cmd/tailscale,ipn: add auto-update flags and prefs (#8861)

The flags are hidden for now. Adding propagation to tailscaled and
persistence only. The prefs field is wrapped in a struct to allow for
future expansion (like update schedule).

Updates #6907

Signed-off-by: Andrew Lytvynov <awly@tailscale.com>

ipn/prefs.go

@@ -196,6 +196,10 @@ type Prefs struct {
 	// and CLI.
 	ProfileName string `json:",omitempty"`
 
+	// AutoUpdate sets the auto-update preferences for the node agent. See
+	// AutoUpdatePrefs docs for more details.
+	AutoUpdate AutoUpdatePrefs
+
 	// The Persist field is named 'Config' in the file for backward
 	// compatibility with earlier versions.
 	// TODO(apenwarr): We should move this out of here, it's not a pref.
@@ -204,6 +208,18 @@ type Prefs struct {
 	Persist *persist.Persist `json:"Config"`
 }
 
+// AutoUpdatePrefs are the auto update settings for the node agent.
+type AutoUpdatePrefs struct {
+	// Check specifies whether background checks for updates are enabled. When
+	// enabled, tailscaled will periodically check for available updates and
+	// notify the user about them.
+	Check bool
+	// Apply specifies whether background auto-updates are enabled. When
+	// enabled, tailscaled will apply available updates in the background.
+	// Check must also be set when Apply is set.
+	Apply bool
+}
+
 // MaskedPrefs is a Prefs with an associated bitmask of which fields are set.
 type MaskedPrefs struct {
 	Prefs
@@ -229,6 +245,7 @@ type MaskedPrefs struct {
 	NetfilterModeSet          bool `json:",omitempty"`
 	OperatorUserSet           bool `json:",omitempty"`
 	ProfileNameSet            bool `json:",omitempty"`
+	AutoUpdateSet             bool `json:",omitempty"`
 }
 
 // ApplyEdits mutates p, assigning fields from m.Prefs for each MaskedPrefs
@@ -284,6 +301,12 @@ func (m *MaskedPrefs) Pretty() string {
 			if v.Type().Elem().Kind() == reflect.String {
 				return "%s=%q"
 			}
+		case reflect.Struct:
+			return "%s=%+v"
+		case reflect.Pointer:
+			if v.Type().Elem().Kind() == reflect.Struct {
+				return "%s=%+v"
+			}
 		}
 		return "%s=%v"
 	}
@@ -360,6 +383,7 @@ func (p *Prefs) pretty(goos string) string {
 	if p.OperatorUser != "" {
 		fmt.Fprintf(&sb, "op=%q ", p.OperatorUser)
 	}
+	sb.WriteString(p.AutoUpdate.Pretty())
 	if p.Persist != nil {
 		sb.WriteString(p.Persist.Pretty())
 	} else {
@@ -414,7 +438,18 @@ func (p *Prefs) Equals(p2 *Prefs) bool {
 		compareIPNets(p.AdvertiseRoutes, p2.AdvertiseRoutes) &&
 		compareStrings(p.AdvertiseTags, p2.AdvertiseTags) &&
 		p.Persist.Equals(p2.Persist) &&
-		p.ProfileName == p2.ProfileName
+		p.ProfileName == p2.ProfileName &&
+		p.AutoUpdate == p2.AutoUpdate
+}
+
+func (au AutoUpdatePrefs) Pretty() string {
+	if au.Apply {
+		return "update=on "
+	}
+	if au.Check {
+		return "update=check "
+	}
+	return "update=off "
 }
 
 func compareIPNets(a, b []netip.Prefix) bool {
@@ -459,6 +494,10 @@ func NewPrefs() *Prefs {
 		CorpDNS:          true,
 		WantRunning:      false,
 		NetfilterMode:    preftype.NetfilterOn,
+		AutoUpdate: AutoUpdatePrefs{
+			Check: true,
+			Apply: false,
+		},
 	}
 }