Add a User-Agent header to metadata API requests; allow overriding via config; add --version argument.

src/Makefile

@@ -1,3 +1,7 @@
+PKG_VERSION=0.0.17
+PKG_RELEASE=1
+DOCKER_VERSION=0.2
+
 LIBDIR=../lib
 CPP_NETLIB_DIR=$(LIBDIR)/cpp-netlib
 CPP_NETLIB_LIBDIR=$(CPP_NETLIB_DIR)/libs/network/src
@@ -9,10 +13,12 @@ SUBMODULE_DIRS=$(CPP_NETLIB_DIR) $(YAML_CPP_DIR)
 
 SED_I=/usr/bin/env sed -i
 CMAKE=cmake
-CXXFLAGS=\
-    -std=c++11 -g -Wno-write-strings -Wno-deprecated \
+CPPFLAGS=\
+    -DAGENT_VERSION='$(PKG_VERSION)-$(PKG_RELEASE)' \
     -DENABLE_DOCKER_METADATA -DENABLE_KUBERNETES_METADATA \
     -I$(CPP_NETLIB_DIR) -I$(NETWORK_URI_DIR)/include -I$(YAML_CPP_DIR)/include
+CXXFLAGS=\
+    -std=c++11 -g -Wno-write-strings -Wno-deprecated
 LDFLAGS=-L$(CPP_NETLIB_LIBDIR) -L$(NETWORK_URI_LIBDIR) -L$(YAML_CPP_LIBDIR)
 LDLIBS=\
     -lcppnetlib-client-connections -lcppnetlib-server-parsers -lnetwork-uri \
@@ -77,11 +83,8 @@ install: metadatad
 
 export DISTRO
 PKG_NAME=stackdriver-metadata
-PKG_VERSION=0.0.17
-PKG_RELEASE=1
 PKG_MAINTAINER=Stackdriver Agents <stackdriver-agents@google.com>
 
-DOCKER_VERSION=0.2
 DOCKER_IMAGE=us.gcr.io/container-monitoring-storage/stackdriver-metadata-agent
 DOCKER_TAG=$(DOCKER_VERSION)-$(PKG_VERSION)-$(PKG_RELEASE)
 

src/api_server.cc

@@ -192,6 +192,7 @@ namespace {
 void SendMetadataRequest(std::vector<json::value>&& entries,
                          const std::string& endpoint,
                          const std::string& auth_header,
+                         const std::string& user_agent,
                          bool verbose_logging)
     throw (boost::system::system_error) {
   json::value update_metadata_request = json::object({
@@ -200,12 +201,14 @@ void SendMetadataRequest(std::vector<json::value>&& entries,
 
   if (verbose_logging) {
     LOG(INFO) << "About to send request: POST " << endpoint
+              << " User-Agent: " << user_agent
               << " " << *update_metadata_request;
   }
 
   http::client client;
   http::client::request request(endpoint);
   std::string request_body = update_metadata_request->ToString();
+  request << boost::network::header("User-Agent", user_agent);
   request << boost::network::header("Content-Length",
                                     std::to_string(request_body.size()));
   request << boost::network::header("Content-Type", "application/json");
@@ -247,6 +250,7 @@ void MetadataReporter::SendMetadata(
       format::Substitute(agent_->config_.MetadataIngestionEndpointFormat(),
                          {{"project_id", project_id}});
   const std::string auth_header = auth_.GetAuthHeaderValue();
+  const std::string user_agent = agent_->config_.MetadataReporterUserAgent();
 
   const json::value empty_request = json::object({
     {"entries", json::array({})},
@@ -282,7 +286,7 @@ void MetadataReporter::SendMetadata(
       continue;
     }
     if (total_size + size > limit_bytes) {
-      SendMetadataRequest(std::move(entries), endpoint, auth_header,
+      SendMetadataRequest(std::move(entries), endpoint, auth_header, user_agent,
                           agent_->config_.VerboseLogging());
       entries.clear();
       total_size = empty_size;
@@ -291,7 +295,7 @@ void MetadataReporter::SendMetadata(
     total_size += size;
   }
   if (!entries.empty()) {
-    SendMetadataRequest(std::move(entries), endpoint, auth_header,
+    SendMetadataRequest(std::move(entries), endpoint, auth_header, user_agent,
                         agent_->config_.VerboseLogging());
   }
 }

src/configuration.cc

@@ -23,6 +23,14 @@
 
 #include <yaml-cpp/yaml.h>
 
+#ifndef AGENT_VERSION
+#define AGENT_VERSION 0.0
+#endif
+
+// https://gcc.gnu.org/onlinedocs/gcc-7.3.0/cpp/Stringizing.html
+#define STRINGIFY_H(x) #x
+#define STRINGIFY(x) STRINGIFY_H(x)
+
 namespace google {
 
 namespace {
@@ -35,6 +43,8 @@ constexpr const int kMetadataApiDefaultPort = 8000;
 constexpr const char kMetadataApiDefaultResourceTypeSeparator[] = ".";
 constexpr const int kMetadataReporterDefaultIntervalSeconds = 60;
 constexpr const int kMetadataReporterDefaultPurgeDeleted = false;
+constexpr const char kMetadataReporterDefaultUserAgent[] =
+    "metadata-agent/" STRINGIFY(AGENT_VERSION);
 constexpr const char kMetadataIngestionDefaultEndpointFormat[] =
     "https://stackdriver.googleapis.com/v1beta2/projects/{{project_id}}"
     "/resourceMetadata:batchUpdate";
@@ -59,7 +69,6 @@ constexpr const char kKubernetesDefaultNodeName[] = "";
 constexpr const bool kKubernetesDefaultUseWatch = true;
 constexpr const char kDefaultInstanceId[] = "";
 constexpr const char kDefaultInstanceZone[] = "";
-
 }
 
 MetadataAgentConfiguration::MetadataAgentConfiguration()
@@ -74,6 +83,8 @@ MetadataAgentConfiguration::MetadataAgentConfiguration()
           kMetadataReporterDefaultIntervalSeconds),
       metadata_reporter_purge_deleted_(
           kMetadataReporterDefaultPurgeDeleted),
+      metadata_reporter_user_agent_(
+          kMetadataReporterDefaultUserAgent),
       metadata_ingestion_endpoint_format_(
           kMetadataIngestionDefaultEndpointFormat),
       metadata_ingestion_request_size_limit_bytes_(
@@ -103,6 +114,7 @@ int MetadataAgentConfiguration::ParseArguments(int ac, char** av) {
   boost::program_options::options_description flags_desc;
   flags_desc.add_options()
       ("help,h", "Print help message")
+      ("version,V", "Print the agent version")
       ("verbose,v", boost::program_options::bool_switch(&verbose_logging_),
            "Enable verbose logging")
       ;
@@ -118,18 +130,29 @@ int MetadataAgentConfiguration::ParseArguments(int ac, char** av) {
   boost::program_options::positional_options_description positional_desc;
   positional_desc.add(kConfigFileFlag, 1);
   boost::program_options::variables_map flags;
-  boost::program_options::store(
-      boost::program_options::command_line_parser(ac, av)
-          .options(all_desc).positional(positional_desc).run(), flags);
-  boost::program_options::notify(flags);
+  try {
+    boost::program_options::store(
+        boost::program_options::command_line_parser(ac, av)
+        .options(all_desc).positional(positional_desc).run(), flags);
+    boost::program_options::notify(flags);
 
-  if (flags.count("help")) {
-    std::cout << flags_desc << std::endl;
+    if (flags.count("help")) {
+      std::cout << flags_desc << std::endl;
+      return -1;
+    }
+    if (flags.count("version")) {
+      std::cout << "Stackdriver Metadata Agent v" << STRINGIFY(AGENT_VERSION)
+                << std::endl;
+      return -1;
+    }
+
+    ParseConfigFile(config_file);
+    return 0;
+  } catch (const boost::program_options::error& arg_error) {
+    std::cerr << arg_error.what() << std::endl;
+    std::cerr << flags_desc << std::endl;
     return 1;
   }
-
-  ParseConfigFile(config_file);
-  return 0;
 }
 
 void MetadataAgentConfiguration::ParseConfigFile(const std::string& filename) {
@@ -159,6 +182,9 @@ void MetadataAgentConfiguration::ParseConfiguration(std::istream& input) {
   metadata_reporter_purge_deleted_ =
       config["MetadataReporterPurgeDeleted"].as<bool>(
           kMetadataReporterDefaultPurgeDeleted);
+  metadata_reporter_user_agent_ =
+      config["MetadataReporterUserAgent"].as<std::string>(
+          kMetadataReporterDefaultUserAgent);
   metadata_ingestion_endpoint_format_ =
       config["MetadataIngestionEndpointFormat"].as<std::string>(
           kMetadataIngestionDefaultEndpointFormat);
@@ -211,3 +237,6 @@ void MetadataAgentConfiguration::ParseConfiguration(std::istream& input) {
 }
 
 }  // google
+
+#undef STRINGIFY
+#undef STRINGIFY_H

src/configuration.h

@@ -24,6 +24,11 @@ namespace google {
 class MetadataAgentConfiguration {
  public:
   MetadataAgentConfiguration();
+  // Parse the command line.
+  // A zero return value means that parsing succeeded and the program should
+  // proceed.  A positive return value means that parsing failed.  A negative
+  // value means that parsing succeeded, but all of the arguments were handled
+  // within the function and the program should exit with a success exit code.
   int ParseArguments(int ac, char** av);
 
   // Shared configuration.
@@ -61,6 +66,10 @@ class MetadataAgentConfiguration {
     std::lock_guard<std::mutex> lock(mutex_);
     return metadata_reporter_purge_deleted_;
   }
+  const std::string& MetadataReporterUserAgent() const {
+    std::lock_guard<std::mutex> lock(mutex_);
+    return metadata_reporter_user_agent_;
+  }
   const std::string& MetadataIngestionEndpointFormat() const {
     std::lock_guard<std::mutex> lock(mutex_);
     return metadata_ingestion_endpoint_format_;
@@ -153,6 +162,7 @@ class MetadataAgentConfiguration {
   std::string metadata_api_resource_type_separator_;
   int metadata_reporter_interval_seconds_;
   bool metadata_reporter_purge_deleted_;
+  std::string metadata_reporter_user_agent_;
   std::string metadata_ingestion_endpoint_format_;
   int metadata_ingestion_request_size_limit_bytes_;
   std::string metadata_ingestion_raw_content_version_;

src/metadatad.cc

@@ -28,7 +28,7 @@ int main(int ac, char** av) {
   google::MetadataAgentConfiguration config;
   int parse_result = config.ParseArguments(ac, av);
   if (parse_result) {
-    return parse_result;
+    return parse_result < 0 ? 0 : parse_result;
   }
 
   google::MetadataAgent server(config);

test/Makefile

@@ -5,6 +5,7 @@ GTEST_SOURCEDIR=$(GTEST_DIR)/src
 GTEST_HEADERS=$(GTEST_DIR)/include/gtest/*.h \
               $(GTEST_DIR)/include/gtest/internal/*.h
 GTEST_SRCS_=$(GTEST_SOURCEDIR)/*.cc $(GTEST_SOURCEDIR)/*.h $(GTEST_HEADERS)
+GMOCK_DIR=$(LIBDIR)/googletest/googlemock
 
 # TODO: Factor out the common variables.
 CPP_NETLIB_DIR=$(LIBDIR)/cpp-netlib
@@ -13,7 +14,9 @@ YAML_CPP_LIBDIR=$(YAML_CPP_DIR)
 
 YAML_CPP_LIBS=$(YAML_CPP_LIBDIR)/libyaml-cpp.a
 
-CPPFLAGS+=-isystem $(GTEST_DIR)/include -I$(YAML_CPP_DIR)/include
+CPPFLAGS+= \
+    -isystem $(GTEST_DIR)/include -I$(GMOCK_DIR)/include \
+    -I$(YAML_CPP_DIR)/include
 CXXFLAGS=-std=c++11 -g -pthread
 LDLIBS=-lpthread -lboost_program_options -lyaml-cpp
 LDFLAGS=-L$(YAML_CPP_LIBDIR)

test/configuration_unittest.cc

@@ -1,5 +1,6 @@
 #include "../src/configuration.h"
 #include "gtest/gtest.h"
+#include "gmock/gmock.h"
 
 namespace google {
 
@@ -18,6 +19,8 @@ class MetadataAgentConfigurationTest : public ::testing::Test {
     EXPECT_EQ(".", config.MetadataApiResourceTypeSeparator());
     EXPECT_EQ(60, config.MetadataReporterIntervalSeconds());
     EXPECT_EQ(false, config.MetadataReporterPurgeDeleted());
+    EXPECT_THAT(config.MetadataReporterUserAgent(),
+                ::testing::StartsWith("metadata-agent/"));
     EXPECT_EQ("https://stackdriver.googleapis.com/"
               "v1beta2/projects/{{project_id}}/resourceMetadata:batchUpdate",
               config.MetadataIngestionEndpointFormat());
@@ -58,18 +61,20 @@ TEST_F(MetadataAgentConfigurationTest, PopulatedConfig) {
   ParseConfiguration(
       "ProjectId: TestProjectId\n"
       "MetadataApiNumThreads: 13\n"
-      "MetadataReporterPurgeDeleted: true"
+      "MetadataReporterPurgeDeleted: true\n"
+      "MetadataReporterUserAgent: \"foobar/foobaz\"\n"
   );
   EXPECT_EQ("TestProjectId", config.ProjectId());
   EXPECT_EQ(13, config.MetadataApiNumThreads());
   EXPECT_EQ(true, config.MetadataReporterPurgeDeleted());
+  EXPECT_EQ("foobar/foobaz", config.MetadataReporterUserAgent());
 }
 
 TEST_F(MetadataAgentConfigurationTest, CommentSkipped) {
   ParseConfiguration(
       "ProjectId: TestProjectId\n"
       "#MetadataApiNumThreads: 13\n"
-      "MetadataReporterPurgeDeleted: true"
+      "MetadataReporterPurgeDeleted: true\n"
   );
   EXPECT_EQ(3, config.MetadataApiNumThreads());
 }
@@ -79,7 +84,7 @@ TEST_F(MetadataAgentConfigurationTest, BlankLine) {
       "ProjectId: TestProjectId\n"
       "\n"
       "\n"
-      "MetadataReporterPurgeDeleted: true"
+      "MetadataReporterPurgeDeleted: true\n"
   );
   EXPECT_EQ("TestProjectId", config.ProjectId());
   EXPECT_EQ(true, config.MetadataReporterPurgeDeleted());