feat(backend): Update cvd start to handle single instances

Author: SuperStrongDinosaur

base/cvd/cuttlefish/host/commands/cvd/cli/commands/BUILD.bazel

@@ -390,6 +390,7 @@ cf_cc_library(
     hdrs = ["start.h"],
     clang_format_enabled = False,
     deps = [
+        "//cuttlefish/common/libs/fs",
         "//cuttlefish/common/libs/utils:contains",
         "//cuttlefish/common/libs/utils:files",
         "//cuttlefish/common/libs/utils:json",

base/cvd/cuttlefish/host/commands/cvd/cli/commands/start.cpp

@@ -21,6 +21,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
+#include <fcntl.h>
 
 #include <algorithm>
 #include <cstdlib>
@@ -40,6 +41,7 @@
 #include "absl/strings/str_join.h"
 #include "absl/strings/str_split.h"
 
+#include "cuttlefish/common/libs/fs/shared_fd.h"
 #include "cuttlefish/common/libs/utils/contains.h"
 #include "cuttlefish/common/libs/utils/files.h"
 #include "cuttlefish/flag_parser/flag.h"
@@ -313,7 +315,8 @@ Result<std::vector<Flag>> GetCvdInternalStartFlags(
 
 CvdStartCommandHandler::CvdStartCommandHandler(
     InstanceManager& instance_manager)
-    : instance_manager_(instance_manager) {}
+    : instance_manager_(instance_manager) {
+}
 
 static Result<void> ConsumeDaemonModeFlag(cvd_common::Args& args) {
   bool daemon = true;
@@ -337,6 +340,19 @@ Result<void> CvdStartCommandHandler::Handle(const CommandRequest& request) {
     return CF_ERR(NoGroupMessage(request));
   }
 
+  if (request.Selectors().instance_names) {
+    auto [instance, group] =
+        CF_EXPECT(selector::SelectInstance(instance_manager_, request));
+
+    auto config_path =
+        group.AssemblyDir() + "/cuttlefish_config.json";
+    if (FileExists(config_path)) {
+      return LaunchSingleInstance(instance, group, request);
+    } else {
+      LOG(INFO) << "Group configuration does not exist on disk. Proceeding with normal group start.";
+    }
+  }
+
   CF_EXPECT(ConsumeDaemonModeFlag(subcmd_args));
   subcmd_args.push_back("--daemon=true");
 
@@ -477,6 +493,74 @@ Result<void> CvdStartCommandHandler::LaunchDeviceInterruptible(
   return {};
 }
 
+Result<void> CvdStartCommandHandler::LaunchSingleInstance(
+    LocalInstance& instance, LocalInstanceGroup& group,
+    const CommandRequest& request) {
+  auto bin_path = group.HostArtifactsPath() + "/bin/run_cvd";
+  cvd_common::Envs run_cvd_envs = request.Env();
+  run_cvd_envs[kCuttlefishInstanceEnvVarName] = std::to_string(instance.id());
+  run_cvd_envs["HOME"] = group.HomeDir();
+  run_cvd_envs[kAndroidHostOut] = group.HostArtifactsPath();
+  run_cvd_envs[kAndroidProductOut] = group.ProductOutPath();
+  run_cvd_envs[kAndroidSoongHostOut] = group.HostArtifactsPath();
+  run_cvd_envs[kCvdMarkEnv] = "true";
+
+  ConstructCommandParam construct_cmd_param{.bin_path = bin_path,
+                                            .home = group.HomeDir(),
+                                            .args = cvd_common::Args{},
+                                            .envs = run_cvd_envs,
+                                            .working_dir = CurrentDirectory(),
+                                            .command_name = "run_cvd"};
+
+  Command command = CF_EXPECT(ConstructCommand(construct_cmd_param));
+  command.RedirectStdIO(Subprocess::StdIOChannel::kStdOut,
+                        Subprocess::StdIOChannel::kStdErr);
+  SharedFD dev_null = SharedFD::Open("/dev/null", O_RDONLY);
+  if (dev_null->IsOpen()) {
+    command.RedirectStdIO(Subprocess::StdIOChannel::kStdIn, dev_null);
+  } else {
+    LOG(ERROR) << "Failed to open /dev/null: " << dev_null->StrError();
+  }
+
+  auto symlink_config_res = SymlinkPreviousConfig(group.HomeDir());
+  if (!symlink_config_res.ok()) {
+    LOG(ERROR) << "Failed to symlink the config file at system wide home: "
+               << symlink_config_res.error();
+  }
+
+  auto set_instance_state = [&group, &instance](cvd::InstanceState state) {
+    for (auto& inst : group.Instances()) {
+      if (inst.id() == instance.id()) {
+        inst.set_state(state);
+        break;
+      }
+    }
+  };
+
+  set_instance_state(cvd::INSTANCE_STATE_STARTING);
+  group.SetStartTime(CvdServerClock::now());
+  CF_EXPECT(instance_manager_.UpdateInstanceGroup(group));
+
+  Result<void> start_res =
+      LaunchDevice(std::move(command), group, run_cvd_envs, request);
+
+  if (!start_res.ok()) {
+    set_instance_state(cvd::INSTANCE_STATE_BOOT_FAILED);
+    CF_EXPECT(instance_manager_.UpdateInstanceGroup(group));
+    return start_res;
+  }
+
+  set_instance_state(cvd::INSTANCE_STATE_RUNNING);
+  CF_EXPECT(instance_manager_.UpdateInstanceGroup(group));
+
+  auto group_json = CF_EXPECT(group.FetchStatus());
+  std::cout << group_json.toStyledString();
+
+  return {};
+}
+
+
+
 std::vector<HelpParagraph> CvdStartCommandHandler::Description() const {
   std::vector<HelpParagraph> description;
   description.emplace_back(

base/cvd/cuttlefish/host/commands/cvd/cli/commands/start.h

@@ -43,6 +43,10 @@ class CvdStartCommandHandler : public CvdCommandHandler {
   bool RequiresDeviceExists() const override { return true; }
 
  private:
+  Result<void> LaunchSingleInstance(LocalInstance& instance,
+                                    LocalInstanceGroup& group,
+                                    const CommandRequest& request);
+
   Result<void> LaunchDevice(Command command, LocalInstanceGroup& group,
                             const cvd_common::Envs& envs,
                             const CommandRequest& request);