Add :tags_from_metadata option to Sentry.LoggerHandler (#840)

Adds a new option :tags_from_metadata that allows specifying sentry tags based on
already-set Logger metadata keys.

Co-authored-by: Andrea Leopardi <an.leopardi@gmail.com>

lib/sentry/logger_backend.ex

@@ -150,7 +150,14 @@ defmodule Sentry.LoggerBackend do
     # The context in the Logger backend process is not the same as the one in the process
     # that did the logging. This behavior is different than the one in Sentry.LoggerHandler,
     # since Logger handlers run in the caller process.
-    opts = LoggerUtils.build_sentry_options(level, sentry_context, Map.new(meta), state.metadata)
+    opts =
+      LoggerUtils.build_sentry_options(
+        level,
+        sentry_context,
+        Map.new(meta),
+        state.metadata,
+        _tags_from_metadata = []
+      )
 
     case meta[:crash_reason] do
       # If the crash reason is an exception, we want to report the exception itself

lib/sentry/logger_handler.ex

@@ -44,6 +44,14 @@ defmodule Sentry.LoggerHandler do
       If set to `:all`, all metadata will be included.
       """
     ],
+    tags_from_metadata: [
+      type: {:list, :atom},
+      default: [],
+      doc: """
+      Use this to include logger metadata as tags in reports. Metadata under the specified keys
+      in those keys will be added as tags to the event. *Available since v10.9.0*.
+      """
+    ],
     capture_log_messages: [
       type: :boolean,
       default: false,
@@ -220,6 +228,7 @@ defmodule Sentry.LoggerHandler do
     :level,
     :excluded_domains,
     :metadata,
+    :tags_from_metadata,
     :capture_log_messages,
     :rate_limiting,
     :sync_threshold
@@ -321,7 +330,8 @@ defmodule Sentry.LoggerHandler do
             log_level,
             log_meta[:sentry],
             log_meta,
-            config.metadata
+            config.metadata,
+            config.tags_from_metadata
           )
 
         log_unfiltered(log_event, sentry_opts, config)

lib/sentry/logger_utils.ex

@@ -10,18 +10,27 @@ defmodule Sentry.LoggerUtils do
 
   require Logger
 
-  @spec build_sentry_options(Logger.level(), keyword() | nil, map(), [atom()] | :all) ::
+  @spec build_sentry_options(
+          Logger.level(),
+          keyword() | nil,
+          map(),
+          [atom()] | :all,
+          [atom()]
+        ) ::
           keyword()
-  def build_sentry_options(level, sentry_context, meta, allowed_meta) do
+  def build_sentry_options(level, sentry_context, meta, allowed_meta, tags_from_metadata) do
     default_extra =
       Map.merge(
         %{logger_metadata: logger_metadata(meta, allowed_meta), logger_level: level},
         Map.take(meta, [:domain])
       )
 
+    default_tags = logger_tags_from_metadata(meta, tags_from_metadata)
+
     (sentry_context || get_sentry_options_from_callers(meta[:callers]) || %{})
     |> Map.new()
     |> Map.update(:extra, default_extra, &Map.merge(&1, default_extra))
+    |> Map.update(:tags, default_tags, &Map.merge(&1, default_tags))
     |> Map.merge(%{
       event_source: :logger,
       level: elixir_logger_level_to_sentry_level(level),
@@ -79,6 +88,15 @@ defmodule Sentry.LoggerUtils do
     :maps.map(fn _key, val -> attempt_to_convert_iodata(val) end, meta)
   end
 
+  defp logger_tags_from_metadata(meta, tags_from_metadata) do
+    for {key, value} <- meta,
+        key in tags_from_metadata,
+        is_binary(value),
+        into: %{} do
+      {key, value}
+    end
+  end
+
   defp attempt_to_convert_iodata(list) when is_list(list) do
     IO.chardata_to_string(list)
   rescue

test/sentry/logger_handler_test.exs

@@ -206,6 +206,35 @@ defmodule Sentry.LoggerHandlerTest do
     end
   end
 
+  describe "with logger metadata as tags" do
+    @tag handler_config: %{capture_log_messages: true, tags_from_metadata: [:string, :number]}
+    test "includes configured Logger metadata as tags, but only if strings", %{sender_ref: ref} do
+      Logger.metadata(string: "value", number: 42, other: "ignored")
+      Logger.error("Testing error")
+
+      assert_receive {^ref, event}
+      assert event.tags == %{string: "value"}
+    end
+
+    @tag handler_config: %{capture_log_messages: true, tags_from_metadata: []}
+    test "does not include Logger metadata as tags when disabled",
+         %{sender_ref: ref} do
+      Logger.error("Testing error", string: "value", number: 42)
+
+      assert_receive {^ref, event}
+      assert event.tags == %{}
+    end
+
+    @tag handler_config: %{capture_log_messages: true, tags_from_metadata: [:string, :number]}
+    test "merges configured tags with explicitly set tags", %{sender_ref: ref} do
+      Logger.metadata(string: "value", number: 42)
+      Logger.error("Testing error", sentry: [tags: %{explicit: "tag", number: 44}])
+
+      assert_receive {^ref, event}
+      assert event.tags == %{string: "value", number: 44, explicit: "tag"}
+    end
+  end
+
   describe "with a crashing GenServer" do
     setup do
       %{test_genserver: start_supervised!(TestGenServer, restart: :temporary)}