OTel Cpp Metrics with OTLP gRPC Exporter

[julianocosta89]

request for assistance
I'm trying to add metrics to the OTel demo, but I'm struggling for some time.
Would someone be able to shed some light in my path?

I have everything that I've added in a branch: https://github.com/julianocosta89/opentelemetry-demo/tree/cpp-metrics/src/currencyservice

And the detailed changes below:

I'm using OTel version 1.8.2
I've added to the target_link_libraries the following:

opentelemetry_metrics opentelemetry_exporter_otlp_grpc_metrics

And at the moment I have everything in a single header file, just to test it out:

#include "opentelemetry/exporters/otlp/otlp_grpc_metric_exporter_factory.h"
#include "opentelemetry/metrics/provider.h"
#include "opentelemetry/sdk/metrics/aggregation/default_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"

namespace metric_sdk    = opentelemetry::sdk::metrics;
namespace common        = opentelemetry::common;
namespace metrics_api   = opentelemetry::metrics;
namespace otlp_exporter = opentelemetry::exporter::otlp;

namespace
{

	void initMeter() {
		std::string version{"0.1.0"};
		std::string name{"otel"};
		std::string schema{"https://opentelemetry.io/schemas/1.2.0"};

		//Build MetricExporter
		otlp_exporter::OtlpGrpcMetricExporterOptions otlpOptions;
		otlpOptions.endpoint = "otelcol:4317";
		otlpOptions.aggregation_temporality = metric_sdk::AggregationTemporality::kDelta;
		auto exporter = otlp_exporter::OtlpGrpcMetricExporterFactory::Create(otlpOptions);

		//Build MeterProvider and Reader
		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());
		auto p = std::static_pointer_cast<metric_sdk::MeterProvider>(provider);
		p->AddMetricReader(std::move(reader));
		metrics_api::Provider::SetMeterProvider(provider);

		//Build Meter for Counter
		std::string counter_name = name + "_counter";
		std::unique_ptr<metric_sdk::InstrumentSelector> instrument_selector{
			new metric_sdk::InstrumentSelector(metric_sdk::InstrumentType::kCounter, counter_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));

		//Build instrument
		auto meter = provider->GetMeter(name, "0.0.0");
		auto double_counter = meter->CreateDoubleCounter(counter_name);
		// Create a label set which annotates metric values
		std::map<std::string, std::string> labels = { {"key", "value"} };
		auto labelkv = common::KeyValueIterableView<decltype(labels)>{ labels };
		double_counter->Add(1.0, labelkv);

	}
}

Whenever I try to build the sample, I'm getting:

#0 11.86 /usr/lib/gcc/x86_64-alpine-linux-musl/12.2.1/../../../../x86_64-alpine-linux-musl/bin/ld: /usr/local/lib/libopentelemetry_exporter_otlp_grpc_metrics.a(otlp_grpc_metric_exporter.cc.o): in function `opentelemetry::v1::exporter::otlp::OtlpGrpcMetricExporter::OtlpGrpcMetricExporter(opentelemetry::v1::exporter::otlp::OtlpGrpcMetricExporterOptions const&)':
#0 11.86 otlp_grpc_metric_exporter.cc:(.text+0xb64): undefined reference to `opentelemetry::v1::exporter::otlp::OtlpMetricUtils::ChooseTemporalitySelector(opentelemetry::v1::sdk::metrics::AggregationTemporality)'
#0 11.86 /usr/lib/gcc/x86_64-alpine-linux-musl/12.2.1/../../../../x86_64-alpine-linux-musl/bin/ld: otlp_grpc_metric_exporter.cc:(.text+0xba2): undefined reference to `opentelemetry::proto::collector::metrics::v1::MetricsService::NewStub(std::shared_ptr<grpc::ChannelInterface> const&, grpc::StubOptions const&)'
#0 11.86 /usr/lib/gcc/x86_64-alpine-linux-musl/12.2.1/../../../../x86_64-alpine-linux-musl/bin/ld: /usr/local/lib/libopentelemetry_exporter_otlp_grpc_metrics.a(otlp_grpc_metric_exporter.cc.o): in function `opentelemetry::v1::exporter::otlp::OtlpGrpcMetricExporter::OtlpGrpcMetricExporter(std::unique_ptr<opentelemetry::proto::collector::metrics::v1::MetricsService::StubInterface, std::default_delete<opentelemetry::proto::collector::metrics::v1::MetricsService::StubInterface> >)':
#0 11.86 otlp_grpc_metric_exporter.cc:(.text+0xec7): undefined reference to `opentelemetry::v1::exporter::otlp::OtlpMetricUtils::ChooseTemporalitySelector(opentelemetry::v1::sdk::metrics::AggregationTemporality)'
#0 11.86 /usr/lib/gcc/x86_64-alpine-linux-musl/12.2.1/../../../../x86_64-alpine-linux-musl/bin/ld: /usr/local/lib/libopentelemetry_exporter_otlp_grpc_metrics.a(otlp_grpc_metric_exporter.cc.o): in function `opentelemetry::v1::exporter::otlp::OtlpGrpcMetricExporter::Export(opentelemetry::v1::sdk::metrics::ResourceMetrics const&)':
#0 11.86 otlp_grpc_metric_exporter.cc:(.text+0x10dc): undefined reference to `opentelemetry::proto::collector::metrics::v1::ExportMetricsServiceRequest::ExportMetricsServiceRequest(google::protobuf::Arena*, bool)'
#0 11.86 /usr/lib/gcc/x86_64-alpine-linux-musl/12.2.1/../../../../x86_64-alpine-linux-musl/bin/ld: otlp_grpc_metric_exporter.cc:(.text+0x10ef): undefined reference to `opentelemetry::v1::exporter::otlp::OtlpMetricUtils::PopulateRequest(opentelemetry::v1::sdk::metrics::ResourceMetrics const&, opentelemetry::proto::collector::metrics::v1::ExportMetricsServiceRequest*)'
#0 11.86 /usr/lib/gcc/x86_64-alpine-linux-musl/12.2.1/../../../../x86_64-alpine-linux-musl/bin/ld: otlp_grpc_metric_exporter.cc:(.text+0x110d): undefined reference to `opentelemetry::proto::collector::metrics::v1::ExportMetricsServiceResponse::ExportMetricsServiceResponse(google::protobuf::Arena*, bool)'
#0 11.86 /usr/lib/gcc/x86_64-alpine-linux-musl/12.2.1/../../../../x86_64-alpine-linux-musl/bin/ld: otlp_grpc_metric_exporter.cc:(.text+0x117e): undefined reference to `opentelemetry::proto::collector::metrics::v1::ExportMetricsServiceResponse::~ExportMetricsServiceResponse()'
#0 11.86 /usr/lib/gcc/x86_64-alpine-linux-musl/12.2.1/../../../../x86_64-alpine-linux-musl/bin/ld: otlp_grpc_metric_exporter.cc:(.text+0x11a3): undefined reference to `opentelemetry::proto::collector::metrics::v1::ExportMetricsServiceRequest::~ExportMetricsServiceRequest()'
#0 11.92 collect2: error: ld returned 1 exit status
#0 11.92 make[2]: *** [CMakeFiles/currencyservice.dir/build.make:154: currencyservice] Error 1
#0 11.92 make[1]: *** [CMakeFiles/Makefile2:111: CMakeFiles/currencyservice.dir/all] Error 2
#0 11.92 make: *** [Makefile:136: all] Error 2
------
failed to solve: process "/bin/sh -c cd /currencyservice     && mkdir -p build && cd build     && cmake ..     && make -j$(nproc || sysctl -n hw.ncpu || echo 1) install" did not complete successfully: exit code: 2

Any ideas what am I missing?

[lalitb]

Which platform? I can successfully currencyservice from your branch on ubuntu 20.04.

[julianocosta89]

Oh, really?
You didn't need to change anything?
I can't build it locally on Ubuntu 20.04, maybe I'm still missing some dependencies on my machine.

But the Dockerfile is using Alpine.
Maybe @svrnm also has some thoughts, as he recently changed it.

[lalitb]

Oh, really?
You didn't need to change anything?

Yes for ubuntu. But I had grpc and protobuf already installed on my machine.

But the Dockerfile is using Alpine.

Ok, this could be something similar to #1940 raised by @svrnm, will check on Alpine.

[julianocosta89]

I see 😢
I'll close this ticket and follow the other one.

Thanks for taking a look @lalitb 🤩

[julianocosta89]

@lalitb is the OTLP Metric exporter actually working on release 1.8.2?
Are metrics really GA for OTel C++?

[lalitb]

@julianocosta89 yes it is GA. What issue do you see in OTLP export?

[julianocosta89]

I don't see... That's the issue 😅
I can't build it.

Do I need to use the factory?
I can't find the Create method.
The docs do not say which headers I need to include.
https://opentelemetry.io/docs/instrumentation/cpp/exporters/#otlp-grpc-exporter-1

[julianocosta89]

Tried also the HTTP one, but then I couldn't find the temporality... It was a long day 😕

[lalitb]

Did you follow the example here for gRPC OTLP - https://github.com/open-telemetry/opentelemetry-cpp/blob/main/examples/otlp/grpc_metric_main.cc.

[lalitb]

If these are still the build issues, they should be related to Alpine as it provides binary package for grpc, and we haven't tested this env.

[julianocosta89]

I'll try this out.
I've moved away from Alpine in my local development.
Now I'm using Ubuntu 20.04.

Thx again for the Help @lalitb!

[julianocosta89]

Thanks for the help again @lalitb.
Just sent a PR to the demo repo: open-telemetry/opentelemetry-demo#759