ORCA: Added utility methods to parse ORCA response headers from backe…

…nds. (#35422)

Signed-off-by: blake-snyder <blakesnyder@google.com>

source/common/orca/BUILD

@@ -0,0 +1,25 @@
+load(
+    "//bazel:envoy_build_system.bzl",
+    "envoy_cc_library",
+    "envoy_package",
+)
+
+licenses(["notice"])  # Apache 2
+
+envoy_package()
+
+envoy_cc_library(
+    name = "orca_parser",
+    srcs = ["orca_parser.cc"],
+    hdrs = ["orca_parser.h"],
+    external_deps = [
+        "abseil_strings",
+        "abseil_statusor",
+        "fmtlib",
+    ],
+    deps = [
+        "//envoy/http:header_map_interface",
+        "//source/common/common:base64_lib",
+        "@com_github_cncf_xds//xds/data/orca/v3:pkg_cc_proto",
+    ],
+)

source/common/orca/orca_parser.cc

@@ -0,0 +1,45 @@
+#include "source/common/orca/orca_parser.h"
+
+#include <string>
+
+#include "envoy/http/header_map.h"
+
+#include "source/common/common/base64.h"
+#include "source/common/common/fmt.h"
+
+#include "absl/strings/string_view.h"
+
+using ::Envoy::Http::HeaderMap;
+using xds::data::orca::v3::OrcaLoadReport;
+
+namespace Envoy {
+namespace Orca {
+
+namespace {
+
+const Http::LowerCaseString& endpointLoadMetricsHeaderBin() {
+  CONSTRUCT_ON_FIRST_USE(Http::LowerCaseString, kEndpointLoadMetricsHeaderBin);
+}
+
+} // namespace
+
+absl::StatusOr<OrcaLoadReport> parseOrcaLoadReportHeaders(const HeaderMap& headers) {
+  OrcaLoadReport load_report;
+
+  // Binary protobuf format.
+  if (const auto header_bin = headers.get(endpointLoadMetricsHeaderBin()); !header_bin.empty()) {
+    const auto header_value = header_bin[0]->value().getStringView();
+    const std::string decoded_value = Envoy::Base64::decode(header_value);
+    if (!load_report.ParseFromString(decoded_value)) {
+      return absl::InvalidArgumentError(
+          fmt::format("unable to parse binaryheader to OrcaLoadReport: {}", header_value));
+    }
+  } else {
+    return absl::NotFoundError("no ORCA data sent from the backend");
+  }
+
+  return load_report;
+}
+
+} // namespace Orca
+} // namespace Envoy

source/common/orca/orca_parser.h

@@ -0,0 +1,19 @@
+#pragma once
+
+#include "envoy/http/header_map.h"
+
+#include "absl/status/statusor.h"
+#include "xds/data/orca/v3/orca_load_report.pb.h"
+
+namespace Envoy {
+namespace Orca {
+
+// Header used to send ORCA load metrics from the backend.
+static constexpr absl::string_view kEndpointLoadMetricsHeaderBin = "endpoint-load-metrics-bin";
+
+// Parses ORCA load metrics from a header map into an OrcaLoadReport proto.
+// Supports serialized binary formats.
+absl::StatusOr<xds::data::orca::v3::OrcaLoadReport>
+parseOrcaLoadReportHeaders(const Envoy::Http::HeaderMap& headers);
+} // namespace Orca
+} // namespace Envoy

test/common/orca/BUILD

@@ -0,0 +1,26 @@
+load(
+    "//bazel:envoy_build_system.bzl",
+    "envoy_cc_test",
+    "envoy_package",
+)
+
+licenses(["notice"])  # Apache 2
+
+envoy_package()
+
+envoy_cc_test(
+    name = "orca_parser_test",
+    srcs = ["orca_parser_test.cc"],
+    external_deps = [
+        "abseil_status",
+        "abseil_strings",
+        "fmtlib",
+    ],
+    deps = [
+        "//source/common/common:base64_lib",
+        "//source/common/orca:orca_parser",
+        "//test/test_common:status_utility_lib",
+        "//test/test_common:utility_lib",
+        "@com_github_cncf_xds//xds/data/orca/v3:pkg_cc_proto",
+    ],
+)

test/common/orca/orca_parser_test.cc

@@ -0,0 +1,72 @@
+#include <string>
+
+#include "source/common/common/base64.h"
+#include "source/common/orca/orca_parser.h"
+
+#include "test/test_common/status_utility.h"
+#include "test/test_common/utility.h"
+
+#include "absl/status/status.h"
+#include "xds/data/orca/v3/orca_load_report.pb.h"
+
+namespace Envoy {
+namespace Orca {
+namespace {
+
+// Returns an example OrcaLoadReport proto with all fields populated.
+static xds::data::orca::v3::OrcaLoadReport exampleOrcaLoadReport() {
+  xds::data::orca::v3::OrcaLoadReport orca_load_report;
+  orca_load_report.set_cpu_utilization(0.7);
+  orca_load_report.set_application_utilization(0.8);
+  orca_load_report.set_mem_utilization(0.9);
+  orca_load_report.set_eps(2);
+  orca_load_report.set_rps_fractional(1000);
+  orca_load_report.mutable_named_metrics()->insert({"foo", 123});
+  orca_load_report.mutable_named_metrics()->insert({"bar", 0.2});
+  return orca_load_report;
+}
+
+TEST(OrcaParserUtilTest, NoHeaders) {
+  Http::TestRequestHeaderMapImpl headers{};
+  // parseOrcaLoadReport returns error when no ORCA data is sent from
+  // the backend.
+  EXPECT_THAT(parseOrcaLoadReportHeaders(headers),
+              StatusHelpers::HasStatus(absl::NotFoundError("no ORCA data sent from the backend")));
+}
+
+TEST(OrcaParserUtilTest, MissingOrcaHeaders) {
+  Http::TestRequestHeaderMapImpl headers{{"wrong-header", "wrong-value"}};
+  // parseOrcaLoadReport returns error when no ORCA data is sent from
+  // the backend.
+  EXPECT_THAT(parseOrcaLoadReportHeaders(headers),
+              StatusHelpers::HasStatus(absl::NotFoundError("no ORCA data sent from the backend")));
+}
+
+TEST(OrcaParserUtilTest, BinaryHeader) {
+  const std::string proto_string =
+      TestUtility::getProtobufBinaryStringFromMessage(exampleOrcaLoadReport());
+  const auto orca_load_report_header_bin =
+      Envoy::Base64::encode(proto_string.c_str(), proto_string.length());
+  Http::TestRequestHeaderMapImpl headers{
+      {std::string(kEndpointLoadMetricsHeaderBin), orca_load_report_header_bin}};
+  EXPECT_THAT(parseOrcaLoadReportHeaders(headers),
+              StatusHelpers::IsOkAndHolds(ProtoEq(exampleOrcaLoadReport())));
+}
+
+TEST(OrcaParserUtilTest, InvalidBinaryHeader) {
+  const std::string proto_string =
+      TestUtility::getProtobufBinaryStringFromMessage(exampleOrcaLoadReport());
+  // Force a bad base64 encoding by shortening the length of the output.
+  const auto orca_load_report_header_bin =
+      Envoy::Base64::encode(proto_string.c_str(), proto_string.length() / 2);
+  Http::TestRequestHeaderMapImpl headers{
+      {std::string(kEndpointLoadMetricsHeaderBin), orca_load_report_header_bin}};
+  EXPECT_THAT(parseOrcaLoadReportHeaders(headers),
+              StatusHelpers::HasStatus(
+                  absl::StatusCode::kInvalidArgument,
+                  testing::HasSubstr("unable to parse binaryheader to OrcaLoadReport")));
+}
+
+} // namespace
+} // namespace Orca
+} // namespace Envoy