prometheus example

examples/prometheus/BUILD

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+cc_binary(
+    name = "prometheus_example",
+    srcs = [
+        "main.cc",
+    ],
+    linkopts = ["-pthread"],
+    tags = ["ostream"],
+    deps = [
+        "//api",
+        "//examples/common/metrics_foo_library:common_metrics_foo_library",
+        "//exporters/prometheus:prometheus_exporter",
+        "//sdk/src/metrics",
+    ],
+)

examples/prometheus/main.cc

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+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+#ifndef ENABLE_METRICS_PREVIEW
+#  include <memory>
+#  include <thread>
+#  include "opentelemetry/exporters/prometheus/exporter.h"
+#  include "opentelemetry/metrics/provider.h"
+#  include "opentelemetry/sdk/metrics/aggregation/default_aggregation.h"
+#  include "opentelemetry/sdk/metrics/aggregation/histogram_aggregation.h"
+#  include "opentelemetry/sdk/metrics/export/periodic_exporting_metric_reader.h"
+#  include "opentelemetry/sdk/metrics/meter.h"
+#  include "opentelemetry/sdk/metrics/meter_provider.h"
+
+#  ifdef BAZEL_BUILD
+#    include "examples/common/metrics_foo_library/foo_library.h"
+#  else
+#    include "metrics_foo_library/foo_library.h"
+#  endif
+
+namespace metric_sdk      = opentelemetry::sdk::metrics;
+namespace nostd           = opentelemetry::nostd;
+namespace common          = opentelemetry::common;
+namespace exportermetrics = opentelemetry::exporter::metrics;
+namespace metrics_api     = opentelemetry::metrics;
+
+namespace
+{
+
+void initMetrics(const std::string &name)
+{
+  std::string addr{"localhost:8080"};
+  std::puts("PrometheusExporter example program running ...");
+
+  std::unique_ptr<metric_sdk::MetricExporter> exporter{
+      new exportermetrics::PrometheusExporter(addr)};
+  std::vector<std::unique_ptr<metric_sdk::MetricExporter>> exporters;
+
+  std::string version{"1.2.0"};
+  std::string schema{"https://opentelemetry.io/schemas/1.2.0"};
+
+  // Initialize and set the global MeterProvider
+  metric_sdk::PeriodicExportingMetricReaderOptions options;
+  options.export_interval_millis = std::chrono::milliseconds(1000);
+  options.export_timeout_millis  = std::chrono::milliseconds(500);
+  std::unique_ptr<metric_sdk::MetricReader> reader{
+      new metric_sdk::PeriodicExportingMetricReader(std::move(exporter), options)};
+  auto provider = std::shared_ptr<metrics_api::MeterProvider>(
+      new metric_sdk::MeterProvider(std::move(exporters)));
+  auto p = std::static_pointer_cast<metric_sdk::MeterProvider>(provider);
+  p->AddMetricReader(std::move(reader));
+
+  // counter view
+  std::unique_ptr<metric_sdk::InstrumentSelector> instrument_selector{
+      new metric_sdk::InstrumentSelector(metric_sdk::InstrumentType::kCounter, name)};
+  std::unique_ptr<metric_sdk::MeterSelector> meter_selector{
+      new metric_sdk::MeterSelector(name, version, schema)};
+  std::unique_ptr<metric_sdk::View> sum_view{
+      new metric_sdk::View{name, "description", metric_sdk::AggregationType::kSum}};
+  p->AddView(std::move(instrument_selector), std::move(meter_selector), std::move(sum_view));
+
+  // histogram view
+  std::unique_ptr<metric_sdk::InstrumentSelector> histogram_instrument_selector{
+      new metric_sdk::InstrumentSelector(metric_sdk::InstrumentType::kHistogram, name)};
+  std::unique_ptr<metric_sdk::MeterSelector> histogram_meter_selector{
+      new metric_sdk::MeterSelector(name, version, schema)};
+  std::unique_ptr<metric_sdk::View> histogram_view{
+      new metric_sdk::View{name, "description", metric_sdk::AggregationType::kHistogram}};
+  p->AddView(std::move(histogram_instrument_selector), std::move(histogram_meter_selector),
+             std::move(histogram_view));
+  metrics_api::Provider::SetMeterProvider(provider);
+}
+}  // namespace
+int main(int argc, char **argv)
+{
+  if (argc != 2)
+  {
+    std::puts("invalid number of command line arguments");
+    return 0;
+  }
+
+  std::string example_type(argv[1]);
+  std::string name{"prometheus_example"};
+  initMetrics(name);
+
+  if (example_type == "counter")
+  {
+    foo_library::counter_example(name);
+  }
+  else
+  {
+    foo_library::histogram_example(name);
+  }
+}
+#else
+int main() {}
+#endif

examples/prometheus/prometheus.yml

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+global:
+  scrape_interval: 5s
+  scrape_timeout: 2s
+  evaluation_interval: 5s
+alerting:
+  alertmanagers:
+  - follow_redirects: true
+    scheme: http
+    timeout: 5s
+    api_version: v2
+    static_configs:
+    - targets: [localhost:8080]
+scrape_configs:
+  - job_name: otel
+    static_configs:
+      - targets: ['localhost:8080']

examples/prometheus/run.sh

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+docker run -p 9090:9090 -v $(pwd):/etc/prometheus --network="host" prom/prometheus