rdctl: add rdctl info --field=ip-address

This returns the IP address of the VM; which interface is returned depends
on the platform and configuration.

Signed-off-by: Mark Yen <[email protected]>

Author: mook-as

src/go/rdctl/cmd/info.go

@@ -38,17 +38,37 @@ var infoSettings struct {
 var infoCmd = &cobra.Command{
 	Use:   "info",
 	Short: "Return information about Rancher Desktop",
-	Long: `Returns information about Rancher Desktop.  The command returns all
-fields in JSON by default, but a single field can be selected.
-`,
-	RunE: doInfoCommand,
+	Long:  makeLongHelp(),
+	RunE:  doInfoCommand,
 }
 
 func init() {
 	rootCmd.AddCommand(infoCmd)
 	infoCmd.Flags().StringVarP(&infoSettings.Field, "field", "f", "", "return only a specific field")
 }
 
+// Generates help text for each field available.
+func makeLongHelp() string {
+	var builder strings.Builder
+
+	_, _ = builder.WriteString("Returns information about Rancher Desktop.  The command returns all\n")
+	_, _ = builder.WriteString("fields in JSON by default, but a single field can be selected.\n")
+	_, _ = builder.WriteString("\n")
+	_, _ = builder.WriteString("The available fields are:\n")
+
+	typ := reflect.TypeFor[info.Info]()
+	for i := range typ.NumField() {
+		field := typ.Field(i)
+		helpText := field.Tag.Get("help")
+		if helpText == "" {
+			continue
+		}
+		fieldName := strings.SplitN(field.Tag.Get("json"), ",", 2)[0]
+		_, _ = fmt.Fprintf(&builder, "  %-10s    %s\n", fieldName, helpText)
+	}
+	return builder.String()
+}
+
 func doInfoCommand(cmd *cobra.Command, args []string) error {
 	var result info.Info
 	var rdClient client.RDClient

src/go/rdctl/pkg/info/ipaddress.go

@@ -0,0 +1,72 @@
+package info
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"fmt"
+	"os"
+	"runtime"
+
+	"github.com/rancher-sandbox/rancher-desktop/src/go/rdctl/pkg/client"
+	"github.com/rancher-sandbox/rancher-desktop/src/go/rdctl/pkg/shell"
+)
+
+type interfaceInfo struct {
+	InterfaceName string `json:"ifname"`
+	Flags         []string
+	State         string `json:"operstate"`
+	MACAddress    string `json:"address"`
+	Addresses     []struct {
+		Family       string
+		Local        string
+		PrefixLength uint `json:"prefixlen"`
+		Broadcast    string
+		Scope        string
+	} `json:"addr_info"`
+}
+
+func getIPAddress(ctx context.Context, result *Info, _ client.RDClient) error {
+	cmd, err := shell.SpawnCommand(ctx, "ip", "-json", "address", "show")
+	if err != nil {
+		return err
+	}
+	var buf bytes.Buffer
+	cmd.Stdout = &buf
+	cmd.Stderr = os.Stderr
+	if err := cmd.Run(); err != nil {
+		return err
+	}
+
+	var interfaces []interfaceInfo
+	if err := json.Unmarshal(buf.Bytes(), &interfaces); err != nil {
+		return err
+	}
+
+	// The list of interface names to try, varying by OS.
+	interfaceNames := map[string][]string{
+		"darwin":  {"rd0", "vznat", "rd1", "eth0"},
+		"linux":   {"eth0"},
+		"windows": {"eth0"},
+	}[runtime.GOOS]
+
+	for _, ifaceName := range interfaceNames {
+		for _, iface := range interfaces {
+			if iface.InterfaceName != ifaceName {
+				continue
+			}
+			for _, addr := range iface.Addresses {
+				if addr.Family == "inet" && addr.Scope == "global" {
+					result.IPAddress = addr.Local
+					return nil
+				}
+			}
+		}
+	}
+
+	return fmt.Errorf("failed to find IP address")
+}
+
+func init() {
+	register("ip-address", getIPAddress)
+}

src/go/rdctl/pkg/info/struct.go

@@ -9,7 +9,8 @@ import (
 // An Info describes the output the user will receive when running `rdctl info`
 // with no special options.
 type Info struct {
-	Version string `json:"version"`
+	Version   string `json:"version" help:"Rancher Desktop application version"`
+	IPAddress string `json:"ip-address" help:"IP address to use to contact the VM"`
 }
 
 // HandlerFunc is the generic interface to populate the [Info] result structure.