ipn/conf: support RemoteConfig in the config file

Add ConfigVAlpha.RemoteConfig so a user-data/cloud-init config can
delegate remote control to the tailnet admin (see Prefs.RemoteConfig).

Updates #1866

Signed-off-by: Kristoffer Dalby <kristoffer@tailscale.com>

gokrazy/README.md

@@ -92,7 +92,9 @@ single AMI supports two ways of joining a tailnet:
   ```
 
   A config present in user-data locks the CLI (`tailscale set`/`up` are
-  rejected) unless it sets `"Locked": false`.
+  rejected) unless it sets `"Locked": false`. Add `"RemoteConfig": true` to
+  hand full remote management of the node to the tailnet admin (see
+  `Prefs.RemoteConfig`) — appropriate for admin-owned fleet devices.
 
 - **Interactive (serial console):** launch the AMI with *no* user-data. The
   `optional:` prefix means the missing config is not an error, so `tailscaled`

ipn/conf.go

@@ -47,6 +47,7 @@ type ConfigVAlpha struct {
 	RunSSHServer    opt.Bool         `json:",omitempty"` // Tailscale SSH
 	RunWebClient    opt.Bool         `json:",omitempty"`
 	ShieldsUp       opt.Bool         `json:",omitempty"`
+	RemoteConfig    opt.Bool         `json:",omitzero"` // delegate full remote control to the tailnet admin; see Prefs.RemoteConfig
 	AutoUpdate      *AutoUpdatePrefs `json:",omitempty"`
 	ServeConfigTemp *ServeConfig     `json:",omitempty"` // TODO(bradfitz,maisem): make separate stable type for this
 
@@ -167,6 +168,10 @@ func (c *ConfigVAlpha) ToPrefs() (MaskedPrefs, error) {
 		mp.ShieldsUp = c.ShieldsUp.EqualBool(true)
 		mp.ShieldsUpSet = true
 	}
+	if c.RemoteConfig != "" {
+		mp.RemoteConfig = c.RemoteConfig.EqualBool(true)
+		mp.RemoteConfigSet = true
+	}
 	if c.AutoUpdate != nil {
 		mp.AutoUpdate = *c.AutoUpdate
 		mp.AutoUpdateSet = AutoUpdatePrefsMask{ApplySet: true, CheckSet: true}

ipn/conf_test.go

@@ -186,3 +186,28 @@ func TestConfigVAlphaToPrefs(t *testing.T) {
 		})
 	}
 }
+
+func TestConfigVAlphaToPrefsRemoteConfig(t *testing.T) {
+	for name, tt := range map[string]struct {
+		cfg     ConfigVAlpha
+		wantSet bool
+		wantVal bool
+	}{
+		"absent": {ConfigVAlpha{Version: "alpha0"}, false, false},
+		"true":   {ConfigVAlpha{Version: "alpha0", RemoteConfig: "true"}, true, true},
+		"false":  {ConfigVAlpha{Version: "alpha0", RemoteConfig: "false"}, true, false},
+	} {
+		t.Run(name, func(t *testing.T) {
+			mp, err := tt.cfg.ToPrefs()
+			if err != nil {
+				t.Fatal(err)
+			}
+			if mp.RemoteConfigSet != tt.wantSet {
+				t.Errorf("RemoteConfigSet = %v; want %v", mp.RemoteConfigSet, tt.wantSet)
+			}
+			if mp.RemoteConfig != tt.wantVal {
+				t.Errorf("RemoteConfig = %v; want %v", mp.RemoteConfig, tt.wantVal)
+			}
+		})
+	}
+}