Add url.template attribute to otel4s-metrics-backend

Author: Remi Momprive

build.sbt

@@ -967,6 +967,7 @@ lazy val otel4sMetricsBackend = (projectMatrix in file("observability/otel4s-met
     libraryDependencies ++= Seq(
       "org.typelevel" %%% "otel4s-core-metrics" % otel4s,
       "org.typelevel" %%% "otel4s-semconv" % otel4s,
+      "org.typelevel" %%% "otel4s-semconv-experimental" % otel4s,
       "org.typelevel" %%% "otel4s-semconv-metrics-experimental" % otel4s % Test,
       "org.typelevel" %%% "otel4s-sdk-metrics-testkit" % otel4sSdk % Test
     )

observability/otel4s-metrics-backend/src/main/scala/sttp/client4/opentelemetry/otel4s/Otel4sMetricsBackend.scala

@@ -18,15 +18,18 @@ import org.typelevel.otel4s.semconv.attributes.{
   ServerAttributes,
   UrlAttributes
 }
+import org.typelevel.otel4s.semconv.experimental.attributes.UrlExperimentalAttributes
 import sttp.client4.listener.{ListenerBackend, RequestListener}
 import sttp.client4._
-import sttp.model.{HttpVersion, ResponseMetadata, StatusCode}
+import sttp.model.{HttpVersion, ResponseMetadata, StatusCode, Uri}
 import sttp.client4.wrappers.FollowRedirectsBackend
 
 import scala.concurrent.duration.FiniteDuration
 import scala.util.chaining._
 
 object Otel4sMetricsBackend {
+  private val IdPlaceholder = "{id}"
+  private val IdRegex = """[0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{12}|\d+""".r
 
   def apply[F[_]: Async: MeterProvider](
       delegate: Backend[F],
@@ -173,6 +176,7 @@ object Otel4sMetricsBackend {
       b ++= ServerAttributes.ServerAddress.maybe(request.uri.host)
       b ++= ServerAttributes.ServerPort.maybe(request.uri.port.map(_.toLong))
       b ++= UrlAttributes.UrlScheme.maybe(request.uri.scheme)
+      b ++= UrlExperimentalAttributes.UrlTemplate.maybe(urlTemplate(request))
 
       b.result()
     }
@@ -196,6 +200,7 @@ object Otel4sMetricsBackend {
       b ++= ServerAttributes.ServerPort.maybe(request.uri.port.map(_.toLong))
       b ++= NetworkAttributes.NetworkProtocolVersion.maybe(request.httpVersion.map(networkProtocol))
       b ++= UrlAttributes.UrlScheme.maybe(request.uri.scheme)
+      b ++= UrlExperimentalAttributes.UrlTemplate.maybe(urlTemplate(request))
 
       // response
       b ++= HttpAttributes.HttpResponseStatusCode.maybe(responseStatusCode.map(_.code.toLong))
@@ -211,6 +216,33 @@ object Otel4sMetricsBackend {
         case HttpVersion.HTTP_2   => "2"
         case HttpVersion.HTTP_3   => "3"
       }
+
+    private def urlTemplate(request: GenericRequest[_, _]): Option[String] = {
+      val rawSegments = request.uri.pathSegments.segments
+      val templatedSegments = rawSegments.map(s => if (IdRegex.matches(s.v)) IdPlaceholder else s.v)
+      val pathChanged = rawSegments.zip(templatedSegments).exists { case (s, t) => s.v != t }
+
+      val rawQueryParts = request.uri.querySegments.map {
+        case Uri.QuerySegment.KeyValue(k, v, _, _) => s"$k=$v"
+        case Uri.QuerySegment.Value(v, _)          => v
+        case Uri.QuerySegment.Plain(v, _)          => v
+      }
+      val templatedQueryParts = request.uri.querySegments.map {
+        case Uri.QuerySegment.KeyValue(k, v, _, _) =>
+          s"$k=${if (IdRegex.matches(v)) IdPlaceholder else v}"
+        case Uri.QuerySegment.Value(v, _) =>
+          if (IdRegex.matches(v)) IdPlaceholder else v
+        case Uri.QuerySegment.Plain(v, _) =>
+          IdRegex.replaceAllIn(v, IdPlaceholder)
+      }
+      val queryChanged = rawQueryParts != templatedQueryParts
+
+      if (pathChanged || queryChanged) {
+        val pathPart = "/" + templatedSegments.mkString("/")
+        val queryPart = if (templatedQueryParts.isEmpty) "" else "?" + templatedQueryParts.mkString("&")
+        Some(pathPart + queryPart)
+      } else None
+    }
   }
 
 }

observability/otel4s-metrics-backend/src/test/scala/sttp/client4/opentelemetry/otel4s/Otel4sMetricsBackendTest.scala

@@ -10,7 +10,6 @@ import org.typelevel.otel4s.metrics.MeterProvider
 import org.typelevel.otel4s.sdk.metrics.data.MetricData
 import org.typelevel.otel4s.sdk.testkit.metrics.MetricsTestkit
 import org.typelevel.otel4s.semconv.experimental.metrics.HttpExperimentalMetrics
-import org.typelevel.otel4s.semconv.metrics.HttpMetrics
 import org.typelevel.otel4s.semconv.{MetricSpec, Requirement}
 import sttp.model.{Header, StatusCode}
 import sttp.client4._
@@ -27,7 +26,7 @@ class Otel4sMetricsBackendTest extends AsyncFreeSpec with Matchers {
   "Otel4sMetricsBackend" - {
     "should pass the client semantic test" in {
       val specs = List(
-        HttpMetrics.ClientRequestDuration,
+        HttpExperimentalMetrics.ClientRequestDuration,
         HttpExperimentalMetrics.ClientRequestBodySize,
         HttpExperimentalMetrics.ClientResponseBodySize,
         HttpExperimentalMetrics.ClientActiveRequests