Allow configuring the host address binding for the local resource API.

src/agent.cc

@@ -30,8 +30,8 @@ MetadataAgent::~MetadataAgent() {}
 
 void MetadataAgent::Start() {
   metadata_api_server_.reset(new MetadataApiServer(
-      config_, &health_checker_, store_, config_.MetadataApiNumThreads(), "0.0.0.0",
-      config_.MetadataApiPort()));
+      config_, &health_checker_, store_, config_.MetadataApiNumThreads(),
+      config_.MetadataApiHostAddress(), config_.MetadataApiPort()));
   reporter_.reset(new MetadataReporter(
       config_, &store_, config_.MetadataReporterIntervalSeconds()));
 }

src/configuration.cc

@@ -41,6 +41,7 @@ constexpr const char kDefaultProjectId[] = "";
 constexpr const char kDefaultCredentialsFile[] = "";
 constexpr const int kMetadataApiDefaultNumThreads = 3;
 constexpr const int kMetadataApiDefaultPort = 8000;
+constexpr const char kMetadataApiDefaultHostAddress[] = "0.0.0.0";
 constexpr const char kMetadataApiDefaultResourceTypeSeparator[] = ".";
 constexpr const int kMetadataReporterDefaultIntervalSeconds = 60;
 constexpr const int kMetadataReporterDefaultPurgeDeleted = false;
@@ -85,6 +86,7 @@ Configuration::Configuration()
       verbose_logging_(false),
       metadata_api_num_threads_(kMetadataApiDefaultNumThreads),
       metadata_api_port_(kMetadataApiDefaultPort),
+      metadata_api_host_address_(kMetadataApiDefaultHostAddress),
       metadata_api_resource_type_separator_(
           kMetadataApiDefaultResourceTypeSeparator),
       metadata_reporter_interval_seconds_(
@@ -222,6 +224,9 @@ void Configuration::ParseConfiguration(std::istream& input) {
       config["MetadataApiNumThreads"].as<int>(metadata_api_num_threads_);
   metadata_api_port_ =
       config["MetadataApiPort"].as<int>(metadata_api_port_);
+  metadata_api_host_address_ =
+      config["MetadataApiHostAddress"].as<std::string>(
+          metadata_api_host_address_);
   metadata_api_resource_type_separator_ =
       config["MetadataApiResourceTypeSeparator"].as<std::string>(
           metadata_api_resource_type_separator_);

src/configuration.h

@@ -52,6 +52,10 @@ class Configuration {
     std::lock_guard<std::mutex> lock(mutex_);
     return metadata_api_port_;
   }
+  const std::string& MetadataApiHostAddress() const {
+    std::lock_guard<std::mutex> lock(mutex_);
+    return metadata_api_host_address_;
+  }
   const std::string& MetadataApiResourceTypeSeparator() const {
     std::lock_guard<std::mutex> lock(mutex_);
     return metadata_api_resource_type_separator_;
@@ -186,6 +190,7 @@ class Configuration {
   bool verbose_logging_;
   int metadata_api_num_threads_;
   int metadata_api_port_;
+  std::string metadata_api_host_address_;
   std::string metadata_api_resource_type_separator_;
   int metadata_reporter_interval_seconds_;
   bool metadata_reporter_purge_deleted_;

test/configuration_unittest.cc

@@ -9,6 +9,7 @@ void VerifyDefaultConfig(const Configuration& config) {
   EXPECT_EQ("", config.CredentialsFile());
   EXPECT_EQ(3, config.MetadataApiNumThreads());
   EXPECT_EQ(8000, config.MetadataApiPort());
+  EXPECT_EQ("0.0.0.0", config.MetadataApiHostAddress());
   EXPECT_EQ(".", config.MetadataApiResourceTypeSeparator());
   EXPECT_EQ(60, config.MetadataReporterIntervalSeconds());
   EXPECT_EQ(false, config.MetadataReporterPurgeDeleted());