add metadata endpoint

backend/lib/backend/api.ex

@@ -108,6 +108,14 @@ defmodule Backend.Api do
     end
   end
 
+  def list_instance_types() do
+    Instance
+    |> select([i], i.type)
+    |> where([i], not is_nil(i.type))
+    |> distinct(true)
+    |> Repo.all()
+  end
+
   def search_instances(query, filters, from \\ 0) do
     page_size = 50
 

backend/lib/backend/util.ex

@@ -79,7 +79,6 @@ defmodule Backend.Util do
   @spec get_last_crawl(String.t()) :: Crawl.t() | nil
   def get_last_crawl(domain) do
     Crawl
-    |> select([c], c)
     |> where([c], c.instance_domain == ^domain)
     |> order_by(desc: :id)
     |> limit(1)

backend/lib/backend_web/controllers/metadata_controller.ex

@@ -0,0 +1,11 @@
+defmodule BackendWeb.MetadataController do
+  use BackendWeb, :controller
+  alias Backend.Api
+
+  action_fallback BackendWeb.FallbackController
+
+  def index(conn, _params) do
+    instance_types = Api.list_instance_types()
+    render(conn, "index.json", instance_types: instance_types)
+  end
+end

backend/lib/backend_web/router.ex

@@ -8,6 +8,7 @@ defmodule BackendWeb.Router do
   scope "/api", BackendWeb do
     pipe_through(:api)
 
+    resources("/metadata", MetadataController, only: [:index])
     resources("/instances", InstanceController, only: [:show])
     resources("/graph", GraphController, only: [:index, :show])
     resources("/search", SearchController, only: [:index])

backend/lib/backend_web/views/instance_view.ex

@@ -26,7 +26,12 @@ defmodule BackendWeb.InstanceView do
         }
 
       true ->
-        last_updated = max_datetime(crawl.inserted_at, instance.updated_at)
+        last_updated =
+          if crawl == nil do
+            instance.updated_at
+          else
+            max_datetime(crawl.inserted_at, instance.updated_at)
+          end
 
         filtered_peers =
           instance.peers

backend/lib/backend_web/views/metadata_view.ex

@@ -0,0 +1,9 @@
+defmodule BackendWeb.MetadataView do
+  use BackendWeb, :view
+
+  def render("index.json", %{instance_types: instance_types}) do
+    %{
+      instanceTypes: instance_types
+    }
+  end
+end