From 207532fe977d02dec7aca226d8746b76ad093ec0 Mon Sep 17 00:00:00 2001
From: DarthSim <darthsim@gmail.com>
Date: Sun, 21 Sep 2025 21:15:46 +0300
Subject: [PATCH] Format New Relic and OpenTelemetry metadata values that
 implement the `fmt.Stringer` interface as strings

---
 CHANGELOG.md                 | 4 ++++
 metrics/newrelic/newrelic.go | 5 +++++
 metrics/otel/otel.go         | 5 +++++
 3 files changed, 14 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 3134be55..31070523 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,9 @@
 # Changelog
 
+## [Unreleased]
+### Changed
+- Format New Relic and OpenTelemetry metadata values that implement the `fmt.Stringer` interface as strings.
+
 ## [3.30.0] - 2025-09-17
 ### Added
 - Add [IMGPROXY_GRACEFUL_STOP_TIMEOUT](https://docs.imgproxy.net/latest/configuration/options#IMGPROXY_GRACEFUL_STOP_TIMEOUT) config.
diff --git a/metrics/newrelic/newrelic.go b/metrics/newrelic/newrelic.go
index 9edfb950..14a41ca6 100644
--- a/metrics/newrelic/newrelic.go
+++ b/metrics/newrelic/newrelic.go
@@ -141,6 +141,11 @@ func setMetadata(span attributable, key string, value interface{}) {
 		return
 	}
 
+	if stringer, ok := value.(fmt.Stringer); ok {
+		span.AddAttribute(key, stringer.String())
+		return
+	}
+
 	rv := reflect.ValueOf(value)
 	switch {
 	case rv.Kind() == reflect.String || rv.Kind() == reflect.Bool:
diff --git a/metrics/otel/otel.go b/metrics/otel/otel.go
index 7514cc93..1f153c17 100644
--- a/metrics/otel/otel.go
+++ b/metrics/otel/otel.go
@@ -431,6 +431,11 @@ func setMetadata(span trace.Span, key string, value interface{}) {
 		return
 	}
 
+	if stringer, ok := value.(fmt.Stringer); ok {
+		span.SetAttributes(attribute.String(key, stringer.String()))
+		return
+	}
+
 	rv := reflect.ValueOf(value)
 
 	switch {