Add :ignore behavior for discovery events

lib/trento/discovery.ex

@@ -36,11 +36,7 @@ defmodule Trento.Discovery do
          :ok <- dispatch(commands) do
       :ok
     else
-      {:error, reason} = error ->
-        Logger.error("Failed to handle discovery event: #{inspect(reason)}")
-        store_discarded_discovery_event(event, inspect(reason))
-
-        error
+      result -> handle_not_dispatched(event, result)
     end
   end
 
@@ -164,24 +160,47 @@ defmodule Trento.Discovery do
   defp do_handle(_),
     do: {:error, :unknown_discovery_type}
 
-  @spec dispatch(command | [command]) :: :ok | {:error, any}
+  @spec dispatch(command | [command]) :: :ok | {:error, any} | {:ignore, any}
   defp dispatch(commands) when is_list(commands) do
     Enum.reduce(commands, :ok, fn command, acc ->
-      case {commanded().dispatch(command), acc} do
-        {:ok, :ok} ->
-          :ok
-
-        {{:error, error}, :ok} ->
-          {:error, [error]}
-
-        {{:error, error}, {:error, errors}} ->
-          {:error, [error | errors]}
-      end
+      result = commanded().dispatch(command)
+      aggregate_dispatch_results(acc, result)
     end)
   end
 
   defp dispatch(command), do: commanded().dispatch(command)
 
+  defp aggregate_dispatch_results(:ok, :ok), do: :ok
+  defp aggregate_dispatch_results(:ok, {:ignore, reason}), do: {:ignore, [reason]}
+  defp aggregate_dispatch_results(:ok, {:error, reason}), do: {:error, [reason]}
+  defp aggregate_dispatch_results({:ignore, reasons}, :ok), do: {:ignore, reasons}
+
+  defp aggregate_dispatch_results({:ignore, reasons}, {:ignore, reason}),
+    do: {:ignore, [reason | reasons]}
+
+  defp aggregate_dispatch_results({:ignore, reasons}, {:error, reason}),
+    do: {:error, [reason | reasons]}
+
+  defp aggregate_dispatch_results({:error, reasons}, :ok), do: {:errors, reasons}
+
+  defp aggregate_dispatch_results({:error, reasons}, {:ignore, reason}),
+    do: {:error, [reason | reasons]}
+
+  defp aggregate_dispatch_results({:error, reasons}, {:error, reason}),
+    do: {:error, [reason | reasons]}
+
   defp commanded,
     do: Application.fetch_env!(:trento, Trento.Commanded)[:adapter]
+
+  defp handle_not_dispatched(event, {:ignore, reasons}) do
+    Logger.warning("Ignored discovery event: #{inspect(reasons)}")
+    store_discarded_discovery_event(event, inspect(reasons))
+    :ok
+  end
+
+  defp handle_not_dispatched(event, {:error, reasons} = error) do
+    Logger.error("Failed to handle discovery event: #{inspect(reasons)}")
+    store_discarded_discovery_event(event, inspect(reasons))
+    error
+  end
 end

lib/trento/infrastructure/commanded/middleware/enrich.ex

@@ -26,6 +26,11 @@ defmodule Trento.Infrastructure.Commanded.Middleware.Enrich do
         pipeline
         |> respond({:error, reason})
         |> halt
+
+      {:ignore, reason} ->
+        pipeline
+        |> respond({:ignore, reason})
+        |> halt
     end
   end
 

lib/trento/infrastructure/commanded/middleware/enrich_register_application_instance.ex

@@ -36,7 +36,7 @@ defimpl Trento.Infrastructure.Commanded.Middleware.Enrichable,
          }}
 
       nil ->
-        {:error, :database_not_registered}
+        {:ignore, :database_not_registered}
     end
   end
 end

test/trento/infrastructure/commanded/middleware/enrich_register_application_instance_test.exs

@@ -68,7 +68,7 @@ defmodule Trento.Infrastructure.Commanded.Middleware.EnrichRegisterApplicationIn
         health: :passing
       )
 
-    assert {:error, :database_not_registered} = Enrichable.enrich(command, %{})
+    assert {:ignore, :database_not_registered} = Enrichable.enrich(command, %{})
   end
 
   test "should return an error if the database was not found" do
@@ -85,6 +85,6 @@ defmodule Trento.Infrastructure.Commanded.Middleware.EnrichRegisterApplicationIn
         health: :passing
       )
 
-    assert {:error, :database_not_registered} = Enrichable.enrich(command, %{})
+    assert {:ignore, :database_not_registered} = Enrichable.enrich(command, %{})
   end
 end

test/trento_web/controllers/v1/discovery_controller_test.exs

@@ -41,13 +41,13 @@ defmodule TrentoWeb.V1.DiscoveryControllerTest do
       |> json_response(202)
     end
 
-    test "collect action discards application instance registrations when the associated database does not exists",
+    test "collect action discards and store events when the command fails",
          %{conn: conn} do
       body =
         load_discovery_event_fixture("sap_system_discovery_application")
 
       expect(Trento.Commanded.Mock, :dispatch, fn _ ->
-        {:error, :any_error}
+        {:error, :any_reason}
       end)
 
       %{status: status} =
@@ -59,7 +59,29 @@ defmodule TrentoWeb.V1.DiscoveryControllerTest do
 
       [discarded_event] = Discovery.get_discarded_discovery_events(1)
 
-      assert %DiscardedDiscoveryEvent{payload: ^body, reason: "[:any_error]"} =
+      assert %DiscardedDiscoveryEvent{payload: ^body, reason: "[:any_reason]"} =
+               discarded_event
+    end
+
+    test "collect action discards and store events when the command is not dispatched",
+         %{conn: conn} do
+      body =
+        load_discovery_event_fixture("sap_system_discovery_application")
+
+      expect(Trento.Commanded.Mock, :dispatch, fn _ ->
+        {:ignore, :any_reason}
+      end)
+
+      %{status: status} =
+        conn
+        |> put_req_header("content-type", "application/json")
+        |> post("/api/v1/collect", body)
+
+      assert status == 202
+
+      [discarded_event] = Discovery.get_discarded_discovery_events(1)
+
+      assert %DiscardedDiscoveryEvent{payload: ^body, reason: "[:any_reason]"} =
                discarded_event
     end
   end