feat(connect): add --connect flag to connect to remote cluster machine without using config

cmd/uncloud/machine/init.go

@@ -77,7 +77,7 @@ func NewInitCommand() *cobra.Command {
 	)
 	cmd.Flags().StringVarP(
 		&opts.sshKey, "ssh-key", "i", "",
-		"path to SSH private key for SSH remote login. (default ~/.ssh/id_*)",
+		"Path to SSH private key for SSH remote login. (default ~/.ssh/id_*)",
 	)
 	cmd.Flags().StringVarP(
 		&opts.cluster, "cluster", "c", "",

cmd/uncloud/main.go

@@ -4,32 +4,53 @@ import (
 	"context"
 	"fmt"
 	"github.com/spf13/cobra"
-	"os"
+	"net/netip"
 	"strings"
 	"uncloud/cmd/uncloud/caddy"
 	"uncloud/cmd/uncloud/dns"
 	"uncloud/cmd/uncloud/machine"
 	"uncloud/cmd/uncloud/service"
 	"uncloud/internal/cli"
+	"uncloud/internal/cli/config"
+	"uncloud/internal/fs"
 )
 
+type globalOptions struct {
+	configPath string
+	connect    string
+}
+
 func main() {
-	var configPath string
+	opts := globalOptions{}
 	cmd := &cobra.Command{
 		Use:           "uncloud",
 		Short:         "A CLI tool for managing Uncloud resources such as clusters, machines, and services.",
 		SilenceUsage:  true,
 		SilenceErrors: true,
 		PersistentPreRunE: func(cmd *cobra.Command, args []string) error {
-			if strings.HasPrefix(configPath, "~/") {
-				home, err := os.UserHomeDir()
-				if err != nil {
-					return fmt.Errorf("get user home directory to resolve %q: %w", configPath, err)
+			var conn *config.MachineConnection
+			if opts.connect != "" {
+				if strings.HasPrefix(opts.connect, "tcp://") {
+					addrPort, err := netip.ParseAddrPort(opts.connect[len("tcp://"):])
+					if err != nil {
+						return fmt.Errorf("parse TCP address: %w", err)
+					}
+					conn = &config.MachineConnection{
+						TCP: addrPort,
+					}
+				} else {
+					dest := opts.connect
+					if strings.HasPrefix(dest, "ssh://") {
+						dest = dest[len("ssh://"):]
+					}
+					conn = &config.MachineConnection{
+						SSH: config.SSHDestination(dest),
+					}
 				}
-				configPath = strings.Replace(configPath, "~", home, 1)
 			}
 
-			uncli, err := cli.New(configPath)
+			configPath := fs.ExpandHomeDir(opts.configPath)
+			uncli, err := cli.New(configPath, conn)
 			if err != nil {
 				return fmt.Errorf("initialize CLI: %w", err)
 			}
@@ -37,9 +58,13 @@ func main() {
 			return nil
 		},
 	}
+
+	cmd.PersistentFlags().StringVar(&opts.connect, "connect", "",
+		"Connect to a remote cluster machine without using the Uncloud configuration file.\n"+
+			"Format: [ssh://]user@host[:port] or tcp://host:port")
 	// TODO: allow to override using UNCLOUD_CONFIG env var.
-	cmd.PersistentFlags().StringVar(&configPath, "uncloud-config", "~/.config/uncloud/config.toml",
-		"path to the Uncloud configuration file.")
+	cmd.PersistentFlags().StringVar(&opts.configPath, "uncloud-config", "~/.config/uncloud/config.toml",
+		"Path to the Uncloud configuration file.")
 	_ = cmd.MarkPersistentFlagFilename("uncloud-config", "toml")
 
 	cmd.AddCommand(