neiam /gitgud

defmodule GitGud.Application do
  # See https://hexdocs.pm/elixir/Application.html
  # for more information on OTP Applications
  @moduledoc false

  use Application

  @impl true
  def start(_type, _args) do
    # Route error-level logs + process crash reports (incl. LiveView and
    # GenServer terminations) to Sentry. No-ops when SENTRY_DSN is unset.
    :logger.add_handler(:sentry_handler, Sentry.LoggerHandler, %{
      level: :error,
      config: %{metadata: [:file, :line], capture_log_messages: true}
    })

    topologies = Application.get_env(:libcluster, :topologies, [])

    children =
      [
        GitGudWeb.Telemetry,
        GitGud.Repo,
        {DNSCluster, query: Application.get_env(:git_gud, :dns_cluster_query) || :ignore}
      ] ++
        cluster_children(topologies) ++
        [
          {Phoenix.PubSub, name: GitGud.PubSub},
          # Multilevel supervises its L1 + L2 children itself per the
          # `levels:` config — listing them here would double-start.
          GitGud.Cache,
          {Oban, Application.fetch_env!(:git_gud, Oban)},
          GitGud.Federation.RateLimiter,
          GitGud.Ssh.Server,
          GitGudWeb.Endpoint
        ]

    # See https://hexdocs.pm/elixir/Supervisor.html
    # for other strategies and supported options
    opts = [strategy: :one_for_one, name: GitGud.Supervisor]
    Supervisor.start_link(children, opts)
  end

  # When `:libcluster` has no topology configured (dev / test / single-
  # node prod), skip Cluster.Supervisor entirely. In a multi-replica
  # prod with the Kubernetes topology defined in runtime.exs, libcluster
  # discovers peer pods and connects them; once the cluster forms,
  # `GitGud.Cache.L2`'s Replicated adapter joins its pg group across
  # nodes.
  defp cluster_children([]), do: []

  defp cluster_children(topologies) do
    [{Cluster.Supervisor, [topologies, [name: GitGud.ClusterSupervisor]]}]
  end

  # Tell Phoenix to update the endpoint configuration
  # whenever the application is updated.
  @impl true
  def config_change(changed, _new, removed) do
    GitGudWeb.Endpoint.config_change(changed, removed)
    :ok
  end
end