feat: make connection method using system 'ssh' the default (add ssh+go:// fallback)

internal/cli/cli.go

@@ -263,8 +263,8 @@ func (cli *CLI) initRemoteMachine(ctx context.Context, opts InitClusterOptions)
 		SSHKeyFile: opts.RemoteMachine.KeyPath,
 		MachineID:  resp.Machine.Id,
 	}
-	if opts.RemoteMachine.UseSSHCLI {
-		connCfg.SSHCLI = config.NewSSHDestination(
+	if opts.RemoteMachine.UseSSHGo {
+		connCfg.SSHGo = config.NewSSHDestination(
 			opts.RemoteMachine.User,
 			opts.RemoteMachine.Host,
 			opts.RemoteMachine.Port,
@@ -467,8 +467,8 @@ func (cli *CLI) AddMachine(ctx context.Context, opts AddMachineOptions) (*client
 		SSHKeyFile: opts.RemoteMachine.KeyPath,
 		MachineID:  addResp.Machine.Id,
 	}
-	if opts.RemoteMachine.UseSSHCLI {
-		connCfg.SSHCLI = config.NewSSHDestination(
+	if opts.RemoteMachine.UseSSHGo {
+		connCfg.SSHGo = config.NewSSHDestination(
 			opts.RemoteMachine.User,
 			opts.RemoteMachine.Host,
 			opts.RemoteMachine.Port,
@@ -498,73 +498,75 @@ func (cli *CLI) AddMachine(ctx context.Context, opts AddMachineOptions) (*client
 func provisionOrConnectRemoteMachine(
 	ctx context.Context, remoteMachine *RemoteMachine, skipInstall bool, version string,
 ) (*client.Client, error) {
-	// Use SSH CLI
-	if remoteMachine.UseSSHCLI {
-		exec := sshexec.NewSSHCLIRemote(
-			remoteMachine.User,
-			remoteMachine.Host,
-			remoteMachine.Port,
-			remoteMachine.KeyPath,
+	// Use Go's built-in SSH library.
+	if remoteMachine.UseSSHGo {
+		sshClient, err := sshexec.Connect(
+			remoteMachine.User, remoteMachine.Host, remoteMachine.Port, remoteMachine.KeyPath,
 		)
+		// If the SSH connection using SSH agent fails and no key path is provided, try to use the default SSH key.
+		if err != nil && remoteMachine.KeyPath == "" {
+			remoteMachine.KeyPath = DefaultSSHKeyPath
+			sshClient, err = sshexec.Connect(
+				remoteMachine.User, remoteMachine.Host, remoteMachine.Port, remoteMachine.KeyPath,
+			)
+		}
+		if err != nil {
+			return nil, fmt.Errorf(
+				"SSH login to remote machine %s: %w",
+				config.NewSSHDestination(remoteMachine.User, remoteMachine.Host, remoteMachine.Port), err,
+			)
+		}
 
 		if !skipInstall {
-			if err := provisionMachine(ctx, exec, version); err != nil {
+			// Provision the remote machine by installing the Uncloud daemon and dependencies over SSH.
+			exec := sshexec.NewRemote(sshClient)
+			if err = provisionMachine(ctx, exec, version); err != nil {
 				return nil, fmt.Errorf("provision machine: %w", err)
 			}
 		}
 
-		sshConfig := &connector.SSHConnectorConfig{
-			User:    remoteMachine.User,
-			Host:    remoteMachine.Host,
-			Port:    remoteMachine.Port,
-			KeyPath: remoteMachine.KeyPath,
+		var machineClient *client.Client
+		if remoteMachine.User == "root" || skipInstall {
+			// Create a machine API client over the established SSH connection to the remote machine.
+			machineClient, err = client.New(ctx, connector.NewSSHConnectorFromClient(sshClient))
+		} else {
+			// Since the user is not root, we need to establish a new SSH connection to make the user's addition
+			// to the uncloud group effective, thus allowing access to the Uncloud daemon Unix socket.
+			sshConfig := &connector.SSHConnectorConfig{
+				User:    remoteMachine.User,
+				Host:    remoteMachine.Host,
+				Port:    remoteMachine.Port,
+				KeyPath: remoteMachine.KeyPath,
+			}
+			machineClient, err = client.New(ctx, connector.NewSSHConnector(sshConfig))
 		}
-		machineClient, err := client.New(ctx, connector.NewSSHCLIConnector(sshConfig))
 		if err != nil {
 			return nil, fmt.Errorf("connect to remote machine: %w", err)
 		}
 		return machineClient, nil
 	}
 
-	// Use Go SSH
-	sshClient, err := sshexec.Connect(remoteMachine.User, remoteMachine.Host, remoteMachine.Port, remoteMachine.KeyPath)
-	// If the SSH connection using SSH agent fails and no key path is provided, try to use the default SSH key.
-	if err != nil && remoteMachine.KeyPath == "" {
-		remoteMachine.KeyPath = DefaultSSHKeyPath
-		sshClient, err = sshexec.Connect(
-			remoteMachine.User, remoteMachine.Host, remoteMachine.Port, remoteMachine.KeyPath,
-		)
-	}
-	if err != nil {
-		return nil, fmt.Errorf(
-			"SSH login to remote machine %s: %w",
-			config.NewSSHDestination(remoteMachine.User, remoteMachine.Host, remoteMachine.Port), err,
-		)
-	}
+	// Use the system 'ssh' command (default).
+	exec := sshexec.NewSSHCLIRemote(
+		remoteMachine.User,
+		remoteMachine.Host,
+		remoteMachine.Port,
+		remoteMachine.KeyPath,
+	)
 
 	if !skipInstall {
-		// Provision the remote machine by installing the Uncloud daemon and dependencies over SSH.
-		exec := sshexec.NewRemote(sshClient)
-		if err = provisionMachine(ctx, exec, version); err != nil {
+		if err := provisionMachine(ctx, exec, version); err != nil {
 			return nil, fmt.Errorf("provision machine: %w", err)
 		}
 	}
 
-	var machineClient *client.Client
-	if remoteMachine.User == "root" || skipInstall {
-		// Create a machine API client over the established SSH connection to the remote machine.
-		machineClient, err = client.New(ctx, connector.NewSSHConnectorFromClient(sshClient))
-	} else {
-		// Since the user is not root, we need to establish a new SSH connection to make the user's addition
-		// to the uncloud group effective, thus allowing access to the Uncloud daemon Unix socket.
-		sshConfig := &connector.SSHConnectorConfig{
-			User:    remoteMachine.User,
-			Host:    remoteMachine.Host,
-			Port:    remoteMachine.Port,
-			KeyPath: remoteMachine.KeyPath,
-		}
-		machineClient, err = client.New(ctx, connector.NewSSHConnector(sshConfig))
+	sshConfig := &connector.SSHConnectorConfig{
+		User:    remoteMachine.User,
+		Host:    remoteMachine.Host,
+		Port:    remoteMachine.Port,
+		KeyPath: remoteMachine.KeyPath,
 	}
+	machineClient, err := client.New(ctx, connector.NewSSHCLIConnector(sshConfig))
 	if err != nil {
 		return nil, fmt.Errorf("connect to remote machine: %w", err)
 	}

internal/cli/config/connection.go

@@ -12,8 +12,12 @@ import (
 )
 
 type MachineConnection struct {
-	SSH        SSHDestination `yaml:"ssh,omitempty"`
-	SSHCLI     SSHDestination `yaml:"ssh_cli,omitempty"`
+	// SSH uses the system ssh CLI command to connect. This is the default SSH connection method.
+	SSH SSHDestination `yaml:"ssh,omitempty"`
+	// SSHCLI is a backward-compatible alias for SSH.
+	SSHCLI SSHDestination `yaml:"ssh_cli,omitempty"`
+	// SSHGo uses Go's built-in SSH library to connect.
+	SSHGo      SSHDestination `yaml:"ssh_go,omitempty"`
 	SSHKeyFile string         `yaml:"ssh_key_file,omitempty"`
 	// TCP is the address and port of the machine's API server.
 	// The pointer is used to omit the field when not set. Otherwise, yaml marshalling includes an empty object.
@@ -29,7 +33,9 @@ func (c *MachineConnection) String() string {
 	if c.SSH != "" {
 		return "ssh://" + string(c.SSH)
 	} else if c.SSHCLI != "" {
-		return "ssh+cli://" + string(c.SSHCLI)
+		return "ssh://" + string(c.SSHCLI)
+	} else if c.SSHGo != "" {
+		return "ssh+go://" + string(c.SSHGo)
 	} else if c.TCP != nil && c.TCP.IsValid() {
 		return fmt.Sprintf("tcp://%s", c.TCP)
 	} else if c.Unix != "" {
@@ -46,6 +52,9 @@ func (c *MachineConnection) Validate() error {
 	if c.SSHCLI != "" {
 		setCount++
 	}
+	if c.SSHGo != "" {
+		setCount++
+	}
 	if c.TCP != nil && c.TCP.IsValid() {
 		setCount++
 	}
@@ -54,10 +63,10 @@ func (c *MachineConnection) Validate() error {
 	}
 
 	if setCount == 0 {
-		return errors.New("no connection method specified (ssh, ssh_cli, tcp, or unix required)")
+		return errors.New("no connection method specified (ssh, ssh_go, tcp, or unix required)")
 	}
 	if setCount > 1 {
-		return errors.New("only one connection method allowed per connection (ssh, ssh_cli, tcp, or unix)")
+		return errors.New("only one connection method allowed per connection (ssh, ssh_go, tcp, or unix)")
 	}
 
 	return nil

internal/cli/config/connection_test.go

@@ -30,18 +30,32 @@ func TestMachineConnection_String(t *testing.T) {
 			want: "ssh://user@host.com:2222",
 		},
 		{
-			name: "ssh_cli connection",
+			name: "ssh_cli connection (backward compat alias for ssh)",
 			conn: MachineConnection{
 				SSHCLI: "user@host.com",
 			},
-			want: "ssh+cli://user@host.com",
+			want: "ssh://user@host.com",
 		},
 		{
-			name: "ssh_cli connection with port",
+			name: "ssh_cli connection with port (backward compat alias for ssh)",
 			conn: MachineConnection{
 				SSHCLI: "user@host.com:2222",
 			},
-			want: "ssh+cli://user@host.com:2222",
+			want: "ssh://user@host.com:2222",
+		},
+		{
+			name: "ssh_go connection",
+			conn: MachineConnection{
+				SSHGo: "user@host.com",
+			},
+			want: "ssh+go://user@host.com",
+		},
+		{
+			name: "ssh_go connection with port",
+			conn: MachineConnection{
+				SSHGo: "user@host.com:2222",
+			},
+			want: "ssh+go://user@host.com:2222",
 		},
 		{
 			name: "tcp connection",
@@ -103,12 +117,19 @@ func TestMachineConnection_Validate(t *testing.T) {
 			wantErr: false,
 		},
 		{
-			name: "ssh_cli only - valid",
+			name: "ssh_cli only - valid (backward compat)",
 			conn: MachineConnection{
 				SSHCLI: "user@host",
 			},
 			wantErr: false,
 		},
+		{
+			name: "ssh_go only - valid",
+			conn: MachineConnection{
+				SSHGo: "user@host",
+			},
+			wantErr: false,
+		},
 		{
 			name: "tcp only - valid",
 			conn: MachineConnection{
@@ -141,6 +162,15 @@ func TestMachineConnection_Validate(t *testing.T) {
 			wantErr: true,
 			errMsg:  "only one connection method allowed",
 		},
+		{
+			name: "ssh and ssh_go - error",
+			conn: MachineConnection{
+				SSH:   "user@host",
+				SSHGo: "user@host",
+			},
+			wantErr: true,
+			errMsg:  "only one connection method allowed",
+		},
 		{
 			name: "ssh and unix - error",
 			conn: MachineConnection{

internal/cli/connect.go

@@ -57,9 +57,9 @@ func connectClusterWithProgress(ctx context.Context, conn config.MachineConnecti
 }
 
 func connectCluster(ctx context.Context, conn config.MachineConnection) (*client.Client, error) {
-	// Determine which SSH type is configured
+	// Determine which SSH type is configured.
 	var sshDest config.SSHDestination
-	var useSSHCLI bool
+	var useGoSSH bool
 
 	// Validate connection configuration early to provide clear error messages.
 	if err := conn.Validate(); err != nil {
@@ -67,11 +67,15 @@ func connectCluster(ctx context.Context, conn config.MachineConnection) (*client
 	}
 
 	if conn.SSH != "" {
+		// SSH uses the system ssh CLI command (default).
 		sshDest = conn.SSH
-		useSSHCLI = false
 	} else if conn.SSHCLI != "" {
+		// SSHCLI is a backward-compatible alias for SSH.
 		sshDest = conn.SSHCLI
-		useSSHCLI = true
+	} else if conn.SSHGo != "" {
+		// SSHGo uses Go's built-in SSH library.
+		sshDest = conn.SSHGo
+		useGoSSH = true
 	} else if conn.TCP != nil && conn.TCP.IsValid() {
 		return client.New(ctx, connector.NewTCPConnector(*conn.TCP))
 	} else if conn.Unix != "" {
@@ -95,11 +99,11 @@ func connectCluster(ctx context.Context, conn config.MachineConnection) (*client
 		KeyPath: keyPath,
 	}
 
-	// Create appropriate connector based on type
-	if useSSHCLI {
-		return client.New(ctx, connector.NewSSHCLIConnector(sshConfig))
+	// Create appropriate connector based on type.
+	if useGoSSH {
+		return client.New(ctx, connector.NewSSHConnector(sshConfig))
 	}
-	return client.New(ctx, connector.NewSSHConnector(sshConfig))
+	return client.New(ctx, connector.NewSSHCLIConnector(sshConfig))
 }
 
 // connectModel is a TUI model for connecting to a cluster with a progress spinner.

internal/cli/machine.go

@@ -23,11 +23,11 @@ const (
 )
 
 type RemoteMachine struct {
-	User      string
-	Host      string
-	Port      int
-	KeyPath   string
-	UseSSHCLI bool // indicates ssh+cli:// should be used
+	User     string
+	Host     string
+	Port     int
+	KeyPath  string
+	UseSSHGo bool // Use Go's built-in SSH library instead of the system ssh CLI command.
 }
 
 func installCmd(user string, version string) string {