fix(prometheus): Remove explicit timestamps from metric points

Author: carlosroman

CHANGELOG.md

@@ -15,6 +15,9 @@ Increment the:
 
 ## [Unreleased]
 
+* [EXPORTER] Remove explicit timestamps from metric points exported by Prometheus
+  [#3895](https://github.com/open-telemetry/opentelemetry-cpp/pull/3895)
+
 * [TEST] Add multi-threaded metrics benchmarks for shared vs per-thread counter
   [#3865](https://github.com/open-telemetry/opentelemetry-cpp/pull/3865)
 

exporters/prometheus/include/opentelemetry/exporters/prometheus/exporter_utils.h

@@ -153,7 +153,6 @@ class PrometheusExporterUtils
    * Add a target_info metric to collect resource attributes
    */
   static void SetTarget(const sdk::metrics::ResourceMetrics &data,
-                        std::chrono::nanoseconds time,
                         const opentelemetry::sdk::instrumentationscope::InstrumentationScope *scope,
                         std::vector<::prometheus::MetricFamily> *output);
 
@@ -166,7 +165,6 @@ class PrometheusExporterUtils
                       const opentelemetry::sdk::metrics::PointAttributes &labels,
                       const opentelemetry::sdk::instrumentationscope::InstrumentationScope *scope,
                       ::prometheus::MetricType type,
-                      std::chrono::nanoseconds time,
                       ::prometheus::MetricFamily *metric_family,
                       const opentelemetry::sdk::resource::Resource *resource);
 
@@ -180,7 +178,6 @@ class PrometheusExporterUtils
                       const std::vector<uint64_t> &counts,
                       const opentelemetry::sdk::metrics::PointAttributes &labels,
                       const opentelemetry::sdk::instrumentationscope::InstrumentationScope *scope,
-                      std::chrono::nanoseconds time,
                       ::prometheus::MetricFamily *metric_family,
                       const opentelemetry::sdk::resource::Resource *resource);
 
@@ -190,7 +187,6 @@ class PrometheusExporterUtils
   static void SetMetricBasic(
       ::prometheus::ClientMetric &metric,
       const opentelemetry::sdk::metrics::PointAttributes &labels,
-      std::chrono::nanoseconds time,
       const opentelemetry::sdk::instrumentationscope::InstrumentationScope *scope,
       const opentelemetry::sdk::resource::Resource *resource);
 

exporters/prometheus/src/exporter_utils.cc

@@ -139,7 +139,6 @@ std::vector<prometheus_client::MetricFamily> PrometheusExporterUtils::TranslateT
   if (populate_target_info && !data.scope_metric_data_.empty())
   {
     SetTarget(data,
-              data.scope_metric_data_.begin()->metric_data_.begin()->end_ts.time_since_epoch(),
               without_otel_scope ? nullptr : (*data.scope_metric_data_.begin()).scope_, &output);
   }
 
@@ -151,7 +150,6 @@ std::vector<prometheus_client::MetricFamily> PrometheusExporterUtils::TranslateT
       auto unit        = metric_data.instrument_descriptor.unit_;
       prometheus_client::MetricFamily metric_family;
       metric_family.help = metric_data.instrument_descriptor.description_;
-      auto time          = metric_data.end_ts.time_since_epoch();
       auto front         = metric_data.point_data_attr_.front();
       auto kind          = getAggregationType(front.point_data);
       bool is_monotonic  = true;
@@ -185,7 +183,7 @@ std::vector<prometheus_client::MetricFamily> PrometheusExporterUtils::TranslateT
             sum = static_cast<double>(nostd::get<int64_t>(histogram_point_data.sum_));
           }
           SetData(std::vector<double>{sum, static_cast<double>(histogram_point_data.count_)},
-                  boundaries, counts, point_data_attr.attributes, scope, time, &metric_family,
+                  boundaries, counts, point_data_attr.attributes, scope, &metric_family,
                   data.resource_);
         }
         else if (type == prometheus_client::MetricType::Gauge)
@@ -196,15 +194,15 @@ std::vector<prometheus_client::MetricFamily> PrometheusExporterUtils::TranslateT
             auto last_value_point_data =
                 nostd::get<sdk::metrics::LastValuePointData>(point_data_attr.point_data);
             std::vector<metric_sdk::ValueType> values{last_value_point_data.value_};
-            SetData(values, point_data_attr.attributes, scope, type, time, &metric_family,
+            SetData(values, point_data_attr.attributes, scope, type, &metric_family,
                     data.resource_);
           }
           else if (nostd::holds_alternative<sdk::metrics::SumPointData>(point_data_attr.point_data))
           {
             auto sum_point_data =
                 nostd::get<sdk::metrics::SumPointData>(point_data_attr.point_data);
             std::vector<metric_sdk::ValueType> values{sum_point_data.value_};
-            SetData(values, point_data_attr.attributes, scope, type, time, &metric_family,
+            SetData(values, point_data_attr.attributes, scope, type, &metric_family,
                     data.resource_);
           }
           else
@@ -221,7 +219,7 @@ std::vector<prometheus_client::MetricFamily> PrometheusExporterUtils::TranslateT
             auto sum_point_data =
                 nostd::get<sdk::metrics::SumPointData>(point_data_attr.point_data);
             std::vector<metric_sdk::ValueType> values{sum_point_data.value_};
-            SetData(values, point_data_attr.attributes, scope, type, time, &metric_family,
+            SetData(values, point_data_attr.attributes, scope, type, &metric_family,
                     data.resource_);
           }
           else
@@ -605,7 +603,6 @@ prometheus_client::MetricType PrometheusExporterUtils::TranslateType(
 
 void PrometheusExporterUtils::SetTarget(
     const sdk::metrics::ResourceMetrics &data,
-    std::chrono::nanoseconds time,
     const opentelemetry::sdk::instrumentationscope::InstrumentationScope *scope,
     std::vector<::prometheus::MetricFamily> *output)
 {
@@ -624,7 +621,7 @@ void PrometheusExporterUtils::SetTarget(
   metric.info.value                       = 1.0;
 
   metric_sdk::PointAttributes empty_attributes;
-  SetMetricBasic(metric, empty_attributes, time, scope, data.resource_);
+  SetMetricBasic(metric, empty_attributes, scope, data.resource_);
 
   for (auto &label : data.resource_->GetAttributes())
   {
@@ -645,13 +642,12 @@ void PrometheusExporterUtils::SetData(
     const metric_sdk::PointAttributes &labels,
     const opentelemetry::sdk::instrumentationscope::InstrumentationScope *scope,
     prometheus_client::MetricType type,
-    std::chrono::nanoseconds time,
     prometheus_client::MetricFamily *metric_family,
     const opentelemetry::sdk::resource::Resource *resource)
 {
   metric_family->metric.emplace_back();
   prometheus_client::ClientMetric &metric = metric_family->metric.back();
-  SetMetricBasic(metric, labels, time, scope, resource);
+  SetMetricBasic(metric, labels, scope, resource);
   SetValue(values, type, &metric);
 }
 
@@ -666,13 +662,12 @@ void PrometheusExporterUtils::SetData(
     const std::vector<uint64_t> &counts,
     const metric_sdk::PointAttributes &labels,
     const opentelemetry::sdk::instrumentationscope::InstrumentationScope *scope,
-    std::chrono::nanoseconds time,
     prometheus_client::MetricFamily *metric_family,
     const opentelemetry::sdk::resource::Resource *resource)
 {
   metric_family->metric.emplace_back();
   prometheus_client::ClientMetric &metric = metric_family->metric.back();
-  SetMetricBasic(metric, labels, time, scope, resource);
+  SetMetricBasic(metric, labels, scope, resource);
   SetValue(values, boundaries, counts, &metric);
 }
 
@@ -682,11 +677,9 @@ void PrometheusExporterUtils::SetData(
 void PrometheusExporterUtils::SetMetricBasic(
     prometheus_client::ClientMetric &metric,
     const metric_sdk::PointAttributes &labels,
-    std::chrono::nanoseconds time,
     const opentelemetry::sdk::instrumentationscope::InstrumentationScope *scope,
     const opentelemetry::sdk::resource::Resource *resource)
 {
-  metric.timestamp_ms = time.count() / 1000000;
   if (labels.empty() && nullptr == resource)
   {
     return;

exporters/prometheus/test/exporter_utils_test.cc

@@ -90,10 +90,10 @@ static void assert_basic(prometheus_client::MetricFamily &metric,
   ASSERT_EQ(metric.help, description);    // description not changed
   ASSERT_EQ(metric.type, type);           // type translated
 
+  // Prometheus metric data points should not have explicit timestamps
   for (const prometheus::ClientMetric &cm : metric.metric)
   {
-    // end_ts is set as 1766662560000
-    ASSERT_EQ(cm.timestamp_ms, 1766662560);
+    ASSERT_EQ(cm.timestamp_ms, 0);
   }
 
   auto metric_data = metric.metric[0];