Accept keyword options in Sentry.add_logger_handler/1

.changeset/sentry-handler-opts.md

@@ -0,0 +1,5 @@
+---
+'@core/sync-service': patch
+---
+
+`Electric.Telemetry.Sentry.add_logger_handler/1` now accepts an optional second argument — a keyword list whose entries are merged into the `Sentry.LoggerHandler` config map — so downstream apps can tune handler settings like `:discard_threshold` and `:sync_threshold` without reaching into `:logger` after the fact. The existing single-arg `add_logger_handler(id)` form is preserved.

packages/sync-service/lib/electric/telemetry/sentry.ex

@@ -2,19 +2,29 @@ defmodule Electric.Telemetry.Sentry do
   use Electric.Telemetry
 
   @default_handler_id :electric_sentry_handler
+  @default_config %{metadata: :all, capture_log_messages: true, level: :error}
 
-  @spec add_logger_handler(handler_id :: atom()) :: :ok | {:error, term()}
+  @typedoc """
+  Extra entries for the `Sentry.LoggerHandler` config map (e.g.
+  `:discard_threshold`, `:sync_threshold`). Merged over the defaults at
+  install time.
+  """
+  @type handler_opts :: [{atom(), term()}]
+
+  def default_handler_id, do: @default_handler_id
+
+  @spec add_logger_handler(atom(), handler_opts()) :: :ok | {:error, term()}
+  @spec add_logger_handler(atom()) :: :ok | {:error, term()}
   @spec add_logger_handler() :: :ok | {:error, term()}
-  def add_logger_handler(id \\ @default_handler_id)
+  def add_logger_handler(id \\ @default_handler_id, opts \\ [])
 
   with_telemetry Sentry.LoggerHandler do
-    def add_logger_handler(id) do
-      :logger.add_handler(id, Sentry.LoggerHandler, %{
-        config: %{metadata: :all, capture_log_messages: true, level: :error}
-      })
+    def add_logger_handler(id, opts) do
+      config = Map.merge(@default_config, Map.new(opts))
+      :logger.add_handler(id, Sentry.LoggerHandler, %{config: config})
     end
   else
-    def add_logger_handler(_id), do: :ok
+    def add_logger_handler(_id, _opts), do: :ok
   end
 
   @spec set_tags_context(keyword()) :: :ok

packages/sync-service/test/electric/telemetry/sentry_test.exs

@@ -0,0 +1,66 @@
+if Electric.telemetry_enabled?() and Code.ensure_loaded?(Sentry.LoggerHandler) do
+  defmodule Electric.Telemetry.SentryTest do
+    # async: false because :logger handler state is VM-global — unique ids per
+    # test avoid name collisions but not the add/remove race across processes.
+    use ExUnit.Case, async: false
+
+    alias Electric.Telemetry.Sentry, as: ElectricSentry
+
+    setup do
+      id = :"sentry_test_#{System.unique_integer([:positive])}"
+      on_exit(fn -> _ = :logger.remove_handler(id) end)
+      {:ok, handler_id: id}
+    end
+
+    defp handler_config!(id) do
+      {:ok, %{config: config}} = :logger.get_handler_config(id)
+      config
+    end
+
+    describe "add_logger_handler/2" do
+      test "installs Sentry.LoggerHandler with default config", %{handler_id: id} do
+        assert :ok = ElectricSentry.add_logger_handler(id)
+
+        {:ok, handler} = :logger.get_handler_config(id)
+        assert handler.module == Sentry.LoggerHandler
+
+        assert %{metadata: :all, capture_log_messages: true, level: :error} =
+                 handler_config!(id)
+      end
+
+      test "merges caller-supplied options into the handler config",
+           %{handler_id: id} do
+        assert :ok =
+                 ElectricSentry.add_logger_handler(id,
+                   discard_threshold: 2000,
+                   sync_threshold: nil
+                 )
+
+        assert %{
+                 metadata: :all,
+                 capture_log_messages: true,
+                 level: :error,
+                 discard_threshold: 2000,
+                 sync_threshold: nil
+               } = handler_config!(id)
+      end
+
+      test "caller-supplied options override defaults", %{handler_id: id} do
+        assert :ok = ElectricSentry.add_logger_handler(id, level: :warning)
+
+        assert %{level: :warning} = handler_config!(id)
+      end
+
+      test "uses the default handler id when called with no arguments" do
+        default_id = ElectricSentry.default_handler_id()
+        _ = :logger.remove_handler(default_id)
+        on_exit(fn -> _ = :logger.remove_handler(default_id) end)
+
+        assert :ok = ElectricSentry.add_logger_handler()
+
+        {:ok, handler} = :logger.get_handler_config(default_id)
+        assert handler.module == Sentry.LoggerHandler
+      end
+    end
+  end
+end