 2021-01-13T15:25:56.000Z (almost 4 years ago)
• Last Synced: 2024-12-09T15:58:41.393Z (19 days ago)
• Language: Elixir
• Homepage:
• Size: 13.7 KB
• Stars: 1
• Watchers: 2
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# Woke

## Monitor a new external resource

Create 2 modules and add the supervisor to your children in application.ex

1. Create the interface for the external resource, for instance one named Postgres:

```elixir

defmodule MyApp.Woke.Postgres do

  @moduledoc false

  @behaviour Woke.ExternalResource

  @impl Woke.ExternalResource

  def try_connect(opts \\ []) do

    try do

      Ecto.Adapters.SQL.query(MyApp.Repo, "select 1", [])

      :connected

    rescue

      error ->

        {:error, error}

    catch

      _, error ->

        {:error, error}

    end

  end

end

```

2. Configure the external resource being monitored using a GenServer: 

```elixir

defmodule MyApp.Woke.PostgresConnections do

  use Supervisor

  alias Woke.ExternalResource

  alias MyApp.Woke.Postgres

  def start_link(_opts) do

    Supervisor.start_link(__MODULE__, [], name: __MODULE__)

  end

  @impl true

  def init(_opts) do

    children = all_child_specs()

    Supervisor.init(children, strategy: :one_for_one)

  end

  defp all_child_specs() do

    database_number = [1,2,3]

    Enum.map(database_number, fn shard_id ->

      opts = [

        name: "postgres_#{shard_id}",

        check_every: :timer.seconds(30),

        try_connect_mod: Postgres,

        timeout: :timer.seconds(3)

      ]

      Supervisor.child_spec({ExternalResource, opts}, id: :"postgres_#{shard_id}")

    end)

  end

end

```

3. Add `MyApp.Woke.PostgresConnections` to your app supervisor children list:

```elixir

  use Application

  # See https://hexdocs.pm/elixir/Application.html

  # for more information on OTP Applications

  def start(_type, _args) do

    import Supervisor.Spec

   :gen_event.swap_handler(

        :alarm_handler,

        {:alarm_handler, :swap},

        {Woke.AlarmHandler, :ok}

    )

    # Define workers and child supervisors to be supervised

    children = [

      supervisor(MyApp.Endpoint, []),

      MyApp.Woke.PostgresConnections

    ]

    opts = [strategy: :one_for_one, name: MyApp.Supervisor]

    Supervisor.start_link(children, opts)

  end

```