Allow Logger backend to use Sentry metadata (#712)

Closes #710.

Author: whatyouhide

lib/sentry/context.ex

@@ -143,14 +143,20 @@ defmodule Sentry.Context do
   @typedoc since: "9.0.0"
   @type extra() :: %{optional(atom()) => term()}
 
-  @logger_metadata_key :sentry
+  @logger_metadata_key :__sentry__
   @user_key :user
   @tags_key :tags
   @extra_key :extra
   @request_key :request
   @breadcrumbs_key :breadcrumbs
   @attachments_key :attachments
 
+  @doc false
+  @spec __logger_metadata_key__() :: unquote(@logger_metadata_key)
+  def __logger_metadata_key__ do
+    @logger_metadata_key
+  end
+
   @doc """
   Retrieves all currently-set context on the current process.
 

lib/sentry/logger_backend.ex

@@ -55,6 +55,7 @@ defmodule Sentry.LoggerBackend do
 
   @behaviour :gen_event
 
+  alias Sentry.Context
   alias Sentry.LoggerUtils
 
   ## State
@@ -122,17 +123,21 @@ defmodule Sentry.LoggerBackend do
   ## Helpers
 
   defp log(level, msg, meta, state) do
+    sentry_context_from_meta = meta[:sentry]
+    sentry_context_from_sentry = meta[Context.__logger_metadata_key__()]
+
+    sentry_context =
+      if sentry_context_from_meta || sentry_context_from_sentry do
+        Map.merge(sentry_context_from_meta || %{}, sentry_context_from_sentry || %{})
+      else
+        nil
+      end
+
     # Logger backends run in their own process, that's why we read the context from meta[:sentry].
     # 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 = meta[:sentry],
-        Map.new(meta),
-        state.metadata
-      )
+    opts = LoggerUtils.build_sentry_options(level, sentry_context, Map.new(meta), state.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

@@ -150,7 +150,14 @@ defmodule Sentry.LoggerHandler do
         # If we take meta[:sentry] here, we would duplicate all the stuff. This
         # behavior is different than the one in Sentry.LoggerBackend because the Logger
         # backend runs in its own process.
-        sentry_opts = LoggerUtils.build_sentry_options(log_level, nil, log_meta, config.metadata)
+        sentry_opts =
+          LoggerUtils.build_sentry_options(
+            log_level,
+            log_meta[:sentry],
+            log_meta,
+            config.metadata
+          )
+
         log_unfiltered(log_event, sentry_opts, config)
     end
   end

lib/sentry/logger_utils.ex

@@ -46,9 +46,11 @@ defmodule Sentry.LoggerUtils do
   end
 
   defp get_sentry_options_from_callers([caller | rest]) when is_pid(caller) do
+    logger_metadata_key = Sentry.Context.__logger_metadata_key__()
+
     with {:current_node, true} <- {:current_node, node(caller) == Node.self()},
          {:dictionary, [_ | _] = dictionary} <- :erlang.process_info(caller, :dictionary),
-         %{sentry: sentry} <- dictionary[:"$logger_metadata$"] do
+         %{^logger_metadata_key => sentry} <- dictionary[:"$logger_metadata$"] do
       sentry
     else
       _ -> get_sentry_options_from_callers(rest)