add `--write-config` to zenserver options (#382)

- Feature: `zen up` command has two new command line options
  - `--config <file_path>` tells zenserver to start with a specific config file
  - `--owner-pid <pid>` tells zenserver to start with a owning process id
- Feature: `zen attach` command to add additional owning processes to a running zenserver instance
  - `--owner-pid <pid>` adds pid to running zenserver instance list of owning processes
- Feature: `--write-config` command line option for zenserver
  - `--write-config <file_path>` path to a file which will contain a lua config file for zenserver combining all command line options and optional lua config files
- Improvement: `zen up` command will check if zenserver is currently running before starting up a new instance

4 files changed, 115 insertions, 11 deletions

diff --git a/src/zen/cmds/up.cpp b/src/zen/cmds/up.cpp
index 69bcbe829..d1ae0794a 100644
--- a/src/zen/cmds/up.cpp
+++ b/src/zen/cmds/up.cpp
@@ -12,6 +12,13 @@ namespace zen {
 
 UpCommand::UpCommand()
 {
+	m_Options.add_option("lifetime",
+						 "",
+						 "owner-pid",
+						 "Specify owning process id",
+						 cxxopts::value(m_OwnerPid)->default_value("0"),
+						 "<identifier>");
+	m_Options.add_options()("config", "Path to Lua config file", cxxopts::value(m_ConfigFile));
 }
 
 UpCommand::~UpCommand() = default;
@@ -21,12 +28,34 @@ UpCommand::Run(const ZenCliOptions& GlobalOptions, int argc, char** argv)
 {
 	ZEN_UNUSED(GlobalOptions, argc, argv);
 
-	std::filesystem::path ExePath = zen::GetRunningExecutablePath();
+	if (!ParseOptions(argc, argv))
+	{
+		return 0;
+	}
 
-	ZenServerEnvironment ServerEnvironment;
+	{
+		ZenServerState State;
+		if (State.InitializeReadOnly())
+		{
+			ZEN_CONSOLE("Zen server already running");
+			return 0;
+		}
+	}
+
+	std::filesystem::path ExePath = zen::GetRunningExecutablePath();
+	ZenServerEnvironment  ServerEnvironment;
 	ServerEnvironment.Initialize(ExePath.parent_path());
 	ZenServerInstance Server(ServerEnvironment);
-	Server.SpawnServer();
+	if (m_OwnerPid != 0)
+	{
+		Server.SetOwnerPid(m_OwnerPid);
+	}
+	std::string AdditionalArguments;
+	if (!m_ConfigFile.empty())
+	{
+		AdditionalArguments = fmt::format("--config {}", m_ConfigFile);
+	}
+	Server.SpawnServer(0, AdditionalArguments);
 
 	int Timeout = 10000;
 
@@ -44,6 +73,45 @@ UpCommand::Run(const ZenCliOptions& GlobalOptions, int argc, char** argv)
 
 //////////////////////////////////////////////////////////////////////////
 
+AttachCommand::AttachCommand()
+{
+	m_Options.add_option("", "p", "port", "Host port", cxxopts::value(m_Port)->default_value("1337"), "<hostport>");
+	m_Options.add_option("lifetime", "", "owner-pid", "Specify owning process id", cxxopts::value(m_OwnerPid), "<identifier>");
+}
+
+AttachCommand::~AttachCommand() = default;
+
+int
+AttachCommand::Run(const ZenCliOptions& GlobalOptions, int argc, char** argv)
+{
+	ZEN_UNUSED(GlobalOptions, argc, argv);
+
+	if (!ParseOptions(argc, argv))
+	{
+		return 0;
+	}
+
+	ZenServerState Instance;
+	Instance.Initialize();
+	ZenServerState::ZenServerEntry* Entry = Instance.Lookup(m_Port);
+	if (!Entry)
+	{
+		ZEN_WARN("no zen server instance to add sponsor process to");
+		return 1;
+	}
+
+	if (!Entry->AddSponsorProcess(m_OwnerPid))
+	{
+		ZEN_WARN("unable to add sponsor process to running zen server instance");
+		return 1;
+	}
+
+	ZEN_CONSOLE("added sponsor process {} to running instance {} on port {}", m_OwnerPid, Entry->Pid.load(), m_Port);
+	return 0;
+}
+
+//////////////////////////////////////////////////////////////////////////
+
 DownCommand::DownCommand()
 {
 	m_Options.add_option("", "p", "port", "Host port", cxxopts::value(m_Port)->default_value("1337"), "<hostport>");
@@ -97,7 +165,7 @@ DownCommand::Run(const ZenCliOptions& GlobalOptions, int argc, char** argv)
 
 	// Since we cannot obtain a handle to the process we are unable to block on the process
 	// handle to determine when the server has shut down. Thus we signal that we would like
-	// a shutdown via the shutdown flag and then
+	// a shutdown via the shutdown flag and then exit.
 
 	ZEN_CONSOLE("requesting shutdown of server on port {}", m_Port);
 	Entry->SignalShutdownRequest();
diff --git a/src/zen/cmds/up.h b/src/zen/cmds/up.h
index 5af05541a..5b5c6a3f8 100644
--- a/src/zen/cmds/up.h
+++ b/src/zen/cmds/up.h
@@ -17,6 +17,24 @@ public:
 
 private:
 	cxxopts::Options m_Options{"up", "Bring up zen service"};
+	uint16_t		 m_Port;
+	int				 m_OwnerPid;
+	std::string		 m_ConfigFile;
+};
+
+class AttachCommand : public ZenCmdBase
+{
+public:
+	AttachCommand();
+	~AttachCommand();
+
+	virtual int				  Run(const ZenCliOptions& GlobalOptions, int argc, char** argv) override;
+	virtual cxxopts::Options& Options() override { return m_Options; }
+
+private:
+	cxxopts::Options m_Options{"attach", "Add a sponsor process to a running zen service"};
+	uint16_t		 m_Port;
+	int				 m_OwnerPid;
 };
 
 class DownCommand : public ZenCmdBase
diff --git a/src/zen/zen.cpp b/src/zen/zen.cpp
index 204a91f74..f1cfe9796 100644
--- a/src/zen/zen.cpp
+++ b/src/zen/zen.cpp
@@ -216,6 +216,7 @@ main(int argc, char** argv)
 	StatusCommand			 StatusCmd;
 	TopCommand				 TopCmd;
 	UpCommand				 UpCmd;
+	AttachCommand			 AttachCmd;
 	VersionCommand			 VersionCmd;
 #if ZEN_WITH_TESTS
 	RunTestsCommand RunTestsCmd;
@@ -263,6 +264,7 @@ main(int argc, char** argv)
 		{"status",				&StatusCmd,				"Show zen status"},
 		{"top",					&TopCmd,				"Monitor zen server activity"},
 		{"up",					&UpCmd,					"Bring zen server up"},
+		{"attach",				&AttachCmd,				"Add a sponsor process to a running zen service"},
 		{"version",				&VersionCmd,			"Get zen server version"},
 #if ZEN_WITH_TESTS
 		{"runtests",			&RunTestsCmd,			"Run zen tests"},
diff --git a/src/zenserver/config.cpp b/src/zenserver/config.cpp
index 2d286b02a..1f5a3eb21 100644
--- a/src/zenserver/config.cpp
+++ b/src/zenserver/config.cpp
@@ -10,6 +10,7 @@
 #include <zencore/iobuffer.h>
 #include <zencore/string.h>
 #include <zenhttp/zenhttp.h>
+#include <zenutil/basicfile.h>
 
 ZEN_THIRD_PARTY_INCLUDES_START
 #include <fmt/format.h>
@@ -136,15 +137,15 @@ ParseBucketConfigs(std::span<std::string> Buckets)
 }
 
 static std::string
-MakeSafePath(const std::string& Path)
+MakeSafePath(const std::string_view Path)
 {
 #if ZEN_PLATFORM_WINDOWS
 	if (Path.empty())
 	{
-		return Path;
+		return std::string(Path);
 	}
 
-	std::string FixedPath = Path;
+	std::string FixedPath(Path);
 	std::replace(FixedPath.begin(), FixedPath.end(), '/', '\\');
 	if (!FixedPath.starts_with("\\\\?\\"))
 	{
@@ -152,7 +153,7 @@ MakeSafePath(const std::string& Path)
 	}
 	return FixedPath;
 #else
-	return Path;
+	return std::string(Path);
 #endif
 };
 
@@ -768,7 +769,10 @@ private:
 }  // namespace LuaConfig
 
 void
-ParseConfigFile(const std::filesystem::path& Path, ZenServerOptions& ServerOptions, const cxxopts::ParseResult& CmdLineResult)
+ParseConfigFile(const std::filesystem::path& Path,
+				ZenServerOptions&			 ServerOptions,
+				const cxxopts::ParseResult&	 CmdLineResult,
+				std::string_view			 OutputConfigFile)
 {
 	using namespace std::literals;
 
@@ -923,6 +927,16 @@ ParseConfigFile(const std::filesystem::path& Path, ZenServerOptions& ServerOptio
 	{
 		LuaOptions.Touch("server.objectstore.buckets"sv);
 	}
+
+	if (!OutputConfigFile.empty())
+	{
+		std::filesystem::path			  WritePath(MakeSafePath(OutputConfigFile));
+		zen::ExtendableStringBuilder<512> ConfigStringBuilder;
+		LuaOptions.Print(ConfigStringBuilder, CmdLineResult);
+		zen::BasicFile Output;
+		Output.Open(WritePath, zen::BasicFile::Mode::kTruncate);
+		Output.Write(ConfigStringBuilder.Data(), ConfigStringBuilder.Size(), 0);
+	}
 }
 
 void
@@ -943,6 +957,7 @@ ParseCliOptions(int argc, char* argv[], ZenServerOptions& ServerOptions)
 	std::string ContentDir;
 	std::string AbsLogFile;
 	std::string ConfigFile;
+	std::string OutputConfigFile;
 
 	cxxopts::Options options("zenserver", "Zen Server");
 	options.add_options()("dedicated",
@@ -956,6 +971,7 @@ ParseCliOptions(int argc, char* argv[], ZenServerOptions& ServerOptions)
 	options.add_options()("content-dir", "Frontend content directory", cxxopts::value<std::string>(ContentDir));
 	options.add_options()("abslog", "Path to log file", cxxopts::value<std::string>(AbsLogFile));
 	options.add_options()("config", "Path to Lua config file", cxxopts::value<std::string>(ConfigFile));
+	options.add_options()("write-config", "Path to output Lua config file", cxxopts::value<std::string>(OutputConfigFile));
 	options.add_options()("no-sentry",
 						  "Disable Sentry crash handler",
 						  cxxopts::value<bool>(ServerOptions.NoSentry)->default_value("false"));
@@ -1380,11 +1396,11 @@ ParseCliOptions(int argc, char* argv[], ZenServerOptions& ServerOptions)
 
 		if (!ServerOptions.ConfigFile.empty())
 		{
-			ParseConfigFile(ServerOptions.ConfigFile, ServerOptions, result);
+			ParseConfigFile(ServerOptions.ConfigFile, ServerOptions, result, OutputConfigFile);
 		}
 		else
 		{
-			ParseConfigFile(ServerOptions.DataDir / "zen_cfg.lua", ServerOptions, result);
+			ParseConfigFile(ServerOptions.DataDir / "zen_cfg.lua", ServerOptions, result, OutputConfigFile);
 		}
 
 		ValidateOptions(ServerOptions);