Feat/dynatrace sampler internal (#11)

Signed-off-by: thomas.ebner <[email protected]>

Signed-off-by: Joao Grassi <[email protected]>

api/envoy/extensions/tracers/opentelemetry/samplers/v3/dynatrace_sampler.proto

@@ -0,0 +1,20 @@
+syntax = "proto3";
+
+package envoy.extensions.tracers.opentelemetry.samplers.v3;
+
+import "udpa/annotations/status.proto";
+
+option java_package = "io.envoyproxy.envoy.extensions.tracers.opentelemetry.samplers.v3";
+option java_outer_classname = "DynatraceSamplerProto";
+option java_multiple_files = true;
+option go_package = "github.com/envoyproxy/go-control-plane/envoy/extensions/tracers/opentelemetry/samplers/v3;samplersv3";
+option (udpa.annotations.file_status).package_version_status = ACTIVE;
+
+// [#protodoc-title: Dynatrace Sampler config]
+// [#extension: envoy.tracers.opentelemetry.samplers.dynatrace]
+
+message DynatraceSamplerConfig {
+  string tenant_id = 1;
+
+  string cluster_id = 2;
+}

source/extensions/extensions_build_config.bzl

@@ -279,6 +279,7 @@ EXTENSIONS = {
     #
 
     "envoy.tracers.opentelemetry.samplers.always_on":         "//source/extensions/tracers/opentelemetry/samplers/always_on:config",
+    "envoy.tracers.opentelemetry.samplers.dynatrace":         "//source/extensions/tracers/opentelemetry/samplers/dynatrace:config",
 
     #
     # Transport sockets

source/extensions/extensions_metadata.yaml

@@ -1180,6 +1180,13 @@ envoy.tracers.opentelemetry.samplers.always_on:
   status: wip
   type_urls:
   - envoy.extensions.tracers.opentelemetry.samplers.v3.AlwaysOnSamplerConfig
+envoy.tracers.opentelemetry.samplers.dynatrace:
+  categories:
+  - envoy.tracers.opentelemetry.samplers
+  security_posture: unknown
+  status: wip
+  type_urls:
+  - envoy.extensions.tracers.opentelemetry.samplers.v3.DynatraceSamplerConfig
 envoy.tracers.skywalking:
   categories:
   - envoy.tracers

source/extensions/tracers/opentelemetry/samplers/dynatrace/BUILD

@@ -0,0 +1,42 @@
+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_sampler_lib",
+        "//envoy/registry",
+        "//source/common/config:utility_lib",
+        "@envoy_api//envoy/extensions/tracers/opentelemetry/samplers/v3:pkg_cc_proto",
+    ],
+)
+
+envoy_cc_library(
+    name = "dynatrace_sampler_lib",
+    srcs = [
+        "dynatrace_sampler.cc",
+        "dynatrace_tracestate.cc",
+        "tracestate.cc",
+    ],
+    hdrs = [
+        "dynatrace_sampler.h",
+        "dynatrace_tracestate.h",
+        "tracestate.h",
+    ],
+    deps = [
+        "//source/common/config:datasource_lib",
+        "//source/extensions/tracers/opentelemetry:opentelemetry_tracer_lib",
+        "//source/extensions/tracers/opentelemetry/samplers:sampler_lib",
+        "@envoy_api//envoy/extensions/tracers/opentelemetry/samplers/v3:pkg_cc_proto",
+    ],
+)

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

@@ -0,0 +1,34 @@
+#include "config.h"
+
+#include "envoy/extensions/tracers/opentelemetry/samplers/v3/dynatrace_sampler.pb.validate.h"
+
+#include "source/common/config/utility.h"
+#include "source/common/protobuf/utility.h"
+#include "source/extensions/tracers/opentelemetry/samplers/dynatrace/dynatrace_sampler.h"
+
+namespace Envoy {
+namespace Extensions {
+namespace Tracers {
+namespace OpenTelemetry {
+
+SamplerSharedPtr
+DynatraceSamplerFactory::createSampler(const Protobuf::Message& config,
+                                       Server::Configuration::TracerFactoryContext& context) {
+  auto mptr = Envoy::Config::Utility::translateAnyToFactoryConfig(
+      dynamic_cast<const ProtobufWkt::Any&>(config), context.messageValidationVisitor(), *this);
+  return std::make_shared<DynatraceSampler>(
+      MessageUtil::downcastAndValidate<
+          const envoy::extensions::tracers::opentelemetry::samplers::v3::DynatraceSamplerConfig&>(
+          *mptr, context.messageValidationVisitor()),
+      context);
+}
+
+/**
+ * Static registration for the Env sampler factory. @see RegisterFactory.
+ */
+REGISTER_FACTORY(DynatraceSamplerFactory, SamplerFactory);
+
+} // namespace OpenTelemetry
+} // namespace Tracers
+} // namespace Extensions
+} // namespace Envoy

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

@@ -0,0 +1,41 @@
+#pragma once
+
+#include <string>
+
+#include "envoy/extensions/tracers/opentelemetry/samplers/v3/dynatrace_sampler.pb.h"
+#include "envoy/registry/registry.h"
+
+#include "source/extensions/tracers/opentelemetry/samplers/sampler.h"
+
+namespace Envoy {
+namespace Extensions {
+namespace Tracers {
+namespace OpenTelemetry {
+
+/**
+ * Config registration for the DynatraceSampler. @see SamplerFactory.
+ */
+class DynatraceSamplerFactory : public SamplerFactory {
+public:
+  /**
+   * @brief Create a Sampler which samples every span
+   *
+   * @param context
+   * @return SamplerSharedPtr
+   */
+  SamplerSharedPtr createSampler(const Protobuf::Message& config,
+                                 Server::Configuration::TracerFactoryContext& context) override;
+
+  ProtobufTypes::MessagePtr createEmptyConfigProto() override {
+    return std::make_unique<
+        envoy::extensions::tracers::opentelemetry::samplers::v3::DynatraceSamplerConfig>();
+  }
+  std::string name() const override { return "envoy.tracers.opentelemetry.samplers.dynatrace"; }
+};
+
+DECLARE_FACTORY(DynatraceSamplerFactory);
+
+} // namespace OpenTelemetry
+} // namespace Tracers
+} // namespace Extensions
+} // namespace Envoy

source/extensions/tracers/opentelemetry/samplers/dynatrace/dynatrace_sampler.cc

@@ -0,0 +1,88 @@
+#include "source/extensions/tracers/opentelemetry/samplers/dynatrace/dynatrace_sampler.h"
+
+#include <memory>
+#include <sstream>
+#include <string>
+
+#include "source/common/config/datasource.h"
+#include "source/extensions/tracers/opentelemetry/samplers/dynatrace/dynatrace_tracestate.h"
+#include "source/extensions/tracers/opentelemetry/samplers/dynatrace/tracestate.h"
+#include "source/extensions/tracers/opentelemetry/samplers/sampler.h"
+#include "source/extensions/tracers/opentelemetry/span_context.h"
+
+namespace Envoy {
+namespace Extensions {
+namespace Tracers {
+namespace OpenTelemetry {
+
+static const char* SAMPLING_EXTRAPOLATION_SPAN_ATTRIBUTE_NAME =
+    "sampling_extrapolation_set_in_sampler";
+
+FW4Tag DynatraceSampler::getFW4Tag(const Tracestate& tracestate) {
+  for (auto const& entry : tracestate.entries()) {
+    if (dt_tracestate_entry_.keyMatches(
+            entry.key)) { // found a tracestate entry with key matching our tenant/cluster
+      return FW4Tag::create(entry.value);
+    }
+  }
+  return FW4Tag::createInvalid();
+}
+
+DynatraceSampler::DynatraceSampler(
+    const envoy::extensions::tracers::opentelemetry::samplers::v3::DynatraceSamplerConfig& config,
+    Server::Configuration::TracerFactoryContext& /*context*/)
+    : tenant_id_(config.tenant_id()), cluster_id_(config.cluster_id()),
+      dt_tracestate_entry_(tenant_id_, cluster_id_), counter_(0) {}
+
+SamplingResult DynatraceSampler::shouldSample(const absl::optional<SpanContext> parent_context,
+                                              const std::string& /*trace_id*/,
+                                              const std::string& /*name*/, OTelSpanKind /*kind*/,
+                                              OptRef<const Tracing::TraceContext> /*trace_context*/,
+                                              const std::vector<SpanContext>& /*links*/) {
+
+  SamplingResult result;
+  std::map<std::string, std::string> att;
+  // search for an existing forward tag in the tracestate
+  Tracestate tracestate;
+  tracestate.parse(parent_context.has_value() ? parent_context->tracestate() : "");
+
+  if (FW4Tag fw4_tag = getFW4Tag(tracestate);
+      fw4_tag.isValid()) { // we found a trace decision in tracestate header
+    result.decision = fw4_tag.isIgnored() ? Decision::DROP : Decision::RECORD_AND_SAMPLE;
+    att[SAMPLING_EXTRAPOLATION_SPAN_ATTRIBUTE_NAME] = std::to_string(fw4_tag.getSamplingExponent());
+    result.tracestate = parent_context->tracestate();
+
+  } else { // make a sampling decision
+    // this is just a demo, we sample every second request here
+    uint32_t current_counter = ++counter_;
+    bool sample;
+    int sampling_exponent;
+    if (current_counter % 2) {
+      sample = true;
+      sampling_exponent = 1;
+    } else {
+      sample = false;
+      sampling_exponent = 0;
+    }
+
+    att[SAMPLING_EXTRAPOLATION_SPAN_ATTRIBUTE_NAME] = std::to_string(sampling_exponent);
+
+    result.decision = sample ? Decision::RECORD_AND_SAMPLE : Decision::DROP;
+    // create new forward tag and add it to tracestate
+    FW4Tag new_tag = FW4Tag::create(!sample, sampling_exponent);
+    tracestate.add(dt_tracestate_entry_.getKey(), new_tag.asString());
+    result.tracestate = tracestate.asString();
+  }
+
+  if (!att.empty()) {
+    result.attributes = std::make_unique<const std::map<std::string, std::string>>(std::move(att));
+  }
+  return result;
+}
+
+std::string DynatraceSampler::getDescription() const { return "DynatraceSampler"; }
+
+} // namespace OpenTelemetry
+} // namespace Tracers
+} // namespace Extensions
+} // namespace Envoy

source/extensions/tracers/opentelemetry/samplers/dynatrace/dynatrace_sampler.h

@@ -0,0 +1,45 @@
+#pragma once
+
+#include "envoy/extensions/tracers/opentelemetry/samplers/v3/dynatrace_sampler.pb.h"
+#include "envoy/server/factory_context.h"
+
+#include "source/common/common/logger.h"
+#include "source/common/config/datasource.h"
+#include "source/extensions/tracers/opentelemetry/samplers/dynatrace/dynatrace_tracestate.h"
+#include "source/extensions/tracers/opentelemetry/samplers/dynatrace/tracestate.h"
+#include "source/extensions/tracers/opentelemetry/samplers/sampler.h"
+
+namespace Envoy {
+namespace Extensions {
+namespace Tracers {
+namespace OpenTelemetry {
+
+/**
+ * @brief A Dynatrace specific sampler *
+ */
+class DynatraceSampler : public Sampler, Logger::Loggable<Logger::Id::tracing> {
+public:
+  DynatraceSampler(
+      const envoy::extensions::tracers::opentelemetry::samplers::v3::DynatraceSamplerConfig& config,
+      Server::Configuration::TracerFactoryContext& context);
+
+  SamplingResult shouldSample(const absl::optional<SpanContext> parent_context,
+                              const std::string& trace_id, const std::string& name,
+                              OTelSpanKind spankind,
+                              OptRef<const Tracing::TraceContext> trace_context,
+                              const std::vector<SpanContext>& links) override;
+
+  std::string getDescription() const override;
+
+private:
+  std::string tenant_id_;
+  std::string cluster_id_;
+  DtTracestateEntry dt_tracestate_entry_;
+  std::atomic<uint32_t> counter_; // request counter for dummy sampling
+  FW4Tag getFW4Tag(const Tracestate& tracestate);
+};
+
+} // namespace OpenTelemetry
+} // namespace Tracers
+} // namespace Extensions
+} // namespace Envoy

source/extensions/tracers/opentelemetry/samplers/dynatrace/dynatrace_tracestate.cc

@@ -0,0 +1,46 @@
+#include "source/extensions/tracers/opentelemetry/samplers/dynatrace/dynatrace_tracestate.h"
+
+#include <string>
+#include <vector>
+
+#include "absl/strings/match.h"
+#include "absl/strings/str_cat.h"
+#include "absl/strings/str_split.h"
+#include "absl/strings/string_view.h"
+
+namespace Envoy {
+namespace Extensions {
+namespace Tracers {
+namespace OpenTelemetry {
+
+FW4Tag FW4Tag::createInvalid() { return {false, false, 0}; }
+
+FW4Tag FW4Tag::create(bool ignored, int sampling_exponent) {
+  return {true, ignored, sampling_exponent};
+}
+
+FW4Tag FW4Tag::create(const std::string& value) {
+  std::vector<absl::string_view> tracestate_components =
+      absl::StrSplit(value, ';', absl::AllowEmpty());
+  if (tracestate_components.size() < 7) {
+    return createInvalid();
+  }
+
+  if (tracestate_components[0] != "fw4") {
+    return createInvalid();
+  }
+  bool ignored = tracestate_components[5] == "1";
+  int sampling_exponent = std::stoi(std::string(tracestate_components[6]));
+  return {true, ignored, sampling_exponent};
+}
+
+std::string FW4Tag::asString() const {
+  std::string ret =
+      absl::StrCat("fw4;0;0;0;0;", ignored_ ? "1" : "0", ";", sampling_exponent_, ";0");
+  return ret;
+}
+
+} // namespace OpenTelemetry
+} // namespace Tracers
+} // namespace Extensions
+} // namespace Envoy

source/extensions/tracers/opentelemetry/samplers/dynatrace/dynatrace_tracestate.h

@@ -0,0 +1,53 @@
+#pragma once
+
+#include <string>
+
+#include "absl/strings/str_cat.h"
+#include "absl/strings/string_view.h"
+
+namespace Envoy {
+namespace Extensions {
+namespace Tracers {
+namespace OpenTelemetry {
+
+class FW4Tag {
+public:
+  static FW4Tag createInvalid();
+
+  static FW4Tag create(bool ignored, int sampling_exponent);
+
+  static FW4Tag create(const std::string& value);
+
+  std::string asString() const;
+
+  bool isValid() const { return valid_; };
+  bool isIgnored() const { return ignored_; };
+  int getSamplingExponent() const { return sampling_exponent_; };
+
+private:
+  FW4Tag(bool valid, bool ignored, int sampling_exponent)
+      : valid_(valid), ignored_(ignored), sampling_exponent_(sampling_exponent) {}
+
+  bool valid_;
+  bool ignored_;
+  int sampling_exponent_;
+};
+
+// <tenantID>-<clusterID>@dt=fw4;0;0;0;0;<isIgnored>;<sampling_exponent>;<rootPathRandom>
+class DtTracestateEntry {
+public:
+  DtTracestateEntry(const std::string& tenant_id, const std::string& cluster_id) {
+    key_ = absl::StrCat(absl::string_view(tenant_id), "-", absl::string_view(cluster_id), "@dt");
+  }
+
+  std::string getKey() const { return key_; };
+
+  bool keyMatches(const std::string& key) { return (key_.compare(key) == 0); }
+
+private:
+  std::string key_;
+};
+} // namespace OpenTelemetry
+} // namespace Tracers
+} // namespace Extensions
+} // namespace Envoy