Add VNC video display including websockets

The other display options open a window always, while the
vnc is more "on demand" by using a separate vnc viewer.

Add localhost and password support for some minimal security,
and websocket support for running novnc in a web browser.

Signed-off-by: Anders F Björklund <[email protected]>

Author: afbjorklund

examples/default.yaml

@@ -215,6 +215,18 @@ video:
   # on performance on macOS hosts: https://gitlab.com/qemu-project/qemu/-/issues/334
   # 🟢 Builtin default: "none"
   display: null
+  # VNC (Virtual Network Computing) is a platform-independent graphical
+  # desktop-sharing system that uses the Remote Frame Buffer protocol (RFB)
+  vnc:
+    # VNC display, e.g., "127.0.0.1:0", "host:d", "unix:path", "none"
+    # By convention the TCP port is 5900+d, connections from any host.
+    display: null
+    # VNC websocket, e.g. "127.0.0.1:5700", "host:port"
+    # By convention the TCP port is 5700+d, connections from any host.
+    websocket: null
+    # VNC password, e.g. "on", "off"
+    # Use QMP to set password: `change-vnc-password password=secret`
+    password: null
 
 # The instance can get routable IP addresses from the vmnet framework using
 # https://github.com/lima-vm/vde_vmnet.

pkg/limayaml/defaults.go

@@ -169,6 +169,25 @@ func FillDefault(y, d, o *LimaYAML, filePath string) {
 		y.Video.Display = pointer.String("none")
 	}
 
+	if y.Video.VNC.Display == nil {
+		y.Video.VNC.Display = d.Video.VNC.Display
+	}
+	if o.Video.VNC.Display != nil {
+		y.Video.VNC.Display = o.Video.VNC.Display
+	}
+	if y.Video.VNC.WebSocket == nil {
+		y.Video.VNC.WebSocket = d.Video.VNC.WebSocket
+	}
+	if o.Video.VNC.WebSocket != nil {
+		y.Video.VNC.WebSocket = o.Video.VNC.WebSocket
+	}
+	if y.Video.VNC.Password == nil {
+		y.Video.VNC.Password = d.Video.VNC.Password
+	}
+	if o.Video.VNC.Password != nil {
+		y.Video.VNC.Password = o.Video.VNC.Password
+	}
+
 	if y.Firmware.LegacyBIOS == nil {
 		y.Firmware.LegacyBIOS = d.Firmware.LegacyBIOS
 	}

pkg/limayaml/limayaml.go

@@ -106,9 +106,16 @@ type Firmware struct {
 	LegacyBIOS *bool `yaml:"legacyBIOS,omitempty" json:"legacyBIOS,omitempty"`
 }
 
+type VNCOptions struct {
+	Display   *string `yaml:"display,omitempty" json:"display,omitempty"`
+	WebSocket *string `yaml:"websocket,omitempty" json:"websocket,omitempty"`
+	Password  *string `yaml:"password,omitempty" json:"password,omitempty"`
+}
+
 type Video struct {
 	// Display is a QEMU display string
-	Display *string `yaml:"display,omitempty" json:"display,omitempty"`
+	Display *string    `yaml:"display,omitempty" json:"display,omitempty"`
+	VNC     VNCOptions `yaml:"vnc" json:"vnc"`
 }
 
 type ProvisionMode = string

pkg/limayaml/validate.go

@@ -88,6 +88,22 @@ func Validate(y LimaYAML, warn bool) error {
 		}
 	}
 
+	if y.Video.VNC.Display != nil {
+		if *y.Video.Display != "none" && *y.Video.Display != "vnc" {
+			return fmt.Errorf("field `video.display` has conflicting type: %q", *y.Video.Display)
+		}
+	}
+	if y.Video.VNC.WebSocket != nil {
+		if y.Video.VNC.Display == nil || *y.Video.VNC.Display == "" {
+			return errors.New("field `video.vnc.display` must be set before video.vnc.websocket")
+		}
+	}
+	if y.Video.VNC.Password != nil {
+		if y.Video.VNC.Display == nil || *y.Video.VNC.Display == "" {
+			return errors.New("field `video.vnc.display` must be set before video.vnc.password")
+		}
+	}
+
 	if *y.CPUs == 0 {
 		return errors.New("field `cpus` must be set")
 	}

pkg/qemu/qemu.go

@@ -509,8 +509,18 @@ func Cmdline(cfg Config) (string, []string, error) {
 	args = append(args, "-device", "virtio-rng-pci")
 
 	// Graphics
-	if *y.Video.Display != "" {
-		args = appendArgsIfNoConflict(args, "-display", *y.Video.Display)
+	if *y.Video.Display != "" || y.Video.VNC.Display != nil {
+		display := *y.Video.Display
+		if y.Video.VNC.Display != nil {
+			display = "vnc=" + *y.Video.VNC.Display
+		}
+		if y.Video.VNC.WebSocket != nil {
+			display += ",websocket=" + *y.Video.VNC.WebSocket
+		}
+		if y.Video.VNC.Password != nil {
+			display += ",password=" + *y.Video.VNC.Password
+		}
+		args = appendArgsIfNoConflict(args, "-display", display)
 	}
 	switch *y.Arch {
 	case limayaml.X8664: