[SDK] Implement env var configuration for PeriodicExportingMetricReader (open-telemetry#3549)

Author: mathieurobin1

CHANGELOG.md

@@ -18,6 +18,9 @@ Increment the:
 * [TEST] Shared otel-cpp libs linked to latest static protobuf and grpc
   [#3544](https://github.com/open-telemetry/opentelemetry-cpp/pull/3544)
 
+* [SDK] Implement env var configuration for PeriodicExportingMetricReader
+  [#3549](https://github.com/open-telemetry/opentelemetry-cpp/pull/3549)
+
 ## [1.22 2025-07-11]
 
 * [DOC] Udpate link to membership document
@@ -1407,7 +1410,7 @@ Important changes:
 * [ETW EXPORTER] Remove namespace using in ETW exporter which affects global
   namespace
   [#2531](https://github.com/open-telemetry/opentelemetry-cpp/pull/2531)
-* [BUILD] Don't invoke vcpkg from this repo with CMAKE_TOOLCHAIN_FILE set
+* [BUILD] Don't invoke vcpkg from this repo with CMAKE_TOOLCHAIN_FILE set
   [#2527](https://github.com/open-telemetry/opentelemetry-cpp/pull/2527)
 * [EXPORTER] Async exporting for otlp grpc
   [#2407](https://github.com/open-telemetry/opentelemetry-cpp/pull/2407)

ext/src/dll/input.src

@@ -16,6 +16,7 @@ ForceFlush@LoggerProvider@logs@sdk@v1@opentelemetry
 OStreamLogRecordExporter@logs@exporter@v1@opentelemetry
 Create@OStreamMetricExporterFactory@metrics@exporter@v1@opentelemetry
 Create@PeriodicExportingMetricReaderFactory@metrics@sdk@v1@opentelemetry
+PeriodicExportingMetricReaderOptions@metrics@sdk@v1@opentelemetry
 Create@MeterProviderFactory@metrics@sdk@v1@opentelemetry
 Create@MeterContextFactory@metrics@sdk@v1@opentelemetry
 Create@ViewFactory@metrics@sdk@v1@opentelemetry

sdk/include/opentelemetry/sdk/metrics/export/periodic_exporting_metric_reader_options.h

@@ -3,10 +3,10 @@
 
 #pragma once
 
-#include "opentelemetry/version.h"
-
 #include <chrono>
 
+#include "opentelemetry/version.h"
+
 OPENTELEMETRY_BEGIN_NAMESPACE
 namespace sdk
 {
@@ -20,14 +20,15 @@ constexpr std::chrono::milliseconds kExportTimeOutMillis  = std::chrono::millise
  * Struct to hold PeriodicExortingMetricReader options.
  */
 
-struct PeriodicExportingMetricReaderOptions
+struct OPENTELEMETRY_EXPORT PeriodicExportingMetricReaderOptions
 {
   /* The time interval between two consecutive exports. */
-  std::chrono::milliseconds export_interval_millis =
-      std::chrono::milliseconds(kExportIntervalMillis);
+  std::chrono::milliseconds export_interval_millis;
 
   /*  how long the export can run before it is cancelled. */
-  std::chrono::milliseconds export_timeout_millis = std::chrono::milliseconds(kExportTimeOutMillis);
+  std::chrono::milliseconds export_timeout_millis;
+
+  PeriodicExportingMetricReaderOptions();
 };
 
 }  // namespace metrics

sdk/src/metrics/CMakeLists.txt

@@ -15,6 +15,7 @@ add_library(
   instrument_metadata_validator.cc
   export/periodic_exporting_metric_reader.cc
   export/periodic_exporting_metric_reader_factory.cc
+  export/periodic_exporting_metric_reader_options.cc
   state/filtered_ordered_attribute_map.cc
   state/metric_collector.cc
   state/observable_registry.cc

sdk/src/metrics/export/periodic_exporting_metric_reader_options.cc

@@ -0,0 +1,35 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+#include <chrono>
+
+#include "opentelemetry/nostd/string_view.h"
+#include "opentelemetry/sdk/common/env_variables.h"
+#include "opentelemetry/sdk/metrics/export/periodic_exporting_metric_reader_options.h"
+#include "opentelemetry/version.h"
+
+OPENTELEMETRY_BEGIN_NAMESPACE
+namespace sdk
+{
+namespace metrics
+{
+
+std::chrono::milliseconds GetEnvDuration(nostd::string_view env_var_name,
+                                         std::chrono::milliseconds default_value)
+{
+  std::chrono::system_clock::duration duration;
+  if (common::GetDurationEnvironmentVariable(env_var_name.data(), duration))
+  {
+    return std::chrono::duration_cast<std::chrono::milliseconds>(duration);
+  }
+  return default_value;
+}
+
+PeriodicExportingMetricReaderOptions::PeriodicExportingMetricReaderOptions()
+    : export_interval_millis(GetEnvDuration("OTEL_METRIC_EXPORT_INTERVAL", kExportIntervalMillis)),
+      export_timeout_millis(GetEnvDuration("OTEL_METRIC_EXPORT_TIMEOUT", kExportTimeOutMillis))
+{}
+
+}  // namespace metrics
+}  // namespace sdk
+OPENTELEMETRY_END_NAMESPACE

sdk/test/metrics/periodic_exporting_metric_reader_test.cc

@@ -4,6 +4,7 @@
 #include <gtest/gtest.h>
 #include <stddef.h>
 #include <chrono>
+#include <cstdlib>
 #include <memory>
 #include <ratio>
 #include <thread>
@@ -18,6 +19,12 @@
 #include "opentelemetry/sdk/metrics/instruments.h"
 #include "opentelemetry/sdk/metrics/push_metric_exporter.h"
 
+#if defined(_MSC_VER)
+#  include "opentelemetry/sdk/common/env_variables.h"
+using opentelemetry::sdk::common::setenv;
+using opentelemetry::sdk::common::unsetenv;
+#endif
+
 using namespace opentelemetry;
 using namespace opentelemetry::sdk::instrumentationscope;
 using namespace opentelemetry::sdk::metrics;
@@ -76,7 +83,7 @@ class MockMetricProducer : public MetricProducer
   size_t data_sent_size_{0};
 };
 
-TEST(PeriodicExporingMetricReader, BasicTests)
+TEST(PeriodicExportingMetricReader, BasicTests)
 {
   std::unique_ptr<PushMetricExporter> exporter(
       new MockPushMetricExporter(std::chrono::milliseconds{0}));
@@ -95,7 +102,7 @@ TEST(PeriodicExporingMetricReader, BasicTests)
             static_cast<MockMetricProducer *>(&producer)->GetDataCount());
 }
 
-TEST(PeriodicExporingMetricReader, Timeout)
+TEST(PeriodicExportingMetricReader, Timeout)
 {
   std::unique_ptr<PushMetricExporter> exporter(
       new MockPushMetricExporter(std::chrono::milliseconds{2000}));
@@ -109,3 +116,32 @@ TEST(PeriodicExporingMetricReader, Timeout)
   std::this_thread::sleep_for(std::chrono::milliseconds(1000));
   reader->Shutdown();
 }
+
+TEST(PeriodicExportingMetricReaderOptions, UsesEnvVars)
+{
+  const char *env_interval = "OTEL_METRIC_EXPORT_INTERVAL";
+  const char *env_timeout  = "OTEL_METRIC_EXPORT_TIMEOUT";
+
+  setenv(env_interval, "1500ms", 1);
+  setenv(env_timeout, "1000ms", 1);
+
+  PeriodicExportingMetricReaderOptions options;
+  EXPECT_EQ(options.export_interval_millis, std::chrono::milliseconds(1500));
+  EXPECT_EQ(options.export_timeout_millis, std::chrono::milliseconds(1000));
+
+  unsetenv(env_interval);
+  unsetenv(env_timeout);
+}
+
+TEST(PeriodicExportingMetricReaderOptions, UsesDefault)
+{
+  const char *env_interval = "OTEL_METRIC_EXPORT_INTERVAL";
+  const char *env_timeout  = "OTEL_METRIC_EXPORT_TIMEOUT";
+
+  unsetenv(env_interval);
+  unsetenv(env_timeout);
+
+  PeriodicExportingMetricReaderOptions options;
+  EXPECT_EQ(options.export_interval_millis, std::chrono::milliseconds(60000));
+  EXPECT_EQ(options.export_timeout_millis, std::chrono::milliseconds(30000));
+}