opentelemetry tracer: add Dynatrace resource detector (envoyproxy#30824)

* Add Dynatrace resource detector

Co-authored-by: Thomas Ebner <96168670+samohte@users.noreply.github.com>
Signed-off-by: Joao Grassi <joao.grassi@dynatrace.com>

* PR suggestions

Signed-off-by: Joao Grassi <joao.grassi@dynatrace.com>

* Add tests for Dynatrace file reader

Signed-off-by: Joao Grassi <joao.grassi@dynatrace.com>

* PR suggestions

Signed-off-by: Joao Grassi <joao.grassi@dynatrace.com>

* schemaUrl_ -> schema_url_

Signed-off-by: Joao Grassi <joao.grassi@dynatrace.com>

* PR suggestions and changelog

Signed-off-by: Joao Grassi <joao.grassi@dynatrace.com>

---------

Signed-off-by: Joao Grassi <joao.grassi@dynatrace.com>
Co-authored-by: Thomas Ebner <96168670+samohte@users.noreply.github.com>

Author: joaopgrassi

api/envoy/extensions/tracers/opentelemetry/resource_detectors/v3/dynatrace_resource_detector.proto

@@ -0,0 +1,25 @@
+syntax = "proto3";
+
+package envoy.extensions.tracers.opentelemetry.resource_detectors.v3;
+
+import "udpa/annotations/status.proto";
+
+option java_package = "io.envoyproxy.envoy.extensions.tracers.opentelemetry.resource_detectors.v3";
+option java_outer_classname = "DynatraceResourceDetectorProto";
+option java_multiple_files = true;
+option go_package = "github.com/envoyproxy/go-control-plane/envoy/extensions/tracers/opentelemetry/resource_detectors/v3;resource_detectorsv3";
+option (udpa.annotations.file_status).package_version_status = ACTIVE;
+
+// [#protodoc-title: Dynatrace Resource Detector config]
+
+// Configuration for the Dynatrace Resource Detector extension.
+// The resource detector reads from the Dynatrace enrichment files
+// and adds host/process related attributes to the OpenTelemetry resource.
+//
+// See:
+//
+// `Enrich ingested data with Dynatrace-specific dimensions <https://docs.dynatrace.com/docs/shortlink/enrichment-files>`_
+//
+// [#extension: envoy.tracers.opentelemetry.resource_detectors.dynatrace]
+message DynatraceResourceDetectorConfig {
+}

changelogs/current.yaml

@@ -210,5 +210,8 @@ new_features:
     and
     :ref:`response_attributes <envoy_v3_api_field_extensions.filters.http.ext_proc.v3.ExternalProcessor.response_attributes>`
     config APIs to enable sending and receiving attributes from/to the external processing server.
+- area: tracing
+  change: |
+    Added support to configure a Dynatrace resource detector for the OpenTelemetry tracer.
 
 deprecated:

source/extensions/extensions_build_config.bzl

@@ -271,6 +271,7 @@ EXTENSIONS = {
     #
 
     "envoy.tracers.opentelemetry.resource_detectors.environment":         "//source/extensions/tracers/opentelemetry/resource_detectors/environment:config",
+    "envoy.tracers.opentelemetry.resource_detectors.dynatrace":           "//source/extensions/tracers/opentelemetry/resource_detectors/dynatrace:config",
 
     #
     # OpenTelemetry tracer samplers

source/extensions/extensions_metadata.yaml

@@ -1697,3 +1697,10 @@ envoy.tracers.opentelemetry.resource_detectors.environment:
   status: wip
   type_urls:
   - envoy.extensions.tracers.opentelemetry.resource_detectors.v3.EnvironmentResourceDetectorConfig
+envoy.tracers.opentelemetry.resource_detectors.dynatrace:
+  categories:
+  - envoy.tracers.opentelemetry.resource_detectors
+  security_posture: unknown
+  status: wip
+  type_urls:
+  - envoy.extensions.tracers.opentelemetry.resource_detectors.v3.DynatraceResourceDetectorConfig

source/extensions/tracers/opentelemetry/resource_detectors/dynatrace/BUILD

@@ -0,0 +1,39 @@
+load(
+    "//bazel:envoy_build_system.bzl",
+    "envoy_cc_extension",
+    "envoy_cc_library",
+    "envoy_extension_package",
+)
+
+licenses(["notice"])  # Apache 2
+
+envoy_extension_package()
+
+envoy_cc_extension(
+    name = "config",
+    srcs = ["config.cc"],
+    hdrs = ["config.h"],
+    deps = [
+        ":dynatrace_resource_detector_lib",
+        "//envoy/registry",
+        "//source/common/config:utility_lib",
+        "@envoy_api//envoy/extensions/tracers/opentelemetry/resource_detectors/v3:pkg_cc_proto",
+    ],
+)
+
+envoy_cc_library(
+    name = "dynatrace_resource_detector_lib",
+    srcs = [
+        "dynatrace_metadata_file_reader.cc",
+        "dynatrace_resource_detector.cc",
+    ],
+    hdrs = [
+        "dynatrace_metadata_file_reader.h",
+        "dynatrace_resource_detector.h",
+    ],
+    deps = [
+        "//source/common/config:datasource_lib",
+        "//source/extensions/tracers/opentelemetry/resource_detectors:resource_detector_lib",
+        "@envoy_api//envoy/extensions/tracers/opentelemetry/resource_detectors/v3:pkg_cc_proto",
+    ],
+)

source/extensions/tracers/opentelemetry/resource_detectors/dynatrace/config.cc

@@ -0,0 +1,37 @@
+#include "source/extensions/tracers/opentelemetry/resource_detectors/dynatrace/config.h"
+
+#include "envoy/extensions/tracers/opentelemetry/resource_detectors/v3/dynatrace_resource_detector.pb.h"
+#include "envoy/extensions/tracers/opentelemetry/resource_detectors/v3/dynatrace_resource_detector.pb.validate.h"
+
+#include "source/common/config/utility.h"
+#include "source/extensions/tracers/opentelemetry/resource_detectors/dynatrace/dynatrace_metadata_file_reader.h"
+#include "source/extensions/tracers/opentelemetry/resource_detectors/dynatrace/dynatrace_resource_detector.h"
+
+namespace Envoy {
+namespace Extensions {
+namespace Tracers {
+namespace OpenTelemetry {
+
+ResourceDetectorPtr DynatraceResourceDetectorFactory::createResourceDetector(
+    const Protobuf::Message& message, Server::Configuration::TracerFactoryContext& context) {
+
+  auto mptr = Envoy::Config::Utility::translateAnyToFactoryConfig(
+      dynamic_cast<const ProtobufWkt::Any&>(message), context.messageValidationVisitor(), *this);
+
+  const auto& proto_config = MessageUtil::downcastAndValidate<
+      const envoy::extensions::tracers::opentelemetry::resource_detectors::v3::
+          DynatraceResourceDetectorConfig&>(*mptr, context.messageValidationVisitor());
+
+  DynatraceMetadataFileReaderPtr reader = std::make_unique<DynatraceMetadataFileReaderImpl>();
+  return std::make_unique<DynatraceResourceDetector>(proto_config, std::move(reader));
+}
+
+/**
+ * Static registration for the Dynatrace resource detector factory. @see RegisterFactory.
+ */
+REGISTER_FACTORY(DynatraceResourceDetectorFactory, ResourceDetectorFactory);
+
+} // namespace OpenTelemetry
+} // namespace Tracers
+} // namespace Extensions
+} // namespace Envoy

source/extensions/tracers/opentelemetry/resource_detectors/dynatrace/config.h

@@ -0,0 +1,48 @@
+#pragma once
+
+#include <string>
+
+#include "envoy/extensions/tracers/opentelemetry/resource_detectors/v3/dynatrace_resource_detector.pb.h"
+
+#include "source/extensions/tracers/opentelemetry/resource_detectors/resource_detector.h"
+
+namespace Envoy {
+namespace Extensions {
+namespace Tracers {
+namespace OpenTelemetry {
+
+/**
+ * Config registration for the Dynatrace resource detector. @see ResourceDetectorFactory.
+ */
+class DynatraceResourceDetectorFactory : public ResourceDetectorFactory {
+public:
+  /**
+   * @brief Creates a Resource Detector that reads from the Dynatrace enrichment files.
+   *
+   * @see
+   * https://docs.dynatrace.com/docs/shortlink/enrichment-files#oneagent-virtual-files
+   *
+   * @param message The resource detector configuration.
+   * @param context The tracer factory context.
+   * @return ResourceDetectorPtr
+   */
+  ResourceDetectorPtr
+  createResourceDetector(const Protobuf::Message& message,
+                         Server::Configuration::TracerFactoryContext& context) override;
+
+  ProtobufTypes::MessagePtr createEmptyConfigProto() override {
+    return std::make_unique<envoy::extensions::tracers::opentelemetry::resource_detectors::v3::
+                                DynatraceResourceDetectorConfig>();
+  }
+
+  std::string name() const override {
+    return "envoy.tracers.opentelemetry.resource_detectors.dynatrace";
+  }
+};
+
+DECLARE_FACTORY(DynatraceResourceDetectorFactory);
+
+} // namespace OpenTelemetry
+} // namespace Tracers
+} // namespace Extensions
+} // namespace Envoy

source/extensions/tracers/opentelemetry/resource_detectors/dynatrace/dynatrace_metadata_file_reader.cc

@@ -0,0 +1,54 @@
+#include "source/extensions/tracers/opentelemetry/resource_detectors/dynatrace/dynatrace_metadata_file_reader.h"
+
+#include <fstream>
+#include <iostream>
+#include <sstream>
+#include <string>
+
+#include "envoy/common/exception.h"
+
+#include "source/common/common/logger.h"
+
+#include "absl/strings/str_cat.h"
+
+namespace Envoy {
+namespace Extensions {
+namespace Tracers {
+namespace OpenTelemetry {
+
+namespace {
+
+bool isIndirectionFile(const std::string& file_name) {
+  return absl::StartsWith(file_name, "dt_metadata_");
+}
+
+std::string readFile(const std::string& file_name) {
+  if (file_name.empty()) {
+    return "";
+  }
+
+  std::ifstream file(file_name);
+  if (file.fail()) {
+    throw EnvoyException(absl::StrCat("Unable to read Dynatrace enrichment file: ", file_name));
+  }
+
+  std::stringstream file_string;
+  file_string << file.rdbuf();
+
+  return file_string.str();
+}
+
+} // namespace
+
+std::string DynatraceMetadataFileReaderImpl::readEnrichmentFile(const std::string& file_name) {
+  if (const bool indirection_file = isIndirectionFile(file_name); indirection_file) {
+    return readFile(readFile(file_name));
+  } else {
+    return readFile(file_name);
+  }
+}
+
+} // namespace OpenTelemetry
+} // namespace Tracers
+} // namespace Extensions
+} // namespace Envoy

source/extensions/tracers/opentelemetry/resource_detectors/dynatrace/dynatrace_metadata_file_reader.h

@@ -0,0 +1,49 @@
+#pragma once
+
+#include <array>
+#include <memory>
+#include <string>
+
+#include "envoy/common/pure.h"
+
+#include "absl/strings/match.h"
+
+namespace Envoy {
+namespace Extensions {
+namespace Tracers {
+namespace OpenTelemetry {
+
+/**
+ * @brief A file reader that reads the content of the Dynatrace metadata enrichment files.
+ * When OneAgent is monitoring your application, it provides access to the enrichment files.
+ * These files do not physically exists in your file system, but are provided by the OneAgent on
+ * demand. This allows obtaining not only information about the host, but also about process.
+ *
+ * @see
+ * https://docs.dynatrace.com/docs/shortlink/enrichment-files#oneagent-virtual-files
+ *
+ */
+class DynatraceMetadataFileReader {
+public:
+  virtual ~DynatraceMetadataFileReader() = default;
+
+  /**
+   * @brief Reads the enrichment file and returns the enrichment metadata.
+   *
+   * @param file_name The file name.
+   * @return const std::string String (java-like properties) containing the enrichment metadata.
+   */
+  virtual std::string readEnrichmentFile(const std::string& file_name) PURE;
+};
+
+using DynatraceMetadataFileReaderPtr = std::unique_ptr<DynatraceMetadataFileReader>;
+
+class DynatraceMetadataFileReaderImpl : public DynatraceMetadataFileReader {
+public:
+  std::string readEnrichmentFile(const std::string& file_name) override;
+};
+
+} // namespace OpenTelemetry
+} // namespace Tracers
+} // namespace Extensions
+} // namespace Envoy

source/extensions/tracers/opentelemetry/resource_detectors/dynatrace/dynatrace_resource_detector.cc

@@ -0,0 +1,54 @@
+#include "source/extensions/tracers/opentelemetry/resource_detectors/dynatrace/dynatrace_resource_detector.h"
+
+#include <fstream>
+#include <iostream>
+
+namespace Envoy {
+namespace Extensions {
+namespace Tracers {
+namespace OpenTelemetry {
+namespace {
+
+void addAttributes(const std::string& content, Resource& resource) {
+  for (const auto& line : StringUtil::splitToken(content, "\n", false, true)) {
+    const auto key_value = StringUtil::splitToken(line, "=");
+    if (key_value.size() != 2) {
+      continue;
+    }
+    resource.attributes_[std::string(key_value[0])] = std::string(key_value[1]);
+  }
+}
+
+} // namespace
+
+Resource DynatraceResourceDetector::detect() {
+  Resource resource;
+  resource.schema_url_ = "";
+  int failure_count = 0;
+
+  for (const auto& file_name : DynatraceResourceDetector::dynatraceMetadataFiles()) {
+    TRY_NEEDS_AUDIT {
+      std::string content = dynatrace_file_reader_->readEnrichmentFile(file_name);
+      if (content.empty()) {
+        failure_count++;
+      } else {
+        addAttributes(content, resource);
+      }
+    }
+    END_TRY catch (const EnvoyException&) { failure_count++; }
+  }
+
+  if (failure_count > 0) {
+    ENVOY_LOG(
+        warn,
+        "Dynatrace OpenTelemetry resource detector is configured but could not detect attributes. "
+        "Check the Dynatrace deployment status to ensure it is correctly deployed.");
+  }
+
+  return resource;
+}
+
+} // namespace OpenTelemetry
+} // namespace Tracers
+} // namespace Extensions
+} // namespace Envoy