From d4419995682532a83727b1cfda7a85b14148590e Mon Sep 17 00:00:00 2001
From: Vamshi Maskuri <117595548+varshith257@users.noreply.github.com>
Date: Sat, 26 Oct 2024 17:59:48 +0530
Subject: [PATCH 1/9] refactor: prometheus attributes format to otel attributes

---
 .../opentelemetry/OpenTelemetryMetrics.scala  | 32 +++++++++----
 .../OpenTelemetryMetricsTest.scala            | 46 +++++++++++--------
 2 files changed, 51 insertions(+), 27 deletions(-)

diff --git a/metrics/opentelemetry-metrics/src/main/scala/sttp/tapir/server/metrics/opentelemetry/OpenTelemetryMetrics.scala b/metrics/opentelemetry-metrics/src/main/scala/sttp/tapir/server/metrics/opentelemetry/OpenTelemetryMetrics.scala
index 9389c4c121..dfec33b98a 100644
--- a/metrics/opentelemetry-metrics/src/main/scala/sttp/tapir/server/metrics/opentelemetry/OpenTelemetryMetrics.scala
+++ b/metrics/opentelemetry-metrics/src/main/scala/sttp/tapir/server/metrics/opentelemetry/OpenTelemetryMetrics.scala
@@ -80,15 +80,28 @@ object OpenTelemetryMetrics {
   def requestActive[F[_]](meter: Meter, labels: MetricLabels): Metric[F, LongUpDownCounter] =
     Metric[F, LongUpDownCounter](
       meter
-        .upDownCounterBuilder("request_active")
+        .upDownCounterBuilder("http.server.active_requests")
         .setDescription("Active HTTP requests")
         .setUnit("1")
         .build(),
       onRequest = (req, counter, m) => {
         m.unit {
           EndpointMetric()
-            .onEndpointRequest { ep => m.eval(counter.add(1, asOpenTelemetryAttributes(labels, ep, req))) }
-            .onResponseBody { (ep, _) => m.eval(counter.add(-1, asOpenTelemetryAttributes(labels, ep, req))) }
+            .onEndpointRequest { ep =>
+              m.eval {
+                val attrs = asOpenTelemetryAttributes(labels, ep, req)
+                println(s"[DEBUG] Incrementing active requests with attributes: $attrs")
+
+                counter.add(1, attrs)
+              }
+            }
+            .onResponseBody { (ep, _) =>
+              m.eval {
+                val attrs = asOpenTelemetryAttributes(labels, ep, req)
+                println(s"[DEBUG] Decrementing active requests with attributes: $attrs")
+                counter.add(-1, attrs)
+              }
+            }
             .onException { (ep, _) => m.eval(counter.add(-1, asOpenTelemetryAttributes(labels, ep, req))) }
         }
       }
@@ -97,7 +110,7 @@ object OpenTelemetryMetrics {
   def requestTotal[F[_]](meter: Meter, labels: MetricLabels): Metric[F, LongCounter] =
     Metric[F, LongCounter](
       meter
-        .counterBuilder("request_total")
+        .counterBuilder("http.server.request.total")
         .setDescription("Total HTTP requests")
         .setUnit("1")
         .build(),
@@ -106,8 +119,11 @@ object OpenTelemetryMetrics {
           EndpointMetric()
             .onResponseBody { (ep, res) =>
               m.eval {
-                val otLabels =
+                val otLabels: Attributes =
                   merge(asOpenTelemetryAttributes(labels, ep, req), asOpenTelemetryAttributes(labels, Right(res), None))
+
+                println(s"[DEBUG] Incrementing total requests with labels: $otLabels")
+
                 counter.add(1, otLabels)
               }
             }
@@ -125,14 +141,14 @@ object OpenTelemetryMetrics {
   def requestDuration[F[_]](meter: Meter, labels: MetricLabels): Metric[F, DoubleHistogram] =
     Metric[F, DoubleHistogram](
       meter
-        .histogramBuilder("request_duration")
+        .histogramBuilder("http.server.request.duration")
         .setDescription("Duration of HTTP requests")
-        .setUnit("ms")
+        .setUnit("s")
         .build(),
       onRequest = (req, recorder, m) =>
         m.eval {
           val requestStart = Instant.now()
-          def duration = Duration.between(requestStart, Instant.now()).toMillis.toDouble
+          def duration = Duration.between(requestStart, Instant.now()).toMillis.toDouble / 1000.0
           EndpointMetric()
             .onResponseHeaders { (ep, res) =>
               m.eval {
diff --git a/metrics/opentelemetry-metrics/src/test/scala/sttp/tapir/server/metrics/opentelemetry/OpenTelemetryMetricsTest.scala b/metrics/opentelemetry-metrics/src/test/scala/sttp/tapir/server/metrics/opentelemetry/OpenTelemetryMetricsTest.scala
index fcc096a963..4581b09594 100644
--- a/metrics/opentelemetry-metrics/src/test/scala/sttp/tapir/server/metrics/opentelemetry/OpenTelemetryMetricsTest.scala
+++ b/metrics/opentelemetry-metrics/src/test/scala/sttp/tapir/server/metrics/opentelemetry/OpenTelemetryMetricsTest.scala
@@ -25,7 +25,7 @@ import scala.concurrent.Future
 
 class OpenTelemetryMetricsTest extends AnyFlatSpec with Matchers {
 
-  "default metrics" should "collect requests active" in {
+  "default metrics" should "collect http.server.active_requests" in {
     // given
     val reader = InMemoryMetricReader.create()
     val provider = SdkMeterProvider.builder().registerMetricReader(reader).build()
@@ -51,17 +51,27 @@ class OpenTelemetryMetricsTest extends AnyFlatSpec with Matchers {
 
     // then
     val point = longSumData(reader).head
-    point.getAttributes shouldBe Attributes.of(AttributeKey.stringKey("method"), "GET", AttributeKey.stringKey("path"), "/person")
+    point.getAttributes shouldBe Attributes.of(
+      AttributeKey.stringKey("http.request.method"),
+      "GET",
+      AttributeKey.stringKey("path"),
+      "/person"
+    )
     point.getValue shouldBe 1
 
     ScalaFutures.whenReady(response, Timeout(Span(3, Seconds))) { _ =>
       val point = longSumData(reader).head
-      point.getAttributes shouldBe Attributes.of(AttributeKey.stringKey("method"), "GET", AttributeKey.stringKey("path"), "/person")
+      point.getAttributes shouldBe Attributes.of(
+        AttributeKey.stringKey("http.request.method"),
+        "GET",
+        AttributeKey.stringKey("path"),
+        "/person"
+      )
       point.getValue shouldBe 0
     }
   }
 
-  "default metrics" should "collect requests total" in {
+  "default metrics" should "collect http.server.request.total" in {
     // given
     val reader = InMemoryMetricReader.create()
     val provider = SdkMeterProvider.builder().registerMetricReader(reader).build()
@@ -87,29 +97,29 @@ class OpenTelemetryMetricsTest extends AnyFlatSpec with Matchers {
       .count {
         case dp
             if dp.getAttributes == Attributes.of(
-              AttributeKey.stringKey("method"),
+              AttributeKey.stringKey("http.request.method"),
               "GET",
               AttributeKey.stringKey("path"),
               "/person",
-              AttributeKey.stringKey("status"),
-              "2xx"
+    AttributeKey.longKey("http.response.status_code").asInstanceOf[AttributeKey[Long]], // Explicitly cast to Long
+              200L
             ) && dp.getValue == 2 =>
           true
         case dp
             if dp.getAttributes == Attributes.of(
-              AttributeKey.stringKey("method"),
+              AttributeKey.stringKey("http.request.method"),
               "GET",
               AttributeKey.stringKey("path"),
               "/person",
-              AttributeKey.stringKey("status"),
-              "4xx"
+    AttributeKey.longKey("http.response.status_code").asInstanceOf[AttributeKey[Long]], // Explicitly cast to Long
+              400L
             ) && dp.getValue == 2 =>
           true
         case _ => false
       } shouldBe 2
   }
 
-  "default metrics" should "collect requests duration" in {
+  "default metrics" should "collect http.server.request.duration" in {
     // given
     val reader = InMemoryMetricReader.create()
     val provider = SdkMeterProvider.builder().registerMetricReader(reader).build()
@@ -140,14 +150,12 @@ class OpenTelemetryMetricsTest extends AnyFlatSpec with Matchers {
     val point = reader.collectAllMetrics().asScala.head.getHistogramData.getPoints.asScala
     point.map(_.getAttributes) should contain(
       Attributes.of(
-        AttributeKey.stringKey("method"),
+        AttributeKey.stringKey("http.request.method"),
         "GET",
         AttributeKey.stringKey("path"),
         "/person",
-        AttributeKey.stringKey("status"),
-        "2xx",
-        AttributeKey.stringKey("phase"),
-        "body"
+    AttributeKey.longKey("http.response.status_code").asInstanceOf[AttributeKey[Long]], // Explicitly cast to Long
+        200L
       )
     )
   }
@@ -197,12 +205,12 @@ class OpenTelemetryMetricsTest extends AnyFlatSpec with Matchers {
     // then
     val point = longSumData(reader).head
     point.getAttributes shouldBe Attributes.of(
-      AttributeKey.stringKey("method"),
+      AttributeKey.stringKey("http.request.method"),
       "GET",
       AttributeKey.stringKey("path"),
       "/person",
-      AttributeKey.stringKey("status"),
-      "5xx"
+    AttributeKey.longKey("http.response.status_code").asInstanceOf[AttributeKey[Long]], // Explicitly cast to Long
+      500L
     )
     point.getValue shouldBe 1
   }

From 657e1096511c081d2c41a0619027b99641aeeb2f Mon Sep 17 00:00:00 2001
From: Vamshi Maskuri <117595548+varshith257@users.noreply.github.com>
Date: Wed, 30 Oct 2024 17:47:52 +0530
Subject: [PATCH 2/9] Update OpenTelemetryMetrics.scala

---
 .../server/metrics/opentelemetry/OpenTelemetryMetrics.scala      | 1 +
 1 file changed, 1 insertion(+)

diff --git a/metrics/opentelemetry-metrics/src/main/scala/sttp/tapir/server/metrics/opentelemetry/OpenTelemetryMetrics.scala b/metrics/opentelemetry-metrics/src/main/scala/sttp/tapir/server/metrics/opentelemetry/OpenTelemetryMetrics.scala
index dfec33b98a..2e20fd48e1 100644
--- a/metrics/opentelemetry-metrics/src/main/scala/sttp/tapir/server/metrics/opentelemetry/OpenTelemetryMetrics.scala
+++ b/metrics/opentelemetry-metrics/src/main/scala/sttp/tapir/server/metrics/opentelemetry/OpenTelemetryMetrics.scala
@@ -138,6 +138,7 @@ object OpenTelemetryMetrics {
       }
     )
 
+  
   def requestDuration[F[_]](meter: Meter, labels: MetricLabels): Metric[F, DoubleHistogram] =
     Metric[F, DoubleHistogram](
       meter

From a6c7d6c78d4c297c448a70abfdaa2d6fdba6c7e2 Mon Sep 17 00:00:00 2001
From: Vamshi Maskuri <117595548+varshith257@users.noreply.github.com>
Date: Wed, 30 Oct 2024 22:50:43 +0530
Subject: [PATCH 3/9] refactor!: prometheus and OTEL defaul Metric formats

---
 .../opentelemetry/OpenTelemetryMetrics.scala  | 38 ++++++-------------
 .../OpenTelemetryMetricsTest.scala            | 18 +++++----
 .../sttp/tapir/server/metrics/Metric.scala    | 19 ++++++++++
 3 files changed, 40 insertions(+), 35 deletions(-)

diff --git a/metrics/opentelemetry-metrics/src/main/scala/sttp/tapir/server/metrics/opentelemetry/OpenTelemetryMetrics.scala b/metrics/opentelemetry-metrics/src/main/scala/sttp/tapir/server/metrics/opentelemetry/OpenTelemetryMetrics.scala
index 2e20fd48e1..d52368fd2e 100644
--- a/metrics/opentelemetry-metrics/src/main/scala/sttp/tapir/server/metrics/opentelemetry/OpenTelemetryMetrics.scala
+++ b/metrics/opentelemetry-metrics/src/main/scala/sttp/tapir/server/metrics/opentelemetry/OpenTelemetryMetrics.scala
@@ -7,7 +7,7 @@ import OpenTelemetryMetrics._
 import io.opentelemetry.api.OpenTelemetry
 import sttp.tapir.model.ServerRequest
 import sttp.tapir.server.interceptor.metrics.MetricsRequestInterceptor
-import sttp.tapir.server.metrics.{EndpointMetric, Metric, MetricLabels}
+import sttp.tapir.server.metrics.{EndpointMetric, Metric, MetricLabels, OTELMetricLabels}
 import sttp.tapir.server.model.ServerResponse
 
 import java.time.{Duration, Instant}
@@ -15,15 +15,15 @@ import java.time.{Duration, Instant}
 case class OpenTelemetryMetrics[F[_]](meter: Meter, metrics: List[Metric[F, _]]) {
 
   /** Registers a `request_active{path, method}` up-down-counter (assuming default labels). */
-  def addRequestsActive(labels: MetricLabels = MetricLabels.Default): OpenTelemetryMetrics[F] =
+  def addRequestsActive(labels: MetricLabels = OTELMetricLabels.Default): OpenTelemetryMetrics[F] =
     copy(metrics = metrics :+ requestActive(meter, labels))
 
   /** Registers a `request_total{path, method, status}` counter (assuming default labels). */
-  def addRequestsTotal(labels: MetricLabels = MetricLabels.Default): OpenTelemetryMetrics[F] =
+  def addRequestsTotal(labels: MetricLabels = OTELMetricLabels.Default): OpenTelemetryMetrics[F] =
     copy(metrics = metrics :+ requestTotal(meter, labels))
 
   /** Registers a `request_duration_seconds{path, method, status, phase}` histogram (assuming default labels). */
-  def addRequestsDuration(labels: MetricLabels = MetricLabels.Default): OpenTelemetryMetrics[F] =
+  def addRequestsDuration(labels: MetricLabels = OTELMetricLabels.Default): OpenTelemetryMetrics[F] =
     copy(metrics = metrics :+ requestDuration(meter, labels))
 
   /** Registers a custom metric. */
@@ -50,7 +50,7 @@ object OpenTelemetryMetrics {
     * measured separately up to the point where the headers are determined, and then once again when the whole response body is complete.
     */
   def default[F[_]](otel: OpenTelemetry): OpenTelemetryMetrics[F] =
-    default(defaultMeter(otel), MetricLabels.Default)
+    default(defaultMeter(otel), OTELMetricLabels.Default)
 
   /** Registers default metrics (see other variants) using custom labels. */
   def default[F[_]](otel: OpenTelemetry, labels: MetricLabels): OpenTelemetryMetrics[F] = default(defaultMeter(otel), labels)
@@ -64,10 +64,10 @@ object OpenTelemetryMetrics {
     * Status is by default the status code class (1xx, 2xx, etc.), and phase can be either `headers` or `body` - request duration is
     * measured separately up to the point where the headers are determined, and then once again when the whole response body is complete.
     */
-  def default[F[_]](meter: Meter): OpenTelemetryMetrics[F] = default(meter, MetricLabels.Default)
+  def default[F[_]](meter: Meter): OpenTelemetryMetrics[F] = default(meter, OTELMetricLabels.Default)
 
   /** Registers default metrics (see other variants) using custom labels. */
-  def default[F[_]](meter: Meter, labels: MetricLabels = MetricLabels.Default): OpenTelemetryMetrics[F] =
+  def default[F[_]](meter: Meter, labels: MetricLabels = OTELMetricLabels.Default): OpenTelemetryMetrics[F] =
     OpenTelemetryMetrics(
       meter,
       List[Metric[F, _]](
@@ -87,21 +87,8 @@ object OpenTelemetryMetrics {
       onRequest = (req, counter, m) => {
         m.unit {
           EndpointMetric()
-            .onEndpointRequest { ep =>
-              m.eval {
-                val attrs = asOpenTelemetryAttributes(labels, ep, req)
-                println(s"[DEBUG] Incrementing active requests with attributes: $attrs")
-
-                counter.add(1, attrs)
-              }
-            }
-            .onResponseBody { (ep, _) =>
-              m.eval {
-                val attrs = asOpenTelemetryAttributes(labels, ep, req)
-                println(s"[DEBUG] Decrementing active requests with attributes: $attrs")
-                counter.add(-1, attrs)
-              }
-            }
+            .onEndpointRequest { ep => m.eval(counter.add(1, asOpenTelemetryAttributes(labels, ep, req))) }
+            .onResponseBody { (ep, _) => m.eval(counter.add(-1, asOpenTelemetryAttributes(labels, ep, req))) }
             .onException { (ep, _) => m.eval(counter.add(-1, asOpenTelemetryAttributes(labels, ep, req))) }
         }
       }
@@ -119,11 +106,9 @@ object OpenTelemetryMetrics {
           EndpointMetric()
             .onResponseBody { (ep, res) =>
               m.eval {
-                val otLabels: Attributes =
+                val otLabels =
                   merge(asOpenTelemetryAttributes(labels, ep, req), asOpenTelemetryAttributes(labels, Right(res), None))
 
-                println(s"[DEBUG] Incrementing total requests with labels: $otLabels")
-
                 counter.add(1, otLabels)
               }
             }
@@ -138,7 +123,6 @@ object OpenTelemetryMetrics {
       }
     )
 
-  
   def requestDuration[F[_]](meter: Meter, labels: MetricLabels): Metric[F, DoubleHistogram] =
     Metric[F, DoubleHistogram](
       meter
@@ -149,7 +133,7 @@ object OpenTelemetryMetrics {
       onRequest = (req, recorder, m) =>
         m.eval {
           val requestStart = Instant.now()
-          def duration = Duration.between(requestStart, Instant.now()).toMillis.toDouble / 1000.0
+          def duration = Duration.between(requestStart, Instant.now()).toMillis.toDouble
           EndpointMetric()
             .onResponseHeaders { (ep, res) =>
               m.eval {
diff --git a/metrics/opentelemetry-metrics/src/test/scala/sttp/tapir/server/metrics/opentelemetry/OpenTelemetryMetricsTest.scala b/metrics/opentelemetry-metrics/src/test/scala/sttp/tapir/server/metrics/opentelemetry/OpenTelemetryMetricsTest.scala
index 4581b09594..093cd8d85f 100644
--- a/metrics/opentelemetry-metrics/src/test/scala/sttp/tapir/server/metrics/opentelemetry/OpenTelemetryMetricsTest.scala
+++ b/metrics/opentelemetry-metrics/src/test/scala/sttp/tapir/server/metrics/opentelemetry/OpenTelemetryMetricsTest.scala
@@ -101,8 +101,8 @@ class OpenTelemetryMetricsTest extends AnyFlatSpec with Matchers {
               "GET",
               AttributeKey.stringKey("path"),
               "/person",
-    AttributeKey.longKey("http.response.status_code").asInstanceOf[AttributeKey[Long]], // Explicitly cast to Long
-              200L
+              AttributeKey.stringKey("http.response.status_code"),
+              "200"
             ) && dp.getValue == 2 =>
           true
         case dp
@@ -111,8 +111,8 @@ class OpenTelemetryMetricsTest extends AnyFlatSpec with Matchers {
               "GET",
               AttributeKey.stringKey("path"),
               "/person",
-    AttributeKey.longKey("http.response.status_code").asInstanceOf[AttributeKey[Long]], // Explicitly cast to Long
-              400L
+              AttributeKey.stringKey("http.response.status_code"),
+              "400"
             ) && dp.getValue == 2 =>
           true
         case _ => false
@@ -154,8 +154,10 @@ class OpenTelemetryMetricsTest extends AnyFlatSpec with Matchers {
         "GET",
         AttributeKey.stringKey("path"),
         "/person",
-    AttributeKey.longKey("http.response.status_code").asInstanceOf[AttributeKey[Long]], // Explicitly cast to Long
-        200L
+        AttributeKey.stringKey("http.response.status_code"),
+        "200",
+        AttributeKey.stringKey("phase"),
+        "body"
       )
     )
   }
@@ -209,8 +211,8 @@ class OpenTelemetryMetricsTest extends AnyFlatSpec with Matchers {
       "GET",
       AttributeKey.stringKey("path"),
       "/person",
-    AttributeKey.longKey("http.response.status_code").asInstanceOf[AttributeKey[Long]], // Explicitly cast to Long
-      500L
+      AttributeKey.stringKey("http.response.status_code"),
+      "500"
     )
     point.getValue shouldBe 1
   }
diff --git a/server/core/src/main/scala/sttp/tapir/server/metrics/Metric.scala b/server/core/src/main/scala/sttp/tapir/server/metrics/Metric.scala
index 8c90e9fb3b..05bb9762ed 100644
--- a/server/core/src/main/scala/sttp/tapir/server/metrics/Metric.scala
+++ b/server/core/src/main/scala/sttp/tapir/server/metrics/Metric.scala
@@ -64,3 +64,22 @@ object MetricLabels {
     )
   )
 }
+
+object OTELMetricLabels {
+
+  /** Labels request by path and http.request.method, response by http.response.status_code */
+  lazy val Default: MetricLabels = MetricLabels(
+    forRequest = List(
+      "http.request.method" -> { case (_, req) => req.method.method },
+      "path" -> { case (ep, _) => ep.showPathTemplate(showQueryParam = None) }
+    ),
+    forResponse = List(
+      "http.response.status_code" -> {
+        // OpenTelemetry-compliant
+        case Right(r) => r.code.code.toString
+        // Default to 500 for exceptions
+        case Left(_) => "500"
+      }
+    )
+  )
+}

From ce718700816742ff1b450d5e9c7c2ccffe0693b7 Mon Sep 17 00:00:00 2001
From: Vamshi Maskuri <117595548+varshith257@users.noreply.github.com>
Date: Sun, 3 Nov 2024 09:49:28 +0530
Subject: [PATCH 4/9] feat!: add review comments

---
 .../opentelemetry/OpenTelemetryMetrics.scala       | 14 +++++++-------
 .../scala/sttp/tapir/server/metrics/Metric.scala   | 14 ++++++++------
 2 files changed, 15 insertions(+), 13 deletions(-)

diff --git a/metrics/opentelemetry-metrics/src/main/scala/sttp/tapir/server/metrics/opentelemetry/OpenTelemetryMetrics.scala b/metrics/opentelemetry-metrics/src/main/scala/sttp/tapir/server/metrics/opentelemetry/OpenTelemetryMetrics.scala
index d52368fd2e..566944d308 100644
--- a/metrics/opentelemetry-metrics/src/main/scala/sttp/tapir/server/metrics/opentelemetry/OpenTelemetryMetrics.scala
+++ b/metrics/opentelemetry-metrics/src/main/scala/sttp/tapir/server/metrics/opentelemetry/OpenTelemetryMetrics.scala
@@ -7,7 +7,7 @@ import OpenTelemetryMetrics._
 import io.opentelemetry.api.OpenTelemetry
 import sttp.tapir.model.ServerRequest
 import sttp.tapir.server.interceptor.metrics.MetricsRequestInterceptor
-import sttp.tapir.server.metrics.{EndpointMetric, Metric, MetricLabels, OTELMetricLabels}
+import sttp.tapir.server.metrics.{EndpointMetric, Metric, MetricLabels}
 import sttp.tapir.server.model.ServerResponse
 
 import java.time.{Duration, Instant}
@@ -15,15 +15,15 @@ import java.time.{Duration, Instant}
 case class OpenTelemetryMetrics[F[_]](meter: Meter, metrics: List[Metric[F, _]]) {
 
   /** Registers a `request_active{path, method}` up-down-counter (assuming default labels). */
-  def addRequestsActive(labels: MetricLabels = OTELMetricLabels.Default): OpenTelemetryMetrics[F] =
+  def addRequestsActive(labels: MetricLabels = MetricLabels.OpenTelemetryAttributes): OpenTelemetryMetrics[F] =
     copy(metrics = metrics :+ requestActive(meter, labels))
 
   /** Registers a `request_total{path, method, status}` counter (assuming default labels). */
-  def addRequestsTotal(labels: MetricLabels = OTELMetricLabels.Default): OpenTelemetryMetrics[F] =
+  def addRequestsTotal(labels: MetricLabels = MetricLabels.OpenTelemetryAttributes): OpenTelemetryMetrics[F] =
     copy(metrics = metrics :+ requestTotal(meter, labels))
 
   /** Registers a `request_duration_seconds{path, method, status, phase}` histogram (assuming default labels). */
-  def addRequestsDuration(labels: MetricLabels = OTELMetricLabels.Default): OpenTelemetryMetrics[F] =
+  def addRequestsDuration(labels: MetricLabels = MetricLabels.OpenTelemetryAttributes): OpenTelemetryMetrics[F] =
     copy(metrics = metrics :+ requestDuration(meter, labels))
 
   /** Registers a custom metric. */
@@ -50,7 +50,7 @@ object OpenTelemetryMetrics {
     * measured separately up to the point where the headers are determined, and then once again when the whole response body is complete.
     */
   def default[F[_]](otel: OpenTelemetry): OpenTelemetryMetrics[F] =
-    default(defaultMeter(otel), OTELMetricLabels.Default)
+    default(defaultMeter(otel), MetricLabels.OpenTelemetryAttributes)
 
   /** Registers default metrics (see other variants) using custom labels. */
   def default[F[_]](otel: OpenTelemetry, labels: MetricLabels): OpenTelemetryMetrics[F] = default(defaultMeter(otel), labels)
@@ -64,10 +64,10 @@ object OpenTelemetryMetrics {
     * Status is by default the status code class (1xx, 2xx, etc.), and phase can be either `headers` or `body` - request duration is
     * measured separately up to the point where the headers are determined, and then once again when the whole response body is complete.
     */
-  def default[F[_]](meter: Meter): OpenTelemetryMetrics[F] = default(meter, OTELMetricLabels.Default)
+  def default[F[_]](meter: Meter): OpenTelemetryMetrics[F] = default(meter, MetricLabels.OpenTelemetryAttributes)
 
   /** Registers default metrics (see other variants) using custom labels. */
-  def default[F[_]](meter: Meter, labels: MetricLabels = OTELMetricLabels.Default): OpenTelemetryMetrics[F] =
+  def default[F[_]](meter: Meter, labels: MetricLabels = MetricLabels.OpenTelemetryAttributes): OpenTelemetryMetrics[F] =
     OpenTelemetryMetrics(
       meter,
       List[Metric[F, _]](
diff --git a/server/core/src/main/scala/sttp/tapir/server/metrics/Metric.scala b/server/core/src/main/scala/sttp/tapir/server/metrics/Metric.scala
index 05bb9762ed..5b3ba343d6 100644
--- a/server/core/src/main/scala/sttp/tapir/server/metrics/Metric.scala
+++ b/server/core/src/main/scala/sttp/tapir/server/metrics/Metric.scala
@@ -63,19 +63,21 @@ object MetricLabels {
       }
     )
   )
-}
-
-object OTELMetricLabels {
 
-  /** Labels request by path and http.request.method, response by http.response.status_code */
-  lazy val Default: MetricLabels = MetricLabels(
+  /** Default labels for OpenTelemetry-compliant metrics, as recommended here:
+    * https://opentelemetry.io/docs/specs/semconv/http/http-metrics/#http-server
+    *
+    *   - `http.request.method` - HTTP request method (e.g., GET, POST).
+    *   - `path` - The request path or route template.
+    *   - `http.response.status_code` - HTTP response status code (200, 404, etc.).
+    */
+  lazy val OpenTelemetryAttributes: MetricLabels = MetricLabels(
     forRequest = List(
       "http.request.method" -> { case (_, req) => req.method.method },
       "path" -> { case (ep, _) => ep.showPathTemplate(showQueryParam = None) }
     ),
     forResponse = List(
       "http.response.status_code" -> {
-        // OpenTelemetry-compliant
         case Right(r) => r.code.code.toString
         // Default to 500 for exceptions
         case Left(_) => "500"

From 1d8c612551863406cbed24e7db90ad52d5863e3a Mon Sep 17 00:00:00 2001
From: Vamshi Maskuri <117595548+varshith257@users.noreply.github.com>
Date: Fri, 8 Nov 2024 11:04:34 +0530
Subject: [PATCH 5/9] feat: add req additional attributes

---
 .../OpenTelemetryMetricsTest.scala            | 32 +++++++++++++++----
 .../sttp/tapir/server/metrics/Metric.scala    |  6 ++++
 2 files changed, 32 insertions(+), 6 deletions(-)

diff --git a/metrics/opentelemetry-metrics/src/test/scala/sttp/tapir/server/metrics/opentelemetry/OpenTelemetryMetricsTest.scala b/metrics/opentelemetry-metrics/src/test/scala/sttp/tapir/server/metrics/opentelemetry/OpenTelemetryMetricsTest.scala
index 093cd8d85f..1f0225c82a 100644
--- a/metrics/opentelemetry-metrics/src/test/scala/sttp/tapir/server/metrics/opentelemetry/OpenTelemetryMetricsTest.scala
+++ b/metrics/opentelemetry-metrics/src/test/scala/sttp/tapir/server/metrics/opentelemetry/OpenTelemetryMetricsTest.scala
@@ -55,7 +55,9 @@ class OpenTelemetryMetricsTest extends AnyFlatSpec with Matchers {
       AttributeKey.stringKey("http.request.method"),
       "GET",
       AttributeKey.stringKey("path"),
-      "/person"
+      "/person",
+      AttributeKey.stringKey("url.scheme"),
+      "http"
     )
     point.getValue shouldBe 1
 
@@ -65,7 +67,9 @@ class OpenTelemetryMetricsTest extends AnyFlatSpec with Matchers {
         AttributeKey.stringKey("http.request.method"),
         "GET",
         AttributeKey.stringKey("path"),
-        "/person"
+        "/person",
+        AttributeKey.stringKey("url.scheme"),
+        "http"
       )
       point.getValue shouldBe 0
     }
@@ -101,8 +105,12 @@ class OpenTelemetryMetricsTest extends AnyFlatSpec with Matchers {
               "GET",
               AttributeKey.stringKey("path"),
               "/person",
+              AttributeKey.stringKey("url.scheme"),
+              "http",
               AttributeKey.stringKey("http.response.status_code"),
-              "200"
+              "200",
+              AttributeKey.stringKey("error.type"),
+              ""
             ) && dp.getValue == 2 =>
           true
         case dp
@@ -111,8 +119,12 @@ class OpenTelemetryMetricsTest extends AnyFlatSpec with Matchers {
               "GET",
               AttributeKey.stringKey("path"),
               "/person",
+              AttributeKey.stringKey("url.scheme"),
+              "http",
               AttributeKey.stringKey("http.response.status_code"),
-              "400"
+              "400",
+              AttributeKey.stringKey("error.type"),
+              ""
             ) && dp.getValue == 2 =>
           true
         case _ => false
@@ -157,7 +169,11 @@ class OpenTelemetryMetricsTest extends AnyFlatSpec with Matchers {
         AttributeKey.stringKey("http.response.status_code"),
         "200",
         AttributeKey.stringKey("phase"),
-        "body"
+        "body",
+        AttributeKey.stringKey("url.scheme"),
+        "http",
+        AttributeKey.stringKey("error.type"),
+        ""
       )
     )
   }
@@ -211,8 +227,12 @@ class OpenTelemetryMetricsTest extends AnyFlatSpec with Matchers {
       "GET",
       AttributeKey.stringKey("path"),
       "/person",
+      AttributeKey.stringKey("url.scheme"),
+      "http",
       AttributeKey.stringKey("http.response.status_code"),
-      "500"
+      "500",
+      AttributeKey.stringKey("error.type"),
+      ""
     )
     point.getValue shouldBe 1
   }
diff --git a/server/core/src/main/scala/sttp/tapir/server/metrics/Metric.scala b/server/core/src/main/scala/sttp/tapir/server/metrics/Metric.scala
index 5b3ba343d6..c229f6bf24 100644
--- a/server/core/src/main/scala/sttp/tapir/server/metrics/Metric.scala
+++ b/server/core/src/main/scala/sttp/tapir/server/metrics/Metric.scala
@@ -74,6 +74,7 @@ object MetricLabels {
   lazy val OpenTelemetryAttributes: MetricLabels = MetricLabels(
     forRequest = List(
       "http.request.method" -> { case (_, req) => req.method.method },
+      "url.scheme" -> { case (_, req) => req.uri.scheme.getOrElse("unknown") },
       "path" -> { case (ep, _) => ep.showPathTemplate(showQueryParam = None) }
     ),
     forResponse = List(
@@ -81,6 +82,11 @@ object MetricLabels {
         case Right(r) => r.code.code.toString
         // Default to 500 for exceptions
         case Left(_) => "500"
+      },
+      "error.type" -> {
+        case Left(ex) => ex.getClass.getSimpleName
+        case Right(_) => ""
+
       }
     )
   )

From c8c19709641388eca40529785df9fc65f9373800 Mon Sep 17 00:00:00 2001
From: Vamshi Maskuri <117595548+varshith257@users.noreply.github.com>
Date: Fri, 8 Nov 2024 13:45:10 +0530
Subject: [PATCH 6/9] feat: move OTEL metrics related code to OTEL Module

---
 .../opentelemetry/OpenTelemetryMetrics.scala  | 39 ++++++++++++++++---
 1 file changed, 33 insertions(+), 6 deletions(-)

diff --git a/metrics/opentelemetry-metrics/src/main/scala/sttp/tapir/server/metrics/opentelemetry/OpenTelemetryMetrics.scala b/metrics/opentelemetry-metrics/src/main/scala/sttp/tapir/server/metrics/opentelemetry/OpenTelemetryMetrics.scala
index 566944d308..b46d6a421d 100644
--- a/metrics/opentelemetry-metrics/src/main/scala/sttp/tapir/server/metrics/opentelemetry/OpenTelemetryMetrics.scala
+++ b/metrics/opentelemetry-metrics/src/main/scala/sttp/tapir/server/metrics/opentelemetry/OpenTelemetryMetrics.scala
@@ -15,15 +15,15 @@ import java.time.{Duration, Instant}
 case class OpenTelemetryMetrics[F[_]](meter: Meter, metrics: List[Metric[F, _]]) {
 
   /** Registers a `request_active{path, method}` up-down-counter (assuming default labels). */
-  def addRequestsActive(labels: MetricLabels = MetricLabels.OpenTelemetryAttributes): OpenTelemetryMetrics[F] =
+  def addRequestsActive(labels: MetricLabels = OpenTelemetryAttributes): OpenTelemetryMetrics[F] =
     copy(metrics = metrics :+ requestActive(meter, labels))
 
   /** Registers a `request_total{path, method, status}` counter (assuming default labels). */
-  def addRequestsTotal(labels: MetricLabels = MetricLabels.OpenTelemetryAttributes): OpenTelemetryMetrics[F] =
+  def addRequestsTotal(labels: MetricLabels = OpenTelemetryAttributes): OpenTelemetryMetrics[F] =
     copy(metrics = metrics :+ requestTotal(meter, labels))
 
   /** Registers a `request_duration_seconds{path, method, status, phase}` histogram (assuming default labels). */
-  def addRequestsDuration(labels: MetricLabels = MetricLabels.OpenTelemetryAttributes): OpenTelemetryMetrics[F] =
+  def addRequestsDuration(labels: MetricLabels = OpenTelemetryAttributes): OpenTelemetryMetrics[F] =
     copy(metrics = metrics :+ requestDuration(meter, labels))
 
   /** Registers a custom metric. */
@@ -36,6 +36,33 @@ case class OpenTelemetryMetrics[F[_]](meter: Meter, metrics: List[Metric[F, _]])
 
 object OpenTelemetryMetrics {
 
+  /** Default labels for OpenTelemetry-compliant metrics, as recommended here:
+    * https://opentelemetry.io/docs/specs/semconv/http/http-metrics/#http-server
+    *
+    *   - `http.request.method` - HTTP request method (e.g., GET, POST).
+    *   - `path` - The request path or route template.
+    *   - `http.response.status_code` - HTTP response status code (200, 404, etc.).
+    */
+  lazy val OpenTelemetryAttributes: MetricLabels = MetricLabels(
+    forRequest = List(
+      "http.request.method" -> { case (_, req) => req.method.method },
+      "url.scheme" -> { case (_, req) => req.uri.scheme.getOrElse("unknown") },
+      "path" -> { case (ep, _) => ep.showPathTemplate(showQueryParam = None) }
+    ),
+    forResponse = List(
+      "http.response.status_code" -> {
+        case Right(r) => r.code.code.toString
+        // Default to 500 for exceptions
+        case Left(_) => "500"
+      },
+      "error.type" -> {
+        case Left(ex) => ex.getClass.getSimpleName
+        case Right(_) => ""
+
+      }
+    )
+  )
+
   def apply[F[_]](meter: Meter): OpenTelemetryMetrics[F] = apply(meter, Nil)
   def apply[F[_]](otel: OpenTelemetry): OpenTelemetryMetrics[F] = apply(defaultMeter(otel), Nil)
   def apply[F[_]](otel: OpenTelemetry, metrics: List[Metric[F, _]]): OpenTelemetryMetrics[F] = apply(defaultMeter(otel), metrics)
@@ -50,7 +77,7 @@ object OpenTelemetryMetrics {
     * measured separately up to the point where the headers are determined, and then once again when the whole response body is complete.
     */
   def default[F[_]](otel: OpenTelemetry): OpenTelemetryMetrics[F] =
-    default(defaultMeter(otel), MetricLabels.OpenTelemetryAttributes)
+    default(defaultMeter(otel), OpenTelemetryAttributes)
 
   /** Registers default metrics (see other variants) using custom labels. */
   def default[F[_]](otel: OpenTelemetry, labels: MetricLabels): OpenTelemetryMetrics[F] = default(defaultMeter(otel), labels)
@@ -64,10 +91,10 @@ object OpenTelemetryMetrics {
     * Status is by default the status code class (1xx, 2xx, etc.), and phase can be either `headers` or `body` - request duration is
     * measured separately up to the point where the headers are determined, and then once again when the whole response body is complete.
     */
-  def default[F[_]](meter: Meter): OpenTelemetryMetrics[F] = default(meter, MetricLabels.OpenTelemetryAttributes)
+  def default[F[_]](meter: Meter): OpenTelemetryMetrics[F] = default(meter, OpenTelemetryAttributes)
 
   /** Registers default metrics (see other variants) using custom labels. */
-  def default[F[_]](meter: Meter, labels: MetricLabels = MetricLabels.OpenTelemetryAttributes): OpenTelemetryMetrics[F] =
+  def default[F[_]](meter: Meter, labels: MetricLabels = OpenTelemetryAttributes): OpenTelemetryMetrics[F] =
     OpenTelemetryMetrics(
       meter,
       List[Metric[F, _]](

From ba7b18fa02f7807e6c4fa294961b3975463a3198 Mon Sep 17 00:00:00 2001
From: Vamshi Maskuri <117595548+varshith257@users.noreply.github.com>
Date: Fri, 8 Nov 2024 13:48:08 +0530
Subject: [PATCH 7/9] cleanup

---
 .../sttp/tapir/server/metrics/Metric.scala    | 27 -------------------
 1 file changed, 27 deletions(-)

diff --git a/server/core/src/main/scala/sttp/tapir/server/metrics/Metric.scala b/server/core/src/main/scala/sttp/tapir/server/metrics/Metric.scala
index c229f6bf24..8c90e9fb3b 100644
--- a/server/core/src/main/scala/sttp/tapir/server/metrics/Metric.scala
+++ b/server/core/src/main/scala/sttp/tapir/server/metrics/Metric.scala
@@ -63,31 +63,4 @@ object MetricLabels {
       }
     )
   )
-
-  /** Default labels for OpenTelemetry-compliant metrics, as recommended here:
-    * https://opentelemetry.io/docs/specs/semconv/http/http-metrics/#http-server
-    *
-    *   - `http.request.method` - HTTP request method (e.g., GET, POST).
-    *   - `path` - The request path or route template.
-    *   - `http.response.status_code` - HTTP response status code (200, 404, etc.).
-    */
-  lazy val OpenTelemetryAttributes: MetricLabels = MetricLabels(
-    forRequest = List(
-      "http.request.method" -> { case (_, req) => req.method.method },
-      "url.scheme" -> { case (_, req) => req.uri.scheme.getOrElse("unknown") },
-      "path" -> { case (ep, _) => ep.showPathTemplate(showQueryParam = None) }
-    ),
-    forResponse = List(
-      "http.response.status_code" -> {
-        case Right(r) => r.code.code.toString
-        // Default to 500 for exceptions
-        case Left(_) => "500"
-      },
-      "error.type" -> {
-        case Left(ex) => ex.getClass.getSimpleName
-        case Right(_) => ""
-
-      }
-    )
-  )
 }

From 673396085dbf7ce2c40050359eb81df5c123dcd7 Mon Sep 17 00:00:00 2001
From: Vamshi Maskuri <117595548+varshith257@users.noreply.github.com>
Date: Sat, 16 Nov 2024 20:55:15 +0530
Subject: [PATCH 8/9] Try to return an Option[String] with review suggestions

---
 .../opentelemetry/OpenTelemetryMetrics.scala  | 19 ++++++++++---------
 1 file changed, 10 insertions(+), 9 deletions(-)

diff --git a/metrics/opentelemetry-metrics/src/main/scala/sttp/tapir/server/metrics/opentelemetry/OpenTelemetryMetrics.scala b/metrics/opentelemetry-metrics/src/main/scala/sttp/tapir/server/metrics/opentelemetry/OpenTelemetryMetrics.scala
index b46d6a421d..eaf159c161 100644
--- a/metrics/opentelemetry-metrics/src/main/scala/sttp/tapir/server/metrics/opentelemetry/OpenTelemetryMetrics.scala
+++ b/metrics/opentelemetry-metrics/src/main/scala/sttp/tapir/server/metrics/opentelemetry/OpenTelemetryMetrics.scala
@@ -49,15 +49,16 @@ object OpenTelemetryMetrics {
       "url.scheme" -> { case (_, req) => req.uri.scheme.getOrElse("unknown") },
       "path" -> { case (ep, _) => ep.showPathTemplate(showQueryParam = None) }
     ),
-    forResponse = List(
-      "http.response.status_code" -> {
-        case Right(r) => r.code.code.toString
-        // Default to 500 for exceptions
-        case Left(_) => "500"
-      },
-      "error.type" -> {
-        case Left(ex) => ex.getClass.getSimpleName
-        case Right(_) => ""
+  forResponse = List(
+    "http.response.status_code" -> {
+      case Right(r) => Some(r.code.code.toString) 
+      case Left(_) => Some("500") 
+    },
+    "error.type" -> {
+      case Left(ex) => Some(ex.getClass.getName) 
+      case Right(_) => None 
+    }
+  ).collect { case (k, Some(v)) => k -> v }
 
       }
     )

From c654d5a1a2f6d42ec677a03eb637146767a00773 Mon Sep 17 00:00:00 2001
From: Vamshi Maskuri <117595548+varshith257@users.noreply.github.com>
Date: Sat, 16 Nov 2024 21:08:01 +0530
Subject: [PATCH 9/9] Fix compilation error

---
 .../server/metrics/opentelemetry/OpenTelemetryMetrics.scala     | 2 --
 1 file changed, 2 deletions(-)

diff --git a/metrics/opentelemetry-metrics/src/main/scala/sttp/tapir/server/metrics/opentelemetry/OpenTelemetryMetrics.scala b/metrics/opentelemetry-metrics/src/main/scala/sttp/tapir/server/metrics/opentelemetry/OpenTelemetryMetrics.scala
index eaf159c161..4f1d497e9e 100644
--- a/metrics/opentelemetry-metrics/src/main/scala/sttp/tapir/server/metrics/opentelemetry/OpenTelemetryMetrics.scala
+++ b/metrics/opentelemetry-metrics/src/main/scala/sttp/tapir/server/metrics/opentelemetry/OpenTelemetryMetrics.scala
@@ -60,8 +60,6 @@ object OpenTelemetryMetrics {
     }
   ).collect { case (k, Some(v)) => k -> v }
 
-      }
-    )
   )
 
   def apply[F[_]](meter: Meter): OpenTelemetryMetrics[F] = apply(meter, Nil)