remove username from magicdns names

This commit removes the username from magicDNS names.
This is in preparation of fixing tags, which currently is
not correctly disassociated from users when added. With the
current behaviour, fixing tagged devices would break the
MagicDNS behaviour.

This brings headscale to use the same behaviour of tailscale.

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

CHANGELOG.md

@@ -40,6 +40,10 @@ after improving the test harness as part of adopting [#1460](https://github.com/
 - Prefixes are now defined per v4 and v6 range. [#1756](https://github.com/juanfont/headscale/pull/1756)
   - `ip_prefixes` option is now `prefixes.v4` and `prefixes.v6`
   - `prefixes.allocation` can be set to assign IPs at `sequential` or `random`. [#1869](https://github.com/juanfont/headscale/pull/1869)
+- MagicDNS domains no longer contain usernames []()
+  - This is in preperation to fix Headscales implementation of tags which currently does not correctly remove the link between a tagged device and a user. As tagged devices will not have a user, this will require a change to the DNS generation, removing the username, see [#1369](https://github.com/juanfont/headscale/issues/1369) for more information.
+  - `use_username_in_magic_dns` can be used to turn this behaviour on again, but note that this option _will be removed_ when tags are fixed.
+  - This option brings Headscales behaviour in line with Tailscale.
 
 ### Changes
 

config-example.yaml

@@ -261,6 +261,15 @@ dns_config:
   # Only works if there is at least a nameserver defined.
   magic_dns: true
 
+  # DEPRECATED
+  # Use the username as part of the DNS name for nodes, with this option enabled:
+  # node1.username.example.com
+  # while when this is disabled:
+  # node1.example.com
+  # This is a legacy option as Headscale has have this wrongly implemented
+  # while in upstream Tailscale, the username is not included.
+  use_username_in_magic_dns: false
+
   # Defines the base domain to create the hostnames for MagicDNS.
   # `base_domain` must be a FQDNs, without the trailing dot.
   # The FQDN of the hosts will be

hscontrol/mapper/mapper.go

@@ -122,37 +122,41 @@ func generateUserProfiles(
 }
 
 func generateDNSConfig(
-	base *tailcfg.DNSConfig,
+	cfg *types.Config,
 	baseDomain string,
 	node *types.Node,
 	peers types.Nodes,
 ) *tailcfg.DNSConfig {
-	dnsConfig := base.Clone()
+	if cfg.DNSConfig == nil {
+		return nil
+	}
 
-	// if MagicDNS is enabled
-	if base != nil && base.Proxied {
-		// Only inject the Search Domain of the current user
-		// shared nodes should use their full FQDN
-		dnsConfig.Domains = append(
-			dnsConfig.Domains,
-			fmt.Sprintf(
-				"%s.%s",
-				node.User.Name,
-				baseDomain,
-			),
-		)
+	dnsConfig := cfg.DNSConfig.Clone()
 
-		userSet := mapset.NewSet[types.User]()
-		userSet.Add(node.User)
-		for _, p := range peers {
-			userSet.Add(p.User)
-		}
-		for _, user := range userSet.ToSlice() {
-			dnsRoute := fmt.Sprintf("%v.%v", user.Name, baseDomain)
-			dnsConfig.Routes[dnsRoute] = nil
+	// if MagicDNS is enabled
+	if dnsConfig.Proxied {
+		if cfg.DNSUserNameInMagicDNS {
+			// Only inject the Search Domain of the current user
+			// shared nodes should use their full FQDN
+			dnsConfig.Domains = append(
+				dnsConfig.Domains,
+				fmt.Sprintf(
+					"%s.%s",
+					node.User.Name,
+					baseDomain,
+				),
+			)
+
+			userSet := mapset.NewSet[types.User]()
+			userSet.Add(node.User)
+			for _, p := range peers {
+				userSet.Add(p.User)
+			}
+			for _, user := range userSet.ToSlice() {
+				dnsRoute := fmt.Sprintf("%v.%v", user.Name, baseDomain)
+				dnsConfig.Routes[dnsRoute] = nil
+			}
 		}
-	} else {
-		dnsConfig = base
 	}
 
 	addNextDNSMetadata(dnsConfig.Resolvers, node)

hscontrol/types/config.go

@@ -63,7 +63,8 @@ type Config struct {
 	ACMEURL   string
 	ACMEEmail string
 
-	DNSConfig *tailcfg.DNSConfig
+	DNSConfig             *tailcfg.DNSConfig
+	DNSUserNameInMagicDNS bool
 
 	UnixSocket           string
 	UnixSocketPermission fs.FileMode
@@ -203,6 +204,7 @@ func LoadConfig(path string, isFile bool) error {
 
 	viper.SetDefault("dns_config", nil)
 	viper.SetDefault("dns_config.override_local_dns", true)
+	viper.SetDefault("dns_config.use_username_in_magic_dns", false)
 
 	viper.SetDefault("derp.server.enabled", false)
 	viper.SetDefault("derp.server.stun.enabled", true)
@@ -561,6 +563,13 @@ func GetDNSConfig() (*tailcfg.DNSConfig, string) {
 			baseDomain = "headscale.net" // does not really matter when MagicDNS is not enabled
 		}
 
+		if !viper.GetBool("dns_config.use_username_in_magic_dns") {
+			dnsConfig.Domains = []string{baseDomain}
+		} else {
+			log.Warn().Msg("DNS: Usernames in DNS has been deprecated, this option will be remove in future versions")
+			log.Warn().Msg("DNS: see 0.23.0 changelog for more information.")
+		}
+
 		if domains := viper.GetStringSlice("dns_config.domains"); len(domains) > 0 {
 			dnsConfig.Domains = append(dnsConfig.Domains, domains...)
 		}
@@ -708,7 +717,8 @@ func GetHeadscaleConfig() (*Config, error) {
 
 		TLS: GetTLSConfig(),
 
-		DNSConfig: dnsConfig,
+		DNSConfig:             dnsConfig,
+		DNSUserNameInMagicDNS: viper.GetBool("dns_config.use_username_in_magic_dns"),
 
 		ACMEEmail: viper.GetString("acme_email"),
 		ACMEURL:   viper.GetString("acme_url"),