feat: provide metrics endpoint (#3902)

* feat: provide metrics endpoint

* config

* enable otel metrics by default

Co-authored-by: Florian Forster <florian@caos.ch>

internal/telemetry/otel/resource.go

@@ -0,0 +1,25 @@
+package otel
+
+import (
+	"go.opentelemetry.io/otel/attribute"
+	"go.opentelemetry.io/otel/sdk/resource"
+	semconv "go.opentelemetry.io/otel/semconv/v1.7.0"
+
+	"github.com/zitadel/zitadel/cmd/build"
+)
+
+func ResourceWithService() (*resource.Resource, error) {
+	attributes := []attribute.KeyValue{
+		semconv.ServiceNameKey.String("ZITADEL"),
+	}
+	if build.Version() != "" {
+		attributes = append(attributes, semconv.ServiceVersionKey.String(build.Version()))
+	}
+	return resource.Merge(
+		resource.Default(),
+		resource.NewWithAttributes(
+			semconv.SchemaURL,
+			attributes...,
+		),
+	)
+}