ALlow overriding hostname for node manager.

distbench_busybox.cc

@@ -57,6 +57,8 @@ ABSL_FLAG(std::string, service_address, "",
           "Incoming RPC address for the node_manager to report to the "
           "test_sequencer. Useful if DNS cannot resolve the hostname. "
           "Must include gRPC protocol host and port e.g. ipv4:///1.2.3.4:5678");
+ABSL_FLAG(std::string, service_hostname, "",
+          "Hostname for the node_manager to use. Useful for multi-homed hosts");
 
 int main(int argc, char** argv, char** envp) {
   std::vector<char*> remaining_arguments = absl::ParseCommandLine(argc, argv);
@@ -348,6 +350,7 @@ int MainTestSequencer(std::vector<char*>& arguments) {
             absl::GetFlag(FLAGS_default_data_plane_device),
         .control_plane_device = absl::GetFlag(FLAGS_control_plane_device),
         .port = &new_port,
+        .service_hostname = absl::GetFlag(FLAGS_service_hostname),
     };
     nodes.push_back(std::make_unique<distbench::NodeManager>());
     absl::Status status = nodes.back()->Initialize(opts);
@@ -413,6 +416,7 @@ int MainNodeManager(std::vector<char*>& arguments) {
       .port = &port,
       .attributes = attributes,
       .service_address = absl::GetFlag(FLAGS_service_address),
+      .service_hostname = absl::GetFlag(FLAGS_service_hostname),
   };
   distbench::NodeManager node_manager;
   absl::Status status = node_manager.Initialize(opts);

distbench_node_manager.cc

@@ -83,7 +83,7 @@ grpc::Status NodeManager::ConfigureNode(grpc::ServerContext* context,
     }
     auto& service_entry = service_map[service_name];
     service_entry.set_endpoint_address(maybe_address.value());
-    service_entry.set_hostname(Hostname());
+    service_entry.set_hostname(opts_.service_hostname);
     *service_entry.mutable_attributes() = registration_info_.attributes();
     int dimensions = std::count(service_name.begin(), service_name.end(), '/');
     Attribute* attribute;
@@ -277,6 +277,9 @@ NodeManager::~NodeManager() {
 
 absl::Status NodeManager::Initialize(const NodeManagerOpts& opts) {
   opts_ = opts;
+  if (opts_.service_hostname.empty()) {
+    opts_.service_hostname = Hostname();
+  }
   if (opts_.test_sequencer_service_address.empty()) {
     Shutdown();
     return absl::InvalidArgumentError(
@@ -312,7 +315,7 @@ absl::Status NodeManager::Initialize(const NodeManagerOpts& opts) {
   if (opts_.service_address.empty()) {
     if (!registration_info_.has_control_ip()) {
       opts_.service_address =
-          absl::StrCat("dns:///", Hostname(), ":", *opts_.port);
+          absl::StrCat("dns:///", opts_.service_hostname, ":", *opts_.port);
     } else if (listening_address[0] == '[') {
       opts_.service_address =
           absl::StrCat("ipv6:///", listening_address);
@@ -327,10 +330,10 @@ absl::Status NodeManager::Initialize(const NodeManagerOpts& opts) {
     return absl::UnknownError("NodeManager service failed to start");
   }
   LOG(INFO) << "NodeManager server listening on " << opts_.service_address
-            << " on " << Hostname();
+            << " on " << opts_.service_hostname;
 
   registration_info_.set_preassigned_node_id(opts_.preassigned_node_id);
-  registration_info_.set_hostname(Hostname());
+  registration_info_.set_hostname(opts_.service_hostname);
   registration_info_.set_control_port(*opts_.port);
   for (const auto& attr : opts_.attributes) {
     auto new_attr = registration_info_.add_attributes();

distbench_node_manager.h

@@ -34,6 +34,10 @@ struct NodeManagerOpts {
   // resolve the hostname). This is passed to gRPC unmodified, so it must be
   // a valid "target" (I.e. it must include a protocol, host and port).
   std::string service_address;
+
+  // If the hostname reported by gethostname is unresolvable this will override
+  // it for node manager registrations:
+  std::string service_hostname;
 };
 
 class NodeManager final : public DistBenchNodeManager::Service {

distbench_test_sequencer_tester.cc

@@ -67,6 +67,7 @@ absl::Status DistBenchTester::Resize(size_t num_nodes) {
     nm_opts.port = &port;
     nm_opts.test_sequencer_service_address = test_sequencer->service_address();
     nm_opts.control_plane_device = "lo";
+    nm_opts.service_hostname = "localhost";
     nodes[i] = std::make_unique<NodeManager>();
     auto ret = nodes[i]->Initialize(nm_opts);
     if (!ret.ok()) return ret;