federation_status: New endpoint showing unreachable instances

lib/pleroma/instances.ex

@@ -11,6 +11,7 @@ defmodule Pleroma.Instances do
   defdelegate reachable?(url_or_host), to: @adapter
   defdelegate set_reachable(url_or_host), to: @adapter
   defdelegate set_unreachable(url_or_host, unreachable_since \\ nil), to: @adapter
+  defdelegate get_consistently_unreachable(), to: @adapter
 
   def set_consistently_unreachable(url_or_host),
     do: set_unreachable(url_or_host, reachability_datetime_threshold())

lib/pleroma/instances/instance.ex

@@ -119,6 +119,17 @@ defmodule Pleroma.Instances.Instance do
 
   def set_unreachable(_, _), do: {:error, nil}
 
+  def get_consistently_unreachable do
+    reachability_datetime_threshold = Instances.reachability_datetime_threshold()
+
+    from(i in Instance,
+      where: ^reachability_datetime_threshold > i.unreachable_since,
+      order_by: i.unreachable_since,
+      select: {i.host, i.unreachable_since}
+    )
+    |> Repo.all()
+  end
+
   defp parse_datetime(datetime) when is_binary(datetime) do
     NaiveDateTime.from_iso8601(datetime)
   end

lib/pleroma/web/pleroma_api/controllers/instances_controller.ex

@@ -0,0 +1,19 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2020 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.Web.PleromaAPI.InstancesController do
+  use Pleroma.Web, :controller
+
+  alias Pleroma.Instances
+
+  # defdelegate open_api_operation(action), to: Pleroma.Web.ApiSpec.PleromaInstancesController
+
+  def show(conn, _params) do
+    unreachable =
+      Instances.get_consistently_unreachable()
+      |> Enum.reduce(%{}, fn {host, date}, acc -> Map.put(acc, host, to_string(date)) end)
+
+    json(conn, %{"unreachable" => unreachable})
+  end
+end

lib/pleroma/web/router.ex

@@ -373,6 +373,7 @@ defmodule Pleroma.Web.Router do
   scope "/api/v1/pleroma", Pleroma.Web.PleromaAPI do
     pipe_through(:api)
     get("/accounts/:id/scrobbles", ScrobbleController, :index)
+    get("/federation_status", InstancesController, :show)
   end
 
   scope "/api/v1", Pleroma.Web.MastodonAPI do