Populate resource to OTLP proto data

.markdownlintignore

@@ -1,2 +1,3 @@
 third_party/**
 tools/**
+examples/otlp/README.md

CHANGELOG.md

@@ -15,6 +15,8 @@ Increment the:
 
 ## [Unreleased]
 
+* [EXPORTER] Populate resource to OTLP proto data ([#758](https://github.com/open-telemetry/opentelemetry-cpp/pull/758))
+
 ## [0.6.0] 2021-05-11
 
 * [EXPORTER] Add Jaeger exporter ([#534](https://github.com/open-telemetry/opentelemetry-cpp/pull/534))

examples/otlp/README.md

@@ -10,36 +10,34 @@ SDK](https://github.com/open-telemetry/opentelemetry-cpp). The application then
 calls a `foo_library` which has been instrumented using the [OpenTelemetry
 API](https://github.com/open-telemetry/opentelemetry-cpp/tree/main/api).
 
-To enable TLS authentication for OTLP grpc exporter, SslCredentials can be used by
-specifying the path to client certificate pem file, or the string containing this certificate via OtlpExporterOptions. The path to such a
-.pem file can be provided as a command-line argument alongwith the collector endpoint
-to the main binary invocation above.
+To enable TLS authentication for OTLP grpc exporter, SslCredentials can be used
+by specifying the path to client certificate pem file, or the string containing
+this certificate via OtlpExporterOptions. The path to such a .pem file can be
+provided as a command-line argument alongwith the collector endpoint to the main
+binary invocation above.
 
 Resulting spans are exported to the **OpenTelemetry Collector** using the OTLP
 exporter. The OpenTelemetry Collector can be configured to export to other
 backends (see list of [supported
 backends](https://github.com/open-telemetry/opentelemetry-collector/blob/main/exporter/README.md)).
 
-For instructions on downloading and running the OpenTelemetry Collector, see
-[Getting Started](https://opentelemetry.io/docs/collector/about/).
-
-Here is an example of a Collector `config.yaml` file that can be used to export
-to [Zipkin](https://zipkin.io/) via the Collector using the OTLP exporter:
-
-```yml
-receivers:
-  otlp:
-    protocols:
-      grpc:
-        endpoint: localhost:4317
-exporters:
-  zipkin:
-    endpoint: "http://localhost:9411/api/v2/spans"
-service:
-  pipelines:
-    traces:
-      receivers: [otlp]
-      exporters: [zipkin]
+Follow below command to run the **OpenTelemetry Collector** with OTLP receiver
+in docker which dumps the received data into console. See [Getting
+Started](https://opentelemetry.io/docs/collector/about/) for more information.
+
+Open a terminal window at the root directory of this repo and launch the
+OpenTelemetry Collector with an OTLP receiver by running:
+
+- On Unix based systems use:
+
+```console
+docker run --rm -it -p 4317:4317 -v $(pwd)/examples/otlp:/cfg otel/opentelemetry-collector:0.19.0 --config=/cfg/opentelemetry-collector-config/config.dev.yaml
+```
+
+- On Windows use:
+
+```console
+docker run --rm -it -p 4317:4317 -v "%cd%/examples/otlp":/cfg otel/opentelemetry-collector:0.19.0 --config=/cfg/opentelemetry-collector-config/config.dev.yaml
 ```
 
 Note that the OTLP exporter connects to the Collector at `localhost:4317` by

examples/otlp/opentelemetry-collector-config/config.dev.yaml

@@ -0,0 +1,15 @@
+exporters:
+  logging:
+    loglevel: DEBUG
+receivers:
+  otlp:
+    protocols:
+      grpc:
+        endpoint: 0.0.0.0:4317
+service:
+  pipelines:
+    traces:
+      receivers:
+      - otlp
+      exporters:
+      - logging

exporters/otlp/include/opentelemetry/exporters/otlp/recordable.h

@@ -20,7 +20,7 @@ class Recordable final : public sdk::trace::Recordable
   const proto::trace::v1::Span &span() const noexcept { return span_; }
 
   /** Dynamically converts the resource of this span into a proto. */
-  proto::resource::v1::Resource ProtoResource() const noexcept;
+  void PopulateProtoResource(proto::resource::v1::Resource *resource) const noexcept;
 
   void SetIdentity(const opentelemetry::trace::SpanContext &span_context,
                    opentelemetry::trace::SpanId parent_span_id) noexcept override;
@@ -53,7 +53,7 @@ class Recordable final : public sdk::trace::Recordable
 
 private:
   proto::trace::v1::Span span_;
-  const opentelemetry::sdk::resource::Resource *resource_;
+  const opentelemetry::sdk::resource::Resource *resource_ = nullptr;
 };
 }  // namespace otlp
 }  // namespace exporter

exporters/otlp/src/otlp_exporter.cc

@@ -28,8 +28,18 @@ void PopulateRequest(const nostd::span<std::unique_ptr<sdk::trace::Recordable>>
   for (auto &recordable : spans)
   {
     auto rec = std::unique_ptr<Recordable>(static_cast<Recordable *>(recordable.release()));
-    // TODO - Handle Resource
     *instrumentation_lib->add_spans() = std::move(rec->span());
+
+    if (!has_resource)
+    {
+      std::unique_ptr<proto::resource::v1::Resource> proto_resource{
+          new proto::resource::v1::Resource};
+
+      rec->PopulateProtoResource(proto_resource.get());
+
+      resource_span->set_allocated_resource(proto_resource.release());
+      has_resource = true;
+    }
   }
 }
 

exporters/otlp/src/recordable.cc

@@ -216,17 +216,15 @@ void PopulateAttribute(opentelemetry::proto::common::v1::KeyValue *attribute,
   }
 }
 
-proto::resource::v1::Resource Recordable::ProtoResource() const noexcept
+void Recordable::PopulateProtoResource(proto::resource::v1::Resource *proto) const noexcept
 {
-  proto::resource::v1::Resource proto;
   if (resource_)
   {
     for (const auto &kv : resource_->GetAttributes())
     {
-      PopulateAttribute(proto.add_attributes(), kv.first, kv.second);
+      PopulateAttribute(proto->add_attributes(), kv.first, kv.second);
     }
   }
-  return proto;
 }
 
 void Recordable::SetResource(const opentelemetry::sdk::resource::Resource &resource) noexcept