From 4deca7769ef37fa99bf7a0cc0dd877aa0edad1db Mon Sep 17 00:00:00 2001
From: Ryan Lamb <4955475+kinyoklion@users.noreply.github.com>
Date: Wed, 18 Mar 2026 16:36:16 -0700
Subject: [PATCH 1/3] feat: Migrate from error_logger to OTP logger module

Replace all error_logger calls (info_msg, warning_msg, error_msg) with
their logger equivalents (logger:info, logger:warning, logger:error)
across 18 source files and 3 test files.

All logger calls include #{domain => [ldclient]} metadata, enabling
users to filter SDK logs using standard logger configuration. The logger
module also automatically attaches module, function, and line metadata.

This addresses GitHub issue #160. The error_logger module is marked for
eventual removal from OTP, and logger (available since OTP 21) is the
recommended replacement. All supported OTP versions (24+) include logger.

Migration notes for users:
- Users with custom error_logger report handlers that specifically
  capture SDK logs should switch to logger handlers instead. Example:

    logger:add_handler(my_handler, my_module, #{
        filter_default => stop,
        filters => [{ldclient_only,
            {fun logger_filters:domain/2, {log, sub, [ldclient]}}}]
    })

- Elixir users benefit automatically: SDK logs now appear as native
  Elixir Logger events with proper metadata instead of wrapped
  error_logger reports.
- No public API changes. This is an internal logging infrastructure
  change only.
---
 src/ldclient.erl                        |  2 +-
 src/ldclient_config.erl                 |  8 ++--
 src/ldclient_eval.erl                   | 24 +++++------
 src/ldclient_event_process_server.erl   |  4 +-
 src/ldclient_event_server.erl           |  6 +--
 src/ldclient_event_sup.erl              |  2 +-
 src/ldclient_instance_sup.erl           |  2 +-
 src/ldclient_rollout.erl                |  2 +-
 src/ldclient_storage_cache_server.erl   |  2 +-
 src/ldclient_storage_ets_server.erl     |  2 +-
 src/ldclient_storage_map_server.erl     |  2 +-
 src/ldclient_storage_redis_server.erl   | 22 +++++-----
 src/ldclient_testdata.erl               |  2 +-
 src/ldclient_update_file_server.erl     | 10 ++---
 src/ldclient_update_null_server.erl     |  4 +-
 src/ldclient_update_poll_server.erl     | 14 +++----
 src/ldclient_update_stream_server.erl   | 28 ++++++-------
 src/ldclient_update_testdata_server.erl |  4 +-
 test-tls/ldclient_tls_options_SUITE.erl |  4 +-
 test/ldclient_clause_SUITE.erl          |  6 +--
 test/ldclient_sdk_key_logging_SUITE.erl | 53 ++++++++-----------------
 21 files changed, 91 insertions(+), 112 deletions(-)

diff --git a/src/ldclient.erl b/src/ldclient.erl
index 1767536..47da641 100644
--- a/src/ldclient.erl
+++ b/src/ldclient.erl
@@ -283,7 +283,7 @@ ensure_context(#{kind := _Kind} = ContextOrContext) -> ContextOrContext;
 ensure_context(UserOrContext) ->
     case maps:is_key(key, UserOrContext) of
         %% We allow legacy users to have an empty key, but we log it.
-        false -> error_logger:warning_msg("Context key is blank. Flag evaluation will proceed, but the context will not be stored in Launchdarkly");
+        false -> logger:warning("Context key is blank. Flag evaluation will proceed, but the context will not be stored in Launchdarkly", #{domain => [ldclient]});
         true -> ok
     end,
     ldclient_context:new_from_user(UserOrContext).
diff --git a/src/ldclient_config.erl b/src/ldclient_config.erl
index 4a13de4..2298b49 100644
--- a/src/ldclient_config.erl
+++ b/src/ldclient_config.erl
@@ -388,8 +388,8 @@ set_valid_tag(Key, Value, MapOrUndefined) ->
                 false -> #{Key => Value}
             end;
         false ->
-            error_logger:warning_msg("The application ~p was invalid. Must only contain letters, numbers, ., _ or -,"
-            " be 64 characters or less, and cannot be an empty string.", [Key]),
+            logger:warning("The application ~p was invalid. Must only contain letters, numbers, ., _ or -,"
+            " be 64 characters or less, and cannot be an empty string.", [Key], #{domain => [ldclient]}),
             MapOrUndefined
     end.
 
@@ -445,10 +445,10 @@ tls_base_options() ->
 tls_basic_options(true) ->
     tls_basic_linux_options();
 tls_basic_options(false) ->
-    error_logger:warning_msg("TLS options are falling back to using the certifi store.
+    logger:warning("TLS options are falling back to using the certifi store.
     This means the OS certificate store was not in the default location (/etc/ssl/certs/ca-certificates.crt).
     Please specify a custom location. You can use tls_ca_certfile_options, or fully specify the tls_options.
-    You may see this warning in development on Mac/Windows."),
+    You may see this warning in development on Mac/Windows.", #{domain => [ldclient]}),
     tls_basic_certifi_options().
 
 -spec validate_tag_value(Value :: binary() | undefined) -> boolean().
diff --git a/src/ldclient_eval.erl b/src/ldclient_eval.erl
index 05d8ac0..9ea9e37 100644
--- a/src/ldclient_eval.erl
+++ b/src/ldclient_eval.erl
@@ -86,7 +86,7 @@ flag_key_for_context(_Tag, _FlagKey, _Context, DefaultValue, offline, _) ->
 flag_key_for_context(_Tag, _FlagKey, _Context, DefaultValue, _, not_initialized) ->
     {{null, DefaultValue, {error, client_not_ready}}, []};
 flag_key_for_context(Tag, FlagKey, Context, DefaultValue, online, store_initialized) ->
-    error_logger:warning_msg("Variation called before LaunchDarkly client initialization completed - using last known values from feature store."),
+    logger:warning("Variation called before LaunchDarkly client initialization completed - using last known values from feature store.", #{domain => [ldclient]}),
     FeatureStore = ldclient_config:get_value(Tag, feature_store),
     FlagRecs = FeatureStore:get(Tag, features, FlagKey),
     flag_recs_for_context(FlagKey, FlagRecs, Context, FeatureStore, Tag, DefaultValue);
@@ -145,7 +145,7 @@ all_flags_state(_Context, _Options, _Tag, offline, _) ->
 all_flags_state(_Context, _Options, _Tag, _, not_initialized) ->
     #{<<"$valid">> => false, <<"$flagsState">> => #{}};
 all_flags_state(Context, #{with_reasons := WithReason} = _Options, Tag, Offline, store_initialized) ->
-    error_logger:warning_msg("Called allFlagsState before client initialization; using last known values from data store."),
+    logger:warning("Called allFlagsState before client initialization; using last known values from data store.", #{domain => [ldclient]}),
     all_flags_state(Context, #{with_reasons := WithReason} = _Options, Tag, Offline, initialized);
 all_flags_state(Context, #{with_reasons := WithReason} = Options, Tag, _, initialized) ->
     FeatureStore = ldclient_config:get_value(Tag, feature_store),
@@ -246,7 +246,7 @@ all_flags_eval(_Context, _Tag, offline, _) ->
 all_flags_eval(_Context, _Tag, _, not_initialized) ->
     #{flag_values => #{}};
 all_flags_eval(Context, Tag, Offline, store_initialized) ->
-    error_logger:warning_msg("Called allFlagsState before client initialization; using last known values from data store."),
+    logger:warning("Called allFlagsState before client initialization; using last known values from data store.", #{domain => [ldclient]}),
     all_flags_eval(Context, Tag, Offline, initialized);
 all_flags_eval(Context, Tag, online, initialized) ->
     FeatureStore = ldclient_config:get_value(Tag, feature_store),
@@ -309,13 +309,13 @@ get_initialization_state(Tag, false) ->
 ) -> result().
 flag_recs_for_context(FlagKey, [], Context, _FeatureStore, _Tag, DefaultValue) ->
     % Flag not found
-    error_logger:warning_msg("Unknown feature flag ~p; returning default value", [FlagKey]),
+    logger:warning("Unknown feature flag ~p; returning default value", [FlagKey], #{domain => [ldclient]}),
     Reason = {error, flag_not_found},
     Events = [ldclient_event:new_for_unknown_flag(FlagKey, Context, DefaultValue, Reason)],
     {{null, DefaultValue, Reason}, Events};
 flag_recs_for_context(FlagKey, [{FlagKey, #{deleted := true}} | _], Context, _FeatureStore, _Tag, DefaultValue) ->
     % Flag found, but it's deleted
-    error_logger:warning_msg("Unknown feature flag ~p; returning default value", [FlagKey]),
+    logger:warning("Unknown feature flag ~p; returning default value", [FlagKey], #{domain => [ldclient]}),
     Reason = {error, flag_not_found},
     Events = [ldclient_event:new_for_unknown_flag(FlagKey, Context, DefaultValue, Reason)],
     {{null, DefaultValue, Reason}, Events};
@@ -394,8 +394,8 @@ check_prerequisites(
 ) ->
     case lists:member(PrerequisiteKey, VisitedFlags) of
         true ->
-            error_logger:error_msg("Prerequisite of ~p causing a circular reference."
-            " This is probably a temporary condition due to an incomplete update.", [FlagKey]),
+            logger:error("Prerequisite of ~p causing a circular reference."
+            " This is probably a temporary condition due to an incomplete update.", [FlagKey], #{domain => [ldclient]}),
             flag_for_context_prerequisites({malformed_flag, {error, malformed_flag}},
                 Flag, Context, FeatureStore, Tag, DefaultValue, Events);
         false ->
@@ -420,7 +420,7 @@ check_prerequisites(
 check_prerequisite_recs([], PrerequisiteKey, _Variation, _Prerequisites, #{key := FlagKey} = Flag,
     Context, FeatureStore, Tag, DefaultValue, Events, _VisitedFlags) ->
     % Short circuit if prerequisite flag is not found
-    error_logger:error_msg("Could not retrieve prerequisite flag ~p when evaluating ~p", [PrerequisiteKey, FlagKey]),
+    logger:error("Could not retrieve prerequisite flag ~p when evaluating ~p", [PrerequisiteKey, FlagKey], #{domain => [ldclient]}),
     flag_for_context_prerequisites({fail, {prerequisite_failed, [PrerequisiteKey]}}, Flag, Context,
         FeatureStore, Tag, DefaultValue, Events);
 check_prerequisite_recs([{PrerequisiteKey, PrerequisiteFlag} | _], PrerequisiteKey, Variation, Prerequisites, Flag,
@@ -526,7 +526,7 @@ check_rules([Rule | Rest], Flag, Context, FeatureStore, Tag, DefaultValue, Event
     check_rule_result({Result, Rule, Index}, Rest, Flag, Context, FeatureStore, Tag, DefaultValue, Events).
 
 check_rule_result({malformed_flag, _Rule, _Index}, _Rest, #{key := FlagKey} = _Flag, _Context, _FeatureStore, _Tag, DefaultValue, _Events) ->
-    error_logger:warning_msg("Data inconsistency in feature flag ~p: clause was malformed", [FlagKey]),
+    logger:warning("Data inconsistency in feature flag ~p: clause was malformed", [FlagKey], #{domain => [ldclient]}),
     Reason = {error, malformed_flag},
     {{null, DefaultValue, Reason}, []};
 check_rule_result({no_match, _Rule, Index}, Rest, Flag, Context, FeatureStore, Tag, DefaultValue, Events) ->
@@ -546,19 +546,19 @@ flag_for_context_variation_or_rollout(Variation, Reason, Flag, _Context, Default
 flag_for_context_variation_or_rollout(Rollout, Reason, #{key := FlagKey} = Flag, Context, DefaultValue, Events) when is_map(Rollout) ->
     case ldclient_rollout:rollout_context(Rollout, Flag, Context) of
         malformed_flag ->
-            error_logger:warning_msg("Data inconsistency in feature flag ~p: rollout was malformed", [FlagKey]),
+            logger:warning("Data inconsistency in feature flag ~p: rollout was malformed", [FlagKey], #{domain => [ldclient]}),
             {{null, DefaultValue, {error, malformed_flag}}, []};
         {Result, InExperiment} ->
             UpdatedReason = experimentize_reason(InExperiment, Reason),
             flag_for_context_rollout_result(Result, UpdatedReason, Flag, DefaultValue, Events)
     end;
 flag_for_context_variation_or_rollout(null, _Reason, #{key := FlagKey}, _Context, DefaultValue, Events) ->
-    error_logger:warning_msg("Data inconsistency in feature flag ~p: rule object with no variation or rollout", [FlagKey]),
+    logger:warning("Data inconsistency in feature flag ~p: rule object with no variation or rollout", [FlagKey], #{domain => [ldclient]}),
     Reason = {error, malformed_flag},
     {{null, DefaultValue, Reason}, Events}.
 
 flag_for_context_rollout_result(null, _Reason, #{key := FlagKey}, DefaultValue, Events) ->
-    error_logger:warning_msg("Data inconsistency in feature flag ~p: variation/rollout object with no variation or rollout", [FlagKey]),
+    logger:warning("Data inconsistency in feature flag ~p: variation/rollout object with no variation or rollout", [FlagKey], #{domain => [ldclient]}),
     Reason = {error, malformed_flag},
     {{null, DefaultValue, Reason}, Events};
 
diff --git a/src/ldclient_event_process_server.erl b/src/ldclient_event_process_server.erl
index bff2813..0ac76c4 100644
--- a/src/ldclient_event_process_server.erl
+++ b/src/ldclient_event_process_server.erl
@@ -70,7 +70,7 @@ get_last_server_time(Tag) ->
     {ok, Pid :: pid()} | ignore | {error, Reason :: term()}.
 start_link(Tag) ->
     ServerName = get_local_reg_name(Tag),
-    error_logger:info_msg("Starting event processor for ~p with name ~p", [Tag, ServerName]),
+    logger:info("Starting event processor for ~p with name ~p", [Tag, ServerName], #{domain => [ldclient]}),
     gen_server:start_link({local, ServerName}, ?MODULE, [Tag], []).
 
 -spec init(Args :: term()) ->
@@ -126,7 +126,7 @@ handle_cast({send_events, Events, SummaryEvent},
            erlang:send_after(1000, self(), {send, OutputEvents, PayloadId}),
            State;
        {error, permanent, Reason} ->
-           error_logger:error_msg("Permanent error sending events ~p", [Reason]),
+           logger:error("Permanent error sending events ~p", [Reason], #{domain => [ldclient]}),
            State
     end,
     {noreply, NewState};
diff --git a/src/ldclient_event_server.erl b/src/ldclient_event_server.erl
index 6253a9a..0c47091 100644
--- a/src/ldclient_event_server.erl
+++ b/src/ldclient_event_server.erl
@@ -94,7 +94,7 @@ flush(Tag) when is_atom(Tag) ->
     {ok, Pid :: pid()} | ignore | {error, Reason :: term()}.
 start_link(Tag) ->
     ServerName = get_local_reg_name(Tag),
-    error_logger:info_msg("Starting event storage server for ~p with name ~p", [Tag, ServerName]),
+    logger:info("Starting event storage server for ~p with name ~p", [Tag, ServerName], #{domain => [ldclient]}),
     gen_server:start_link({local, ServerName}, ?MODULE, [Tag], []).
 
 -spec init(Args :: term()) ->
@@ -152,7 +152,7 @@ handle_info(_Info, State) ->
 -spec terminate(Reason :: (normal | shutdown | {shutdown, term()} | term()),
     State :: state()) -> term().
 terminate(Reason, #{timer_ref := TimerRef} = _State) ->
-    error_logger:info_msg("Terminating event service, reason: ~p", [Reason]),
+    logger:info("Terminating event service, reason: ~p", [Reason], #{domain => [ldclient]}),
     _ = erlang:cancel_timer(TimerRef),
     ok;
 terminate(_Reason, _State) ->
@@ -195,7 +195,7 @@ add_event(Tag, #{type := custom, context := Context, timestamp := Timestamp} = E
 add_raw_event(Event, Events, Capacity) when length(Events) < Capacity ->
     [Event|Events];
 add_raw_event(_, Events, _) ->
-    error_logger:warning_msg("Exceeded event queue capacity. Increase capacity to avoid dropping events."),
+    logger:warning("Exceeded event queue capacity. Increase capacity to avoid dropping events.", #{domain => [ldclient]}),
     Events.
 
 -spec add_feature_request_event(ldclient_event:event(), summary_event()) ->
diff --git a/src/ldclient_event_sup.erl b/src/ldclient_event_sup.erl
index 642b48b..a154d5b 100644
--- a/src/ldclient_event_sup.erl
+++ b/src/ldclient_event_sup.erl
@@ -21,7 +21,7 @@
 -spec start_link(SupName :: atom(), Tag :: atom()) ->
     {ok, Pid :: pid()} | ignore | {error, Reason :: term()}.
 start_link(SupName, Tag) ->
-    error_logger:info_msg("Starting event supervisor for ~p with name ~p", [Tag, SupName]),
+    logger:info("Starting event supervisor for ~p with name ~p", [Tag, SupName], #{domain => [ldclient]}),
     supervisor:start_link({local, SupName}, ?MODULE, [Tag]).
 
 -spec init(Args :: term()) ->
diff --git a/src/ldclient_instance_sup.erl b/src/ldclient_instance_sup.erl
index 25b1be4..f244d6a 100644
--- a/src/ldclient_instance_sup.erl
+++ b/src/ldclient_instance_sup.erl
@@ -37,7 +37,7 @@ child_spec(Id, Args) ->
 ) ->
     {ok, Pid :: pid()} | ignore | {error, Reason :: term()}.
 start_link(SupName, UpdateSupName, UpdateWorkerModule, EventSupName, Tag) ->
-    error_logger:info_msg("Starting instance supervisor for ~p with name ~p", [Tag, SupName]),
+    logger:info("Starting instance supervisor for ~p with name ~p", [Tag, SupName], #{domain => [ldclient]}),
     supervisor:start_link({local, SupName}, ?MODULE, [UpdateSupName, UpdateWorkerModule, EventSupName, Tag]).
 
 -spec init(Args :: term()) ->
diff --git a/src/ldclient_rollout.erl b/src/ldclient_rollout.erl
index 135cc31..8f44c3b 100644
--- a/src/ldclient_rollout.erl
+++ b/src/ldclient_rollout.erl
@@ -63,7 +63,7 @@ parse_rollout_kind(<<"experiment">>) -> experiment;
 parse_rollout_kind(<<"rollout">>) -> rollout;
 parse_rollout_kind(Kind) ->
     %% If we are not familiar with this kind, then log it and default to rollout.
-    error_logger:warning_msg("Unrecognized rollout type: ~p", [Kind]),
+    logger:warning("Unrecognized rollout type: ~p", [Kind], #{domain => [ldclient]}),
     rollout.
 
 -spec rollout_context(
diff --git a/src/ldclient_storage_cache_server.erl b/src/ldclient_storage_cache_server.erl
index 08405f2..6d73129 100644
--- a/src/ldclient_storage_cache_server.erl
+++ b/src/ldclient_storage_cache_server.erl
@@ -35,7 +35,7 @@
 %%===================================================================
 
 start_link(WorkerRegName, Tag) ->
-    error_logger:info_msg("Starting map server with name ~p", [WorkerRegName]),
+    logger:info("Starting map server with name ~p", [WorkerRegName], #{domain => [ldclient]}),
     gen_server:start_link({local, WorkerRegName}, ?MODULE, [Tag], []).
 
 init([Tag]) ->
diff --git a/src/ldclient_storage_ets_server.erl b/src/ldclient_storage_ets_server.erl
index 5ae22eb..8a59222 100644
--- a/src/ldclient_storage_ets_server.erl
+++ b/src/ldclient_storage_ets_server.erl
@@ -35,7 +35,7 @@
 %%===================================================================
 
 start_link(WorkerRegName, Tag) ->
-    error_logger:info_msg("Starting ets server with name ~p", [WorkerRegName]),
+    logger:info("Starting ets server with name ~p", [WorkerRegName], #{domain => [ldclient]}),
     gen_server:start_link({local, WorkerRegName}, ?MODULE, [Tag], []).
 
 init([Tag]) ->
diff --git a/src/ldclient_storage_map_server.erl b/src/ldclient_storage_map_server.erl
index 5ae7c10..e5d9d59 100644
--- a/src/ldclient_storage_map_server.erl
+++ b/src/ldclient_storage_map_server.erl
@@ -36,7 +36,7 @@
 %%===================================================================
 
 start_link(WorkerRegName, Tag) ->
-    error_logger:info_msg("Starting map server with name ~p", [WorkerRegName]),
+    logger:info("Starting map server with name ~p", [WorkerRegName], #{domain => [ldclient]}),
     gen_server:start_link({local, WorkerRegName}, ?MODULE, [Tag], []).
 
 init([Tag]) ->
diff --git a/src/ldclient_storage_redis_server.erl b/src/ldclient_storage_redis_server.erl
index 68b3479..7cd6943 100644
--- a/src/ldclient_storage_redis_server.erl
+++ b/src/ldclient_storage_redis_server.erl
@@ -45,7 +45,7 @@ tag => atom()
 %%===================================================================
 
 start_link(WorkerRegName, Tag) ->
-    error_logger:info_msg("Starting redis server with name ~p", [WorkerRegName]),
+    logger:info("Starting redis server with name ~p", [WorkerRegName], #{domain => [ldclient]}),
     gen_server:start_link({local, WorkerRegName}, ?MODULE, [Tag], []).
 
 -spec set_tls_options(Options :: list(), TlsOptions :: list()) -> OutOptions :: list().
@@ -211,7 +211,7 @@ create_bucket(false, Bucket, Client, Prefix, Buckets) ->
         {ok, _} ->
             {ok, [Bucket | Buckets]};
         {error, Reason} ->
-            error_logger:error_msg("Redis connection error during create_bucket for ~p: ~p", [Bucket, Reason]),
+            logger:error("Redis connection error during create_bucket for ~p: ~p", [Bucket, Reason], #{domain => [ldclient]}),
             {ok, [Bucket | Buckets]}
     end.
 
@@ -231,7 +231,7 @@ empty_bucket(true, Bucket, Client, Prefix) ->
             {ok, _} = create_bucket(false, Bucket, Client, Prefix, []),
             ok;
         {error, Reason} ->
-            error_logger:error_msg("Redis connection error during empty_bucket for ~p: ~p", [Bucket, Reason]),
+            logger:error("Redis connection error during empty_bucket for ~p: ~p", [Bucket, Reason], #{domain => [ldclient]}),
             ok
     end.
 
@@ -253,7 +253,7 @@ all_items(true, Bucket, Client, Prefix) ->
                 not lists:member(Elem, NullFilter) end, Values), %This removes the initial null key and value
             pairs(NewValues, Bucket);
         {error, Reason} ->
-            error_logger:error_msg("Redis error listing all items in bucket ~p: ~s", [Bucket, format_error(Reason)]),
+            logger:error("Redis error listing all items in bucket ~p: ~s", [Bucket, format_error(Reason)], #{domain => [ldclient]}),
             []
     end.
 
@@ -296,7 +296,7 @@ lookup_key(true, Key, Bucket, Client, Prefix) ->
                     end
             end;
         {error, Reason} ->
-            error_logger:error_msg("Redis error looking up key ~p in bucket ~p: ~s", [Key, Bucket, format_error(Reason)]),
+            logger:error("Redis error looking up key ~p in bucket ~p: ~s", [Key, Bucket, format_error(Reason)], #{domain => [ldclient]}),
             []
     end.
 
@@ -317,18 +317,18 @@ upsert_items(true, Items, Bucket, Client, Prefix) ->
                     case eredis:q(Client, ["HSET", bucket_name(Prefix, Bucket), K, jsx:encode(V)]) of
                         {ok, _} -> ok;
                         {error, Reason} ->
-                            error_logger:error_msg("Redis connection error during HSET for ~p key ~p: ~p", [Bucket, K, Reason]),
+                            logger:error("Redis connection error during HSET for ~p key ~p: ~p", [Bucket, K, Reason], #{domain => [ldclient]}),
                             ok
                     end
                 end, ok, Items),
             case eredis:q(Client, ["UNWATCH"]) of
                 {ok, <<"OK">>} -> Result;
                 {error, Reason} ->
-                    error_logger:error_msg("Redis connection error during UNWATCH for ~p: ~p", [Bucket, Reason]),
+                    logger:error("Redis connection error during UNWATCH for ~p: ~p", [Bucket, Reason], #{domain => [ldclient]}),
                     ok
             end;
         {error, Reason} ->
-            error_logger:error_msg("Redis connection error during WATCH for ~p: ~p", [Bucket, Reason]),
+            logger:error("Redis connection error during WATCH for ~p: ~p", [Bucket, Reason], #{domain => [ldclient]}),
             ok
     end.
 
@@ -360,7 +360,7 @@ delete_key(true, Key, Bucket, Client, Prefix) ->
     case eredis:q(Client, ["HDEL", bucket_name(Prefix, Bucket), Key]) of
         {ok, _} -> ok;
         {error, Reason} ->
-            error_logger:error_msg("Redis connection error during delete_key for ~p key ~p: ~p", [Bucket, Key, Reason]),
+            logger:error("Redis connection error during delete_key for ~p key ~p: ~p", [Bucket, Key, Reason], #{domain => [ldclient]}),
             ok
     end.
 
@@ -380,7 +380,7 @@ set_init(Client, Prefix) ->
     case eredis:q(Client, ["SET", lists:concat([Prefix, ":$inited"]), ""]) of
         {ok, _} -> ok;
         {error, Reason} ->
-            error_logger:error_msg("Redis connection error during set_init: ~p", [Reason]),
+            logger:error("Redis connection error during set_init: ~p", [Reason], #{domain => [ldclient]}),
             ok
     end.
 
@@ -393,6 +393,6 @@ get_init(Client, Prefix) ->
                 _ -> true
             end;
         {error, Reason} ->
-            error_logger:error_msg("Redis error getting init flag: ~s", [format_error(Reason)]),
+            logger:error("Redis error getting init flag: ~s", [format_error(Reason)], #{domain => [ldclient]}),
             false
     end.
diff --git a/src/ldclient_testdata.erl b/src/ldclient_testdata.erl
index f75271f..ea8c7d8 100644
--- a/src/ldclient_testdata.erl
+++ b/src/ldclient_testdata.erl
@@ -272,7 +272,7 @@ handle_info(_Info, State) ->
 -spec terminate(Reason :: (normal | shutdown | {shutdown, term()} | term()),
     State :: state()) -> term().
 terminate(Reason, _State) ->
-    error_logger:info_msg("Terminating, reason: ~p; Pid none~n", [Reason]),
+    logger:info("Terminating, reason: ~p; Pid none~n", [Reason], #{domain => [ldclient]}),
     ok.
 
 %% @doc
diff --git a/src/ldclient_update_file_server.erl b/src/ldclient_update_file_server.erl
index 97bc110..79415f4 100644
--- a/src/ldclient_update_file_server.erl
+++ b/src/ldclient_update_file_server.erl
@@ -38,7 +38,7 @@
 -spec start_link(Tag :: atom()) ->
     {ok, Pid :: pid()} | ignore | {error, Reason :: term()}.
 start_link(Tag) ->
-    error_logger:info_msg("Starting file update server for ~p", [Tag]),
+    logger:info("Starting file update server for ~p", [Tag], #{domain => [ldclient]}),
     gen_server:start_link(?MODULE, [Tag], []).
 
 -spec init(Args :: term()) ->
@@ -94,10 +94,10 @@ handle_info(_Info, State) ->
 -spec terminate(Reason :: (normal | shutdown | {shutdown, term()} | term()),
     State :: state()) -> term().
 terminate(Reason, #{timer_ref := undefined} = _State) ->
-    error_logger:info_msg("Terminating, reason: ~p; Pid none~n", [Reason]),
+    logger:info("Terminating, reason: ~p; Pid none~n", [Reason], #{domain => [ldclient]}),
     ok;
 terminate(Reason, #{timer_ref := TimerRef} = _State) ->
-    error_logger:info_msg("Terminating, reason: ~p; Pid none~n", [Reason]),
+    logger:info("Terminating, reason: ~p; Pid none~n", [Reason], #{domain => [ldclient]}),
     _ = timer:cancel(TimerRef),
     ok.
 
@@ -164,7 +164,7 @@ read_file(FilePath, ".json") ->
     {ok, Data} = file:read_file(FilePath),
     {ok, jsx:decode(Data, [return_maps])};
 read_file(FilePath, _Extension) ->
-    error_logger:warning_msg("File had unrecognized file extension. Valid extensions are .yaml and .json. File: ~p", [FilePath]),
+    logger:warning("File had unrecognized file extension. Valid extensions are .yaml and .json. File: ~p", [FilePath], #{domain => [ldclient]}),
     {error, #{}}.
 
 -spec try_read_file(FilePath :: string() | binary(), Extension :: string()) -> {ok | error, map()}.
@@ -172,7 +172,7 @@ try_read_file(FilePath, Extension) ->
     try
         read_file(FilePath, Extension)
     catch _:Exception:Stacktrace ->
-        error_logger:warning_msg("Problem reading file: ~p Exception: ~p ~p", [FilePath, Exception, Stacktrace]),
+        logger:warning("Problem reading file: ~p Exception: ~p ~p", [FilePath, Exception, Stacktrace], #{domain => [ldclient]}),
         {error, #{}}
     end.
 
diff --git a/src/ldclient_update_null_server.erl b/src/ldclient_update_null_server.erl
index 44304d4..7f4f4a7 100644
--- a/src/ldclient_update_null_server.erl
+++ b/src/ldclient_update_null_server.erl
@@ -30,7 +30,7 @@
 -spec start_link(Tag :: atom()) ->
     {ok, Pid :: pid()} | ignore | {error, Reason :: term()}.
 start_link(Tag) ->
-    error_logger:info_msg("Starting null update server for ~p", [Tag]),
+    logger:info("Starting null update server for ~p", [Tag], #{domain => [ldclient]}),
     gen_server:start_link(?MODULE, [Tag], []).
 
 -spec init(Args :: term()) ->
@@ -64,7 +64,7 @@ handle_info(_Info, State) ->
 -spec terminate(Reason :: (normal | shutdown | {shutdown, term()} | term()),
     State :: state()) -> term().
 terminate(Reason, _State) ->
-    error_logger:info_msg("Terminating, reason: ~p; Pid none~n", [Reason]),
+    logger:info("Terminating, reason: ~p; Pid none~n", [Reason], #{domain => [ldclient]}),
     ok.
 
 code_change(_OldVsn, State, _Extra) ->
diff --git a/src/ldclient_update_poll_server.erl b/src/ldclient_update_poll_server.erl
index 89ffaa5..59faf45 100644
--- a/src/ldclient_update_poll_server.erl
+++ b/src/ldclient_update_poll_server.erl
@@ -42,7 +42,7 @@
 -spec start_link(Tag :: atom()) ->
     {ok, Pid :: pid()} | ignore | {error, Reason :: term()}.
 start_link(Tag) ->
-    error_logger:info_msg("Starting polling update server for ~p", [Tag]),
+    logger:info("Starting polling update server for ~p", [Tag], #{domain => [ldclient]}),
     gen_server:start_link(?MODULE, [Tag], []).
 
 -spec init(Args :: term()) ->
@@ -98,7 +98,7 @@ handle_info(_Info, State) ->
 -spec terminate(Reason :: (normal | shutdown | {shutdown, term()} | term()),
     State :: state()) -> term().
 terminate(Reason, #{timer_ref := TimerRef} = _State) ->
-    error_logger:info_msg("Terminating polling, reason: ~p", [Reason]),
+    logger:info("Terminating polling, reason: ~p", [Reason], #{domain => [ldclient]}),
     _ = timer:cancel(TimerRef),
     ok;
 terminate(_Reason, _State) ->
@@ -133,16 +133,16 @@ poll(#{ feature_store := FeatureStore,
 
 -spec process_response(ldclient_update_requestor:response(), atom(), atom(), string()) -> ok.
 process_response({error, {bad_status, 401, _Reason}}, _, _, Uri) ->
-    error_logger:warning_msg("Invalid SDK key when when polling for updates at URL ~p. Verify that your SDK key is correct.", [Uri]),
+    logger:warning("Invalid SDK key when when polling for updates at URL ~p. Verify that your SDK key is correct.", [Uri], #{domain => [ldclient]}),
     ok;
 process_response({error, {bad_status, 404, _Reason}}, _, _, Uri) ->
-    error_logger:warning_msg("Resource not found when polling for updates at URL ~p.", [Uri]),
+    logger:warning("Resource not found when polling for updates at URL ~p.", [Uri], #{domain => [ldclient]}),
     ok;
 process_response({error, {bad_status, StatusCode, Reason}}, _, _, Uri) when StatusCode >= 300 ->
-    error_logger:warning_msg("Unexpected response code: ~p when polling for updates at URL ~p: ~p.", [StatusCode, Uri, Reason]),
+    logger:warning("Unexpected response code: ~p when polling for updates at URL ~p: ~p.", [StatusCode, Uri, Reason], #{domain => [ldclient]}),
     ok;
 process_response({error, network_error}, _, _, Uri) ->
-    error_logger:warning_msg("Failed to connect to update server at: %p", [Uri]),
+    logger:warning("Failed to connect to update server at: %p", [Uri], #{domain => [ldclient]}),
     ok;
 process_response({ok, not_modified}, _, _, _) -> ok;
 process_response({ok, ResponseBody}, FeatureStore, Tag, _) ->
@@ -157,7 +157,7 @@ process_response({ok, ResponseBody}, FeatureStore, Tag, _) ->
 process_response_body(ResponseBody, ldclient_storage_redis, Tag) ->
     Data = jsx:decode(ResponseBody, [return_maps]),
     [Flags, Segments] = get_put_items(Data),
-    error_logger:info_msg("Received poll event with ~p flags and ~p segments", [maps:size(Flags), maps:size(Segments)]),
+    logger:info("Received poll event with ~p flags and ~p segments", [maps:size(Flags), maps:size(Segments)], #{domain => [ldclient]}),
     ok = ldclient_storage_redis:upsert_clean(Tag, features, Flags),
     ok = ldclient_storage_redis:upsert_clean(Tag, segments, Segments),
     ok = ldclient_storage_redis:set_init(Tag);
diff --git a/src/ldclient_update_stream_server.erl b/src/ldclient_update_stream_server.erl
index 5902eb4..8bc061e 100644
--- a/src/ldclient_update_stream_server.erl
+++ b/src/ldclient_update_stream_server.erl
@@ -42,7 +42,7 @@
 -spec start_link(Tag :: atom()) ->
     {ok, Pid :: pid()} | ignore | {error, Reason :: term()}.
 start_link(Tag) ->
-    error_logger:info_msg("Starting streaming update server for ~p", [Tag]),
+    logger:info("Starting streaming update server for ~p", [Tag], #{domain => [ldclient]}),
     gen_server:start_link(?MODULE, [Tag], []).
 
 -spec init(Args :: term()) ->
@@ -86,7 +86,7 @@ handle_cast(_Request, State) ->
     {noreply, State}.
 
 handle_info({listen}, #{stream_uri := Uri} = State) ->
-    error_logger:info_msg("Starting streaming connection to URL: ~p", [Uri]),
+    logger:info("Starting streaming connection to URL: ~p", [Uri], #{domain => [ldclient]}),
     NewState = do_listen(State),
     {noreply, NewState};
 handle_info({'DOWN', _Mref, process, ShotgunPid, Reason}, #{conn := ShotgunPid, backoff := Backoff} = State) ->
@@ -94,10 +94,10 @@ handle_info({'DOWN', _Mref, process, ShotgunPid, Reason}, #{conn := ShotgunPid,
     _ = ldclient_backoff:fire(NewBackoff),
     % Reason from DOWN message could contain connection details with headers/SDK keys
     SafeReason = ldclient_key_redaction:format_shotgun_error(Reason),
-    error_logger:warning_msg("Got DOWN message from shotgun pid with reason: ~s, will retry in ~p ms~n", [SafeReason, maps:get(current, NewBackoff)]),
+    logger:warning("Got DOWN message from shotgun pid with reason: ~s, will retry in ~p ms~n", [SafeReason, maps:get(current, NewBackoff)], #{domain => [ldclient]}),
     {noreply, State#{conn := undefined, backoff := NewBackoff}};
 handle_info({timeout, _TimerRef, listen}, State) ->
-    error_logger:info_msg("Reconnecting streaming connection...~n"),
+    logger:info("Reconnecting streaming connection...~n", #{domain => [ldclient]}),
     NewState = do_listen(State),
     {noreply, NewState};
 handle_info(_Info, State) ->
@@ -106,10 +106,10 @@ handle_info(_Info, State) ->
 -spec terminate(Reason :: (normal | shutdown | {shutdown, term()} | term()),
     State :: state()) -> term().
 terminate(Reason, #{conn := undefined} = _State) ->
-    error_logger:info_msg("Terminating, reason: ~p; Pid none~n", [Reason]),
+    logger:info("Terminating, reason: ~p; Pid none~n", [Reason], #{domain => [ldclient]}),
     ok;
 terminate(Reason, #{conn := ShotgunPid} = _State) ->
-    error_logger:info_msg("Terminating streaming connection, reason: ~p; Pid ~p~n", [Reason, ShotgunPid]),
+    logger:info("Terminating streaming connection, reason: ~p; Pid ~p~n", [Reason, ShotgunPid], #{domain => [ldclient]}),
     ok = shotgun:close(ShotgunPid).
 
 code_change(_OldVsn, State, _Extra) ->
@@ -136,7 +136,7 @@ do_listen(#{
         {error, permanent, Reason} ->
             % Reason here is already safe: either a sanitized string from format_shotgun_error
             % or an integer status code from the do_listen/5 method.
-            error_logger:error_msg("Stream encountered permanent error ~p, giving up~n", [Reason]),
+            logger:error("Stream encountered permanent error ~p, giving up~n", [Reason], #{domain => [ldclient]}),
             State;
         {ok, Pid} ->
             NewBackoff = ldclient_backoff:succeed(Backoff),
@@ -154,7 +154,7 @@ do_listen(#{
 -spec do_listen_fail_backoff(ldclient_backoff:backoff(), atom(), term()) -> ldclient_backoff:backoff().
 do_listen_fail_backoff(Backoff, Code, Reason) ->
     NewBackoff = ldclient_backoff:fail(Backoff),
-    error_logger:warning_msg("Error establishing streaming connection (~p): ~p, will retry in ~p ms", [Code, Reason, maps:get(current, NewBackoff)]),
+    logger:warning("Error establishing streaming connection (~p): ~p, will retry in ~p ms", [Code, Reason, maps:get(current, NewBackoff)], #{domain => [ldclient]}),
     _ = ldclient_backoff:fire(NewBackoff),
     NewBackoff.
 
@@ -179,12 +179,12 @@ do_listen(Uri, FeatureStore, Tag, GunOpts, Headers) ->
                     catch Code:_Reason ->
                         % Exception when processing event - don't log exception details
                         % as they could theoretically contain sensitive data
-                        error_logger:warning_msg("Invalid SSE event error (~p)", [Code]),
+                        logger:warning("Invalid SSE event error (~p)", [Code], #{domain => [ldclient]}),
                         shotgun:close(Pid)
                     end;
                 (fin, _Ref, _Bin) ->
                     % Connection ended, close monitored shotgun client pid, so we can reconnect
-                    error_logger:warning_msg("Streaming connection ended"),
+                    logger:warning("Streaming connection ended", #{domain => [ldclient]}),
                     shotgun:close(Pid)
                 end,
             Options = #{async => true, async_mode => sse, handle_event => F, allow_reconnect => false},
@@ -234,13 +234,13 @@ decode_data(_, Data) -> jsx:decode(Data, [return_maps]).
 -spec process_items(EventOperation :: ldclient_storage_engine:event_operation(), Data :: map(), FeatureStore :: atom(), Tag :: atom()) -> ok.
 process_items(put, Data, ldclient_storage_redis, Tag) ->
     [Flags, Segments] = get_put_items(Data),
-    error_logger:info_msg("Received stream event with ~p flags and ~p segments", [maps:size(Flags), maps:size(Segments)]),
+    logger:info("Received stream event with ~p flags and ~p segments", [maps:size(Flags), maps:size(Segments)], #{domain => [ldclient]}),
     ok = ldclient_storage_redis:upsert_clean(Tag, features, Flags),
     ok = ldclient_storage_redis:upsert_clean(Tag, segments, Segments),
     ok = ldclient_storage_redis:set_init(Tag);
 process_items(put, Data, FeatureStore, Tag) ->
     [Flags, Segments] = get_put_items(Data),
-    error_logger:info_msg("Received event with ~p flags and ~p segments", [maps:size(Flags), maps:size(Segments)]),
+    logger:info("Received event with ~p flags and ~p segments", [maps:size(Flags), maps:size(Segments)], #{domain => [ldclient]}),
     ParsedFlags = maps:map(
         fun(_K, V) -> ldclient_flag:new(V) end
         , Flags),
@@ -255,7 +255,7 @@ process_items(patch, Data, FeatureStore, Tag) ->
             ok = maybe_patch_item(FeatureStore, Tag, Bucket, Key, Item, ParseFunction);
         error ->
             #{<<"path">> := Path} = Data,
-            error_logger:warning_msg("Unrecognized patch path ~p", [Path]),
+            logger:warning("Unrecognized patch path ~p", [Path], #{domain => [ldclient]}),
             ok
     end;
 process_items(delete, Data, FeatureStore, Tag) ->
@@ -281,7 +281,7 @@ delete_items(#{<<"path">> := <<"/flags/",Key/binary>>, <<"version">> := Version}
 delete_items(#{<<"path">> := <<"/segments/",Key/binary>>, <<"version">> := Version}, FeatureStore, Tag) ->
     ok = maybe_delete_item(FeatureStore, Tag, segments, Key, Version);
 delete_items(_Path, _FeatureStore, _Tag) ->
-    error_logger:error_msg("Invalid delete path").
+    logger:error("Invalid delete path", #{domain => [ldclient]}).
 
 -spec maybe_patch_item(atom(), atom(), atom(), binary(), map(), fun()) -> ok.
 maybe_patch_item(ldclient_storage_redis, Tag, Bucket, Key, Item, _ParseFunction) ->
diff --git a/src/ldclient_update_testdata_server.erl b/src/ldclient_update_testdata_server.erl
index fc8c18a..de8e2c7 100644
--- a/src/ldclient_update_testdata_server.erl
+++ b/src/ldclient_update_testdata_server.erl
@@ -33,7 +33,7 @@
 -spec start_link(Tag :: atom()) ->
     {ok, Pid :: pid()} | ignore | {error, Reason :: term()}.
 start_link(Tag) ->
-    error_logger:info_msg("Starting testdata update server for ~p", [Tag]),
+    logger:info("Starting testdata update server for ~p", [Tag], #{domain => [ldclient]}),
     gen_server:start_link(?MODULE, [Tag], []).
 
 -spec init(Args :: term()) ->
@@ -74,7 +74,7 @@ handle_info(_Info, State) ->
 -spec terminate(Reason :: (normal | shutdown | {shutdown, term()} | term()),
     State :: state()) -> term().
 terminate(Reason, #{ tag := Tag, test_data_server := TestDataServer }) ->
-    error_logger:info_msg("Terminating, reason: ~p; Pid: ~p ~n", [Reason, self()]),
+    logger:info("Terminating, reason: ~p; Pid: ~p ~n", [Reason, self()], #{domain => [ldclient]}),
     gen_server:call(TestDataServer, {unregister_instance, Tag}),
     ok.
 
diff --git a/test-tls/ldclient_tls_options_SUITE.erl b/test-tls/ldclient_tls_options_SUITE.erl
index b834ae5..15c4a6d 100644
--- a/test-tls/ldclient_tls_options_SUITE.erl
+++ b/test-tls/ldclient_tls_options_SUITE.erl
@@ -92,12 +92,12 @@ open_stream(Uri, HttpOptions, SdkKeyEnv) ->
                     shotgun:parse_event(Bin)
                 catch Code:Reason ->
                     % Exception when processing event, log error, close connection
-                    error_logger:warning_msg("Invalid SSE event error (~p): ~p", [Code, Reason]),
+                    logger:warning("Invalid SSE event error (~p): ~p", [Code, Reason], #{domain => [ldclient]}),
                     shotgun:close(Pid)
                 end;
                 (fin, _Ref, _Bin) ->
                     % Connection ended, close monitored shotgun client pid, so we can reconnect
-                    error_logger:warning_msg("Streaming connection ended"),
+                    logger:warning("Streaming connection ended", #{domain => [ldclient]}),
                     shotgun:close(Pid)
                 end,
             Options = #{async => true, async_mode => sse, handle_event => F},
diff --git a/test/ldclient_clause_SUITE.erl b/test/ldclient_clause_SUITE.erl
index b454289..8f86986 100644
--- a/test/ldclient_clause_SUITE.erl
+++ b/test/ldclient_clause_SUITE.erl
@@ -285,7 +285,7 @@ check_operators(_) ->
         true = case Result =:= ldclient_clause:match_context(Clause, Context, null, null) of
             true -> true;
             false ->
-                error_logger:error_msg("User context. Op ~p, ContextValue $p, ClauseValue ~p Expected ~p", [
+                logger:error("User context. Op ~p, ContextValue $p, ClauseValue ~p Expected ~p", [
                     Operator,
                     ContextValue,
                     ClauseValue,
@@ -308,7 +308,7 @@ check_operators(_) ->
         true = case Result =:= ldclient_clause:match_context(Clause, Context, null, null) of
                    true -> true;
                    false ->
-                       error_logger:error_msg("Non-user context. Op ~p, ContextValue $p, ClauseValue ~p Expected ~p", [
+                       logger:error("Non-user context. Op ~p, ContextValue $p, ClauseValue ~p Expected ~p", [
                            Operator,
                            ContextValue,
                            ClauseValue,
@@ -332,7 +332,7 @@ check_operators(_) ->
         true = case no_match =:= ldclient_clause:match_context(Clause, Context, null, null) of
                    true -> true;
                    false ->
-                       error_logger:error_msg("Mistmatched context kinds, should never match."
+                       logger:error("Mistmatched context kinds, should never match."
                        " Op ~p, ContextValue $p, ClauseValue ~p Expected ~p", [
                            Operator,
                            ContextValue,
diff --git a/test/ldclient_sdk_key_logging_SUITE.erl b/test/ldclient_sdk_key_logging_SUITE.erl
index 20df942..77f914a 100644
--- a/test/ldclient_sdk_key_logging_SUITE.erl
+++ b/test/ldclient_sdk_key_logging_SUITE.erl
@@ -17,6 +17,9 @@
     streaming_connection_error_does_not_log_sdk_key/1
 ]).
 
+%% logger handler callback
+-export([log/2]).
+
 %%====================================================================
 %% ct functions
 %%====================================================================
@@ -37,14 +40,14 @@ end_per_suite(_) ->
     ok = application:stop(ldclient).
 
 init_per_testcase(_, Config) ->
-    % Install a custom error_logger handler to capture logs
-    error_logger:tty(false),
-    error_logger:add_report_handler(?MODULE, self()),
+    % Install a custom logger handler to capture logs
+    HandlerId = ldclient_sdk_key_test_handler,
+    ok = logger:add_handler(HandlerId, ?MODULE, #{config => #{parent => self()}}),
     Config.
 
 end_per_testcase(_, _Config) ->
-    error_logger:delete_report_handler(?MODULE),
-    error_logger:tty(true),
+    HandlerId = ldclient_sdk_key_test_handler,
+    ok = logger:remove_handler(HandlerId),
     ok.
 
 %%====================================================================
@@ -178,38 +181,14 @@ flush_messages() ->
     end.
 
 %%====================================================================
-%% error_logger handler callbacks
+%% logger handler callback
 %%====================================================================
 
-init(Parent) ->
-    {ok, Parent}.
-
-handle_event({error, _GL, {_Pid, Format, Data}}, Parent) ->
-    Parent ! {error_log, Format, Data},
-    {ok, Parent};
-handle_event({error_report, _GL, {_Pid, _Type, Report}}, Parent) ->
-    Parent ! {error_report, Report},
-    {ok, Parent};
-handle_event({warning_msg, _GL, {_Pid, Format, Data}}, Parent) ->
-    Parent ! {warning_log, Format, Data},
-    {ok, Parent};
-handle_event({warning_report, _GL, {_Pid, _Type, Report}}, Parent) ->
-    Parent ! {warning_report, Report},
-    {ok, Parent};
-handle_event({info_msg, _GL, {_Pid, Format, Data}}, Parent) ->
-    Parent ! {info_log, Format, Data},
-    {ok, Parent};
-handle_event(_Event, Parent) ->
-    {ok, Parent}.
-
-handle_call(_Request, State) ->
-    {ok, ok, State}.
-
-handle_info(_Info, State) ->
-    {ok, State}.
-
-terminate(_Reason, _State) ->
+log(#{level := Level, msg := Msg}, #{config := #{parent := Parent}}) ->
+    FormattedMsg = case Msg of
+        {string, S} -> S;
+        {report, Report} -> io_lib:format("~p", [Report]);
+        {Format, Args} -> io_lib:format(Format, Args)
+    end,
+    Parent ! {log, Level, FormattedMsg},
     ok.
-
-code_change(_OldVsn, State, _Extra) ->
-    {ok, State}.

From 47e8a268dbce66e4d70e1d3abfe58315f5179a38 Mon Sep 17 00:00:00 2001
From: Ryan Lamb <4955475+kinyoklion@users.noreply.github.com>
Date: Wed, 18 Mar 2026 16:57:15 -0700
Subject: [PATCH 2/3] fix: Remove trailing ~n from logger format strings

The default logger_formatter templates already append newlines, so
trailing ~n in format strings produced double-newlines. Additionally,
one 2-argument logger:info call had ~n in a literal string where it
would not be expanded at all (unlike error_logger which processed all
strings through io_lib:format).
---
 src/ldclient_testdata.erl               |  2 +-
 src/ldclient_update_file_server.erl     |  4 ++--
 src/ldclient_update_null_server.erl     |  2 +-
 src/ldclient_update_stream_server.erl   | 10 +++++-----
 src/ldclient_update_testdata_server.erl |  2 +-
 5 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/src/ldclient_testdata.erl b/src/ldclient_testdata.erl
index ea8c7d8..50f9232 100644
--- a/src/ldclient_testdata.erl
+++ b/src/ldclient_testdata.erl
@@ -272,7 +272,7 @@ handle_info(_Info, State) ->
 -spec terminate(Reason :: (normal | shutdown | {shutdown, term()} | term()),
     State :: state()) -> term().
 terminate(Reason, _State) ->
-    logger:info("Terminating, reason: ~p; Pid none~n", [Reason], #{domain => [ldclient]}),
+    logger:info("Terminating, reason: ~p; Pid none", [Reason], #{domain => [ldclient]}),
     ok.
 
 %% @doc
diff --git a/src/ldclient_update_file_server.erl b/src/ldclient_update_file_server.erl
index 79415f4..911674e 100644
--- a/src/ldclient_update_file_server.erl
+++ b/src/ldclient_update_file_server.erl
@@ -94,10 +94,10 @@ handle_info(_Info, State) ->
 -spec terminate(Reason :: (normal | shutdown | {shutdown, term()} | term()),
     State :: state()) -> term().
 terminate(Reason, #{timer_ref := undefined} = _State) ->
-    logger:info("Terminating, reason: ~p; Pid none~n", [Reason], #{domain => [ldclient]}),
+    logger:info("Terminating, reason: ~p; Pid none", [Reason], #{domain => [ldclient]}),
     ok;
 terminate(Reason, #{timer_ref := TimerRef} = _State) ->
-    logger:info("Terminating, reason: ~p; Pid none~n", [Reason], #{domain => [ldclient]}),
+    logger:info("Terminating, reason: ~p; Pid none", [Reason], #{domain => [ldclient]}),
     _ = timer:cancel(TimerRef),
     ok.
 
diff --git a/src/ldclient_update_null_server.erl b/src/ldclient_update_null_server.erl
index 7f4f4a7..997f0ba 100644
--- a/src/ldclient_update_null_server.erl
+++ b/src/ldclient_update_null_server.erl
@@ -64,7 +64,7 @@ handle_info(_Info, State) ->
 -spec terminate(Reason :: (normal | shutdown | {shutdown, term()} | term()),
     State :: state()) -> term().
 terminate(Reason, _State) ->
-    logger:info("Terminating, reason: ~p; Pid none~n", [Reason], #{domain => [ldclient]}),
+    logger:info("Terminating, reason: ~p; Pid none", [Reason], #{domain => [ldclient]}),
     ok.
 
 code_change(_OldVsn, State, _Extra) ->
diff --git a/src/ldclient_update_stream_server.erl b/src/ldclient_update_stream_server.erl
index 8bc061e..a8cf5c5 100644
--- a/src/ldclient_update_stream_server.erl
+++ b/src/ldclient_update_stream_server.erl
@@ -94,10 +94,10 @@ handle_info({'DOWN', _Mref, process, ShotgunPid, Reason}, #{conn := ShotgunPid,
     _ = ldclient_backoff:fire(NewBackoff),
     % Reason from DOWN message could contain connection details with headers/SDK keys
     SafeReason = ldclient_key_redaction:format_shotgun_error(Reason),
-    logger:warning("Got DOWN message from shotgun pid with reason: ~s, will retry in ~p ms~n", [SafeReason, maps:get(current, NewBackoff)], #{domain => [ldclient]}),
+    logger:warning("Got DOWN message from shotgun pid with reason: ~s, will retry in ~p ms", [SafeReason, maps:get(current, NewBackoff)], #{domain => [ldclient]}),
     {noreply, State#{conn := undefined, backoff := NewBackoff}};
 handle_info({timeout, _TimerRef, listen}, State) ->
-    logger:info("Reconnecting streaming connection...~n", #{domain => [ldclient]}),
+    logger:info("Reconnecting streaming connection...", #{domain => [ldclient]}),
     NewState = do_listen(State),
     {noreply, NewState};
 handle_info(_Info, State) ->
@@ -106,10 +106,10 @@ handle_info(_Info, State) ->
 -spec terminate(Reason :: (normal | shutdown | {shutdown, term()} | term()),
     State :: state()) -> term().
 terminate(Reason, #{conn := undefined} = _State) ->
-    logger:info("Terminating, reason: ~p; Pid none~n", [Reason], #{domain => [ldclient]}),
+    logger:info("Terminating, reason: ~p; Pid none", [Reason], #{domain => [ldclient]}),
     ok;
 terminate(Reason, #{conn := ShotgunPid} = _State) ->
-    logger:info("Terminating streaming connection, reason: ~p; Pid ~p~n", [Reason, ShotgunPid], #{domain => [ldclient]}),
+    logger:info("Terminating streaming connection, reason: ~p; Pid ~p", [Reason, ShotgunPid], #{domain => [ldclient]}),
     ok = shotgun:close(ShotgunPid).
 
 code_change(_OldVsn, State, _Extra) ->
@@ -136,7 +136,7 @@ do_listen(#{
         {error, permanent, Reason} ->
             % Reason here is already safe: either a sanitized string from format_shotgun_error
             % or an integer status code from the do_listen/5 method.
-            logger:error("Stream encountered permanent error ~p, giving up~n", [Reason], #{domain => [ldclient]}),
+            logger:error("Stream encountered permanent error ~p, giving up", [Reason], #{domain => [ldclient]}),
             State;
         {ok, Pid} ->
             NewBackoff = ldclient_backoff:succeed(Backoff),
diff --git a/src/ldclient_update_testdata_server.erl b/src/ldclient_update_testdata_server.erl
index de8e2c7..d0e1afa 100644
--- a/src/ldclient_update_testdata_server.erl
+++ b/src/ldclient_update_testdata_server.erl
@@ -74,7 +74,7 @@ handle_info(_Info, State) ->
 -spec terminate(Reason :: (normal | shutdown | {shutdown, term()} | term()),
     State :: state()) -> term().
 terminate(Reason, #{ tag := Tag, test_data_server := TestDataServer }) ->
-    logger:info("Terminating, reason: ~p; Pid: ~p ~n", [Reason, self()], #{domain => [ldclient]}),
+    logger:info("Terminating, reason: ~p; Pid: ~p", [Reason, self()], #{domain => [ldclient]}),
     gen_server:call(TestDataServer, {unregister_instance, Tag}),
     ok.
 

From a7d7962370922b01af053b719052c51a4626c68c Mon Sep 17 00:00:00 2001
From: Ryan Lamb <4955475+kinyoklion@users.noreply.github.com>
Date: Thu, 19 Mar 2026 08:40:59 -0700
Subject: [PATCH 3/3] fix: Correct format specifier %p to ~p in poll server log

Pre-existing bug: the format string used C-style %p instead of Erlang's
~p for the Uri argument. This caused io_lib:format to fail at runtime,
silently losing the "Failed to connect to update server" warning message.
---
 src/ldclient_update_poll_server.erl | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/ldclient_update_poll_server.erl b/src/ldclient_update_poll_server.erl
index 59faf45..048436b 100644
--- a/src/ldclient_update_poll_server.erl
+++ b/src/ldclient_update_poll_server.erl
@@ -142,7 +142,7 @@ process_response({error, {bad_status, StatusCode, Reason}}, _, _, Uri) when Stat
     logger:warning("Unexpected response code: ~p when polling for updates at URL ~p: ~p.", [StatusCode, Uri, Reason], #{domain => [ldclient]}),
     ok;
 process_response({error, network_error}, _, _, Uri) ->
-    logger:warning("Failed to connect to update server at: %p", [Uri], #{domain => [ldclient]}),
+    logger:warning("Failed to connect to update server at: ~p", [Uri], #{domain => [ldclient]}),
     ok;
 process_response({ok, not_modified}, _, _, _) -> ok;
 process_response({ok, ResponseBody}, FeatureStore, Tag, _) ->