Allow specifying samplers for the OpenTelemetry tracer via a new configuration. (#30259)

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

Mirrored from https://github.com/envoyproxy/envoy @ c600637b9fddfe3f1381baf436e050f3fa7723b6

BUILD

@@ -307,6 +307,7 @@ proto_library(
         "//envoy/extensions/stat_sinks/open_telemetry/v3:pkg",
         "//envoy/extensions/stat_sinks/wasm/v3:pkg",
         "//envoy/extensions/tracers/opentelemetry/resource_detectors/v3:pkg",
+        "//envoy/extensions/tracers/opentelemetry/samplers/v3:pkg",
         "//envoy/extensions/transport_sockets/alts/v3:pkg",
         "//envoy/extensions/transport_sockets/http_11_proxy/v3:pkg",
         "//envoy/extensions/transport_sockets/internal_upstream/v3:pkg",

envoy/config/trace/v3/opentelemetry.proto

@@ -19,6 +19,7 @@ option (udpa.annotations.file_status).package_version_status = ACTIVE;
 
 // Configuration for the OpenTelemetry tracer.
 //  [#extension: envoy.tracers.opentelemetry]
+// [#next-free-field: 6]
 message OpenTelemetryConfig {
   // The upstream gRPC cluster that will receive OTLP traces.
   // Note that the tracer drops traces if the server does not read data fast enough.
@@ -48,4 +49,12 @@ message OpenTelemetryConfig {
   // An ordered list of resource detectors
   // [#extension-category: envoy.tracers.opentelemetry.resource_detectors]
   repeated core.v3.TypedExtensionConfig resource_detectors = 4;
+
+  // Specifies the sampler to be used by the OpenTelemetry tracer.
+  // The configured sampler implements the Sampler interface defined by the OpenTelemetry specification.
+  // This field can be left empty. In this case, the default Envoy sampling decision is used.
+  //
+  // See: `OpenTelemetry sampler specification <https://opentelemetry.io/docs/specs/otel/trace/sdk/#sampler>`_
+  // [#extension-category: envoy.tracers.opentelemetry.samplers]
+  core.v3.TypedExtensionConfig sampler = 5;
 }

envoy/extensions/tracers/opentelemetry/samplers/v3/BUILD

@@ -0,0 +1,9 @@
+# DO NOT EDIT. This file is generated by tools/proto_format/proto_sync.py.
+
+load("@envoy_api//bazel:api_build_system.bzl", "api_proto_package")
+
+licenses(["notice"])  # Apache 2
+
+api_proto_package(
+    deps = ["@com_github_cncf_udpa//udpa/annotations:pkg"],
+)

envoy/extensions/tracers/opentelemetry/samplers/v3/always_on_sampler.proto

@@ -0,0 +1,23 @@
+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 = "AlwaysOnSamplerProto";
+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: Always On Sampler config]
+// Configuration for the "AlwaysOn" Sampler extension.
+// The sampler follows the "AlwaysOn" implementation from the OpenTelemetry
+// SDK specification.
+//
+// See:
+// `AlwaysOn sampler specification <https://opentelemetry.io/docs/specs/otel/trace/sdk/#alwayson>`_
+// [#extension: envoy.tracers.opentelemetry.samplers.always_on]
+
+message AlwaysOnSamplerConfig {
+}

versioning/BUILD

@@ -246,6 +246,7 @@ proto_library(
         "//envoy/extensions/stat_sinks/open_telemetry/v3:pkg",
         "//envoy/extensions/stat_sinks/wasm/v3:pkg",
         "//envoy/extensions/tracers/opentelemetry/resource_detectors/v3:pkg",
+        "//envoy/extensions/tracers/opentelemetry/samplers/v3:pkg",
         "//envoy/extensions/transport_sockets/alts/v3:pkg",
         "//envoy/extensions/transport_sockets/http_11_proxy/v3:pkg",
         "//envoy/extensions/transport_sockets/internal_upstream/v3:pkg",