Allow custom user-agent definition (#725)

* Allow custom user-agent definition

---------

Signed-off-by: Matthieu MOREL <matthieu.morel35@gmail.com>
Co-authored-by: Ben Kochie <superq@gmail.com>

version/info.go

@@ -90,8 +90,12 @@ func GetTags() string {
 	return computedTags
 }
 
-func UserAgent() string {
-	return "Prometheus/" + Version
+func PrometheusUserAgent() string {
+	return ComponentUserAgent("Prometheus")
+}
+
+func ComponentUserAgent(component string) string {
+	return component + "/" + Version
 }
 
 func init() {

version/info_test.go

@@ -0,0 +1,28 @@
+// Copyright 2024 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package version
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestPrometheusUserAgent(t *testing.T) {
+	require.Equal(t, "Prometheus/"+Version, PrometheusUserAgent())
+}
+
+func TestComponentUserAgent(t *testing.T) {
+	require.Equal(t, "Component/"+Version, ComponentUserAgent("Component"))
+}