Merge branch 'main' into registration_cache_fix

CHANGELOG.md

@@ -26,6 +26,7 @@ Please read the [PR description](https://github.com/juanfont/headscale/pull/2617
 for more technical details about the issues and solutions.
 
 **SQLite Database Backup Example:**
+
 ```bash
 # Stop headscale
 systemctl stop headscale
@@ -41,6 +42,13 @@ cp /var/lib/headscale/db.sqlite-shm /var/lib/headscale/db.sqlite-shm.backup
 systemctl start headscale
 ```
 
+### DERPMap update frequency
+
+The default DERPMap update frequency has been changed from 24 hours to 3 hours.
+If you set the `derp.update_frequency` configuration option, it is recommended to change
+it to `3h` to ensure that the headscale instance gets the latest DERPMap updates when
+upstream is changed.
+
 ### BREAKING
 
 - Remove support for 32-bit binaries
@@ -55,6 +63,11 @@ systemctl start headscale
   - **IMPORTANT: Backup your SQLite database before upgrading**
   - Introduces safer table renaming migration strategy
   - Addresses longstanding database integrity issues
+- DERPmap update frequency default changed from 24h to 3h
+  [#2741](https://github.com/juanfont/headscale/pull/2741)
+- DERPmap update mechanism has been improved with retry,
+  and is now failing conservatively, preserving the old map upon failure.
+  [#2741](https://github.com/juanfont/headscale/pull/2741)
 - Add support for `autogroup:member`, `autogroup:tagged`
   [#2572](https://github.com/juanfont/headscale/pull/2572)
 - Remove policy v1 code [#2600](https://github.com/juanfont/headscale/pull/2600)
@@ -72,7 +85,7 @@ systemctl start headscale
   [#2643](https://github.com/juanfont/headscale/pull/2643)
 - OIDC: Use group claim from UserInfo
   [#2663](https://github.com/juanfont/headscale/pull/2663)
-- OIDC: Update user with claims from UserInfo *before* comparing with allowed
+- OIDC: Update user with claims from UserInfo _before_ comparing with allowed
   groups, email and domain [#2663](https://github.com/juanfont/headscale/pull/2663)
 
 ## 0.26.1 (2025-06-06)

config-example.yaml

@@ -105,7 +105,7 @@ derp:
 
     # For better connection stability (especially when using an Exit-Node and DNS is not working),
     # it is possible to optionally add the public IPv4 and IPv6 address to the Derp-Map using:
-    ipv4: 1.2.3.4
+    ipv4: 198.51.100.1
     ipv6: 2001:db8::1
 
   # List of externally available DERP maps encoded in JSON
@@ -128,7 +128,7 @@ derp:
   auto_update_enabled: true
 
   # How often should we check for DERP updates?
-  update_frequency: 24h
+  update_frequency: 3h
 
 # Disables the automatic check for headscale updates on startup
 disable_check_updates: false
@@ -293,8 +293,7 @@ dns:
 
     # Split DNS (see https://tailscale.com/kb/1054/dns/),
     # a map of domains and which DNS server to use for each.
-    split:
+    split: {}
-      {}
       # foo.bar.com:
       #   - 1.1.1.1
       # darp.headscale.net:

derp-example.yaml

@@ -7,9 +7,9 @@ regions:
     nodes:
       - name: 900a
         regionid: 900
-        hostname: myderp.mydomain.no
+        hostname: myderp.example.com
-        ipv4: 123.123.123.123
+        ipv4: 198.51.100.1
-        ipv6: "2604:a880:400:d1::828:b001"
+        ipv6: 2001:db8::1
         stunport: 0
         stunonly: false
         derpport: 0

docs/about/features.md

@@ -19,7 +19,7 @@ provides on overview of Headscale's feature and compatibility with the Tailscale
     - [x] [Exit nodes](../ref/routes.md#exit-node)
 - [x] Dual stack (IPv4 and IPv6)
 - [x] Ephemeral nodes
-- [x] Embedded [DERP server](https://tailscale.com/kb/1232/derp-servers)
+- [x] Embedded [DERP server](../ref/derp.md)
 - [x] Access control lists ([GitHub label "policy"](https://github.com/juanfont/headscale/labels/policy%20%F0%9F%93%9D))
     - [x] ACL management via API
     - [x] Some [Autogroups](https://tailscale.com/kb/1396/targets#autogroups), currently: `autogroup:internet`,

docs/ref/derp.md

@@ -0,0 +1,153 @@
+# DERP
+
+A [DERP (Designated Encrypted Relay for Packets) server](https://tailscale.com/kb/1232/derp-servers) is mainly used to
+relay traffic between two nodes in case a direct connection can't be established. Headscale provides an embedded DERP
+server to ensure seamless connectivity between nodes.
+
+## Configuration
+
+DERP related settings are configured within the `derp` section of the [configuration file](./configuration.md). The
+following sections only use a few of the available settings, check the [example configuration](./configuration.md) for
+all available configuration options.
+
+### Enable embedded DERP
+
+Headscale ships with an embedded DERP server which allows to run your own self-hosted DERP server easily. The embedded
+DERP server is disabled by default and needs to be enabled. In addition, you should configure the public IPv4 and public
+IPv6 address of your Headscale server for improved connection stability:
+
+```yaml title="config.yaml" hl_lines="3-5"
+derp:
+  server:
+    enabled: true
+    ipv4: 198.51.100.1
+    ipv6: 2001:db8::1
+```
+
+Keep in mind that [additional ports are needed to run a DERP server](../setup/requirements.md#ports-in-use). Besides
+relaying traffic, it also uses STUN (udp/3478) to help clients discover their public IP addresses and perform NAT
+traversal. [Check DERP server connectivity](#check-derp-server-connectivity) to see if everything works.
+
+### Remove Tailscale's DERP servers
+
+Once enabled, Headscale's embedded DERP is added to the list of free-to-use [DERP
+servers](https://tailscale.com/kb/1232/derp-servers) offered by Tailscale Inc. To only use Headscale's embedded DERP
+server, disable the loading of the default DERP map:
+
+```yaml title="config.yaml" hl_lines="6"
+derp:
+  server:
+    enabled: true
+    ipv4: 198.51.100.1
+    ipv6: 2001:db8::1
+  urls: []
+```
+
+!!! warning "Single point of failure"
+
+    Removing Tailscale's DERP servers means that there is now just a single DERP server available for clients. This is a
+    single point of failure and could hamper connectivity.
+
+    [Check DERP server connectivity](#check-derp-server-connectivity) with your embedded DERP server before removing
+    Tailscale's DERP servers.
+
+### Customize DERP map
+
+The DERP map offered to clients can be customized with a [dedicated YAML-configuration
+file](https://github.com/juanfont/headscale/blob/main/derp-example.yaml). Typical use-cases involve:
+
+- Running a fleet of [custom DERP servers](https://tailscale.com/kb/1118/custom-derp-servers)
+- Excluding or choosing specific regions from the Tailscale's list of free-to-use [DERP
+  servers](https://tailscale.com/kb/1232/derp-servers)
+
+The following sample `derp.yaml` references two custom regions (`custom-east` with ID 900 and `custom-west` with ID 901)
+with one custom DERP server in each region. Each DERP server offers DERP relay via HTTPS on tcp/443, support for captive
+portal checks via HTTP on tcp/80 and STUN on udp/3478. See the definitions of
+[DERPMap](https://pkg.go.dev/tailscale.com/tailcfg#DERPMap),
+[DERPRegion](https://pkg.go.dev/tailscale.com/tailcfg#DERPRegion) and
+[DERPNode](https://pkg.go.dev/tailscale.com/tailcfg#DERPNode) for all available options.
+
+```yaml title="derp.yaml"
+regions:
+  900:
+    regionid: 900
+    regioncode: custom-east
+    regionname: My region (east)
+    nodes:
+      - name: 900a
+        regionid: 900
+        hostname: derp900a.example.com
+        ipv4: 198.51.100.1
+        ipv6: 2001:db8::1
+        canport80: true
+  901:
+    regionid: 901
+    regioncode: custom-west
+    regionname: My Region (west)
+    nodes:
+      - name: 901a
+        regionid: 901
+        hostname: derp901a.example.com
+        ipv4: 198.51.100.2
+        ipv6: 2001:db8::2
+        canport80: true
+```
+
+Use the following configuration to only serve the two DERP servers from the above `derp.yaml`:
+
+```yaml title="config.yaml" hl_lines="5 6"
+derp:
+  server:
+    enabled: false
+  urls: []
+  paths:
+    - /etc/headscale/derp.yaml
+```
+
+The embedded DERP server can also be enabled and is automatically added to the custom DERP map.
+
+
+### Verify clients
+
+Access to DERP serves can be restricted to nodes that are members of your Tailnet. Relay access is denied for unknown
+clients.
+
+=== "Embedded DERP"
+
+    Client verification is enabled by default.
+
+    ```yaml title="config.yaml" hl_lines="3"
+    derp:
+      server:
+        verify_clients: true
+    ```
+
+=== "3rd-party DERP"
+
+    Tailscale's `derper` provides two parameters to configure client verification:
+
+    - Use the `-verify-client-url` parameter of the `derper` and point it towards the `/verify` endpoint of your
+      Headscale server (e.g `https://headscale.example.com/verify`). The DERP server will query your Headscale instance
+      as soon as a client connects with it to ask whether access should be allowed or denied. Access is allowed if
+      Headscale knows about the connecting client and denied otherwise.
+    - The parameter `-verify-client-url-fail-open` controls what should happen when the DERP server can't reach the
+      Headscale instance. By default, it will allow access if Headscale is unreachable.
+
+## Check DERP server connectivity
+
+Any Tailscale client may be used to introspect the DERP map and to check for connectivity issues with DERP servers.
+
+- Display DERP map: `tailscale debug derp-map`
+- Check connectivity with the embedded DERP[^1]:`tailscale debug derp headscale`
+
+Additional DERP related metrics and information is available via the [metrics and debug
+endpoint](./debug.md#metrics-and-debug-endpoint).
+
+[^1]:
+    This assumes that the default region code of the [configuration file](./configuration.md) is used.
+
+## Limitations
+
+- The embedded DERP server can't be used for Tailscale's captive portal checks as it doesn't support the `/generate_204`
+  endpoint via HTTP on port tcp/80.
+- There are no speed or throughput optimisations, the main purpose is to assist in node connectivity.

docs/ref/integration/reverse-proxy.md

@@ -13,7 +13,7 @@ Running headscale behind a reverse proxy is useful when running multiple applica
 
 The reverse proxy MUST be configured to support WebSockets to communicate with Tailscale clients.
 
-WebSockets support is also required when using the headscale embedded DERP server. In this case, you will also need to expose the UDP port used for STUN (by default, udp/3478). Please check our [config-example.yaml](https://github.com/juanfont/headscale/blob/main/config-example.yaml).
+WebSockets support is also required when using the Headscale [embedded DERP server](../derp.md). In this case, you will also need to expose the UDP port used for STUN (by default, udp/3478). Please check our [config-example.yaml](https://github.com/juanfont/headscale/blob/main/config-example.yaml).
 
 ### Cloudflare
 

docs/ref/integration/tools.md

@@ -13,3 +13,4 @@ This page collects third-party tools, client libraries, and scripts related to h
 | headscalebacktosqlite | [Github](https://github.com/bigbozza/headscalebacktosqlite)     | Migrate headscale from PostgreSQL back to SQLite                     |
 | headscale-pf          | [Github](https://github.com/YouSysAdmin/headscale-pf)           | Populates user groups based on user groups in Jumpcloud or Authentik |
 | headscale-client-go   | [Github](https://github.com/hibare/headscale-client-go)         | A Go client implementation for the Headscale HTTP API.               |
+| headscale-zabbix      | [Github](https://github.com/dblanque/headscale-zabbix)          | A Zabbix Monitoring Template for the Headscale Service.              |

docs/setup/requirements.md

@@ -22,10 +22,10 @@ The ports in use vary with the intended scenario and enabled features. Some of t
 - tcp/443
     - Expose publicly: yes
     - HTTPS, required to make Headscale available to Tailscale clients[^1]
-    - Required if the built-in DERP server is enabled
+    - Required if the [embedded DERP server](../ref/derp.md) is enabled
 - udp/3478
     - Expose publicly: yes
-    - STUN, required if the built-in DERP server is enabled
+    - STUN, required if the [embedded DERP server](../ref/derp.md) is enabled
 - tcp/50443
     - Expose publicly: yes
     - Only required if the gRPC interface is used to [remote-control Headscale](../ref/remote-cli.md).

flake.lock

@@ -20,11 +20,11 @@
     },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1752012998,
+        "lastModified": 1755829505,
-        "narHash": "sha256-Q82Ms+FQmgOBkdoSVm+FBpuFoeUAffNerR5yVV7SgT8=",
+        "narHash": "sha256-4/Jd+LkQ2ssw8luQVkqVs9spDBVE6h/u/hC/tzngsPo=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "2a2130494ad647f953593c4e84ea4df839fbd68c",
+        "rev": "f937f8ecd1c70efd7e9f90ba13dfb400cf559de4",
         "type": "github"
       },
       "original": {

hscontrol/app.go

@@ -17,6 +17,7 @@ import (
 	"syscall"
 	"time"
 
+	"github.com/cenkalti/backoff/v5"
 	"github.com/davecgh/go-spew/spew"
 	"github.com/gorilla/mux"
 	grpcRuntime "github.com/grpc-ecosystem/grpc-gateway/v2/runtime"
@@ -284,12 +285,24 @@ func (h *Headscale) scheduledTasks(ctx context.Context) {
 
 		case <-derpTickerChan:
 			log.Info().Msg("Fetching DERPMap updates")
-			derpMap := derp.GetDERPMap(h.cfg.DERP)
+			derpMap, err := backoff.Retry(ctx, func() (*tailcfg.DERPMap, error) {
+				derpMap, err := derp.GetDERPMap(h.cfg.DERP)
+				if err != nil {
+					return nil, err
+				}
 				if h.cfg.DERP.ServerEnabled && h.cfg.DERP.AutomaticallyAddEmbeddedDerpRegion {
 					region, _ := h.DERPServer.GenerateRegion()
 					derpMap.Regions[region.RegionID] = &region
 				}
 
+				return derpMap, nil
+			}, backoff.WithBackOff(backoff.NewExponentialBackOff()))
+			if err != nil {
+				log.Error().Err(err).Msg("failed to build new DERPMap, retrying later")
+				continue
+			}
+			h.state.SetDERPMap(derpMap)
+
 			h.Change(change.DERPSet)
 
 		case records, ok := <-extraRecordsUpdate:
@@ -516,29 +529,31 @@ func (h *Headscale) Serve() error {
 	h.mapBatcher.Start()
 	defer h.mapBatcher.Close()
 
-	// TODO(kradalby): fix state part.
 	if h.cfg.DERP.ServerEnabled {
 		// When embedded DERP is enabled we always need a STUN server
 		if h.cfg.DERP.STUNAddr == "" {
 			return errSTUNAddressNotSet
 		}
 
-		region, err := h.DERPServer.GenerateRegion()
-		if err != nil {
-			return fmt.Errorf("generating DERP region for embedded server: %w", err)
-		}
-
-		if h.cfg.DERP.AutomaticallyAddEmbeddedDerpRegion {
-			h.state.DERPMap().Regions[region.RegionID] = &region
-		}
-
 		go h.DERPServer.ServeSTUN()
 	}
 
-	if len(h.state.DERPMap().Regions) == 0 {
+	derpMap, err := derp.GetDERPMap(h.cfg.DERP)
+	if err != nil {
+		return fmt.Errorf("failed to get DERPMap: %w", err)
+	}
+
+	if h.cfg.DERP.ServerEnabled && h.cfg.DERP.AutomaticallyAddEmbeddedDerpRegion {
+		region, _ := h.DERPServer.GenerateRegion()
+		derpMap.Regions[region.RegionID] = &region
+	}
+
+	if len(derpMap.Regions) == 0 {
 		return errEmptyInitialDERPMap
 	}
 
+	h.state.SetDERPMap(derpMap)
+
 	// Start ephemeral node garbage collector and schedule all nodes
 	// that are already in the database and ephemeral. If they are still
 	// around between restarts, they will reconnect and the GC will

hscontrol/db/text_serialiser.go

@@ -10,7 +10,7 @@ import (
 )
 
 // Got from https://github.com/xdg-go/strum/blob/main/types.go
-var textUnmarshalerType = reflect.TypeOf((*encoding.TextUnmarshaler)(nil)).Elem()
+var textUnmarshalerType = reflect.TypeFor[encoding.TextUnmarshaler]()
 
 func isTextUnmarshaler(rv reflect.Value) bool {
 	return rv.Type().Implements(textUnmarshalerType)

hscontrol/derp/derp.go

@@ -1,16 +1,22 @@
 package derp
 
 import (
+	"cmp"
 	"context"
 	"encoding/json"
+	"hash/crc64"
 	"io"
 	"maps"
+	"math/rand"
 	"net/http"
 	"net/url"
 	"os"
+	"reflect"
+	"sync"
+	"time"
 
 	"github.com/juanfont/headscale/hscontrol/types"
-	"github.com/rs/zerolog/log"
+	"github.com/spf13/viper"
 	"gopkg.in/yaml.v3"
 	"tailscale.com/tailcfg"
 )
@@ -76,56 +82,85 @@ func mergeDERPMaps(derpMaps []*tailcfg.DERPMap) *tailcfg.DERPMap {
 		maps.Copy(result.Regions, derpMap.Regions)
 	}
 
+	for id, region := range result.Regions {
+		if region == nil {
+			delete(result.Regions, id)
+		}
+	}
+
 	return &result
 }
 
-func GetDERPMap(cfg types.DERPConfig) *tailcfg.DERPMap {
+func GetDERPMap(cfg types.DERPConfig) (*tailcfg.DERPMap, error) {
 	var derpMaps []*tailcfg.DERPMap
 	if cfg.DERPMap != nil {
 		derpMaps = append(derpMaps, cfg.DERPMap)
 	}
 
-	for _, path := range cfg.Paths {
+	for _, addr := range cfg.URLs {
-		log.Debug().
+		derpMap, err := loadDERPMapFromURL(addr)
-			Str("func", "GetDERPMap").
-			Str("path", path).
-			Msg("Loading DERPMap from path")
-		derpMap, err := loadDERPMapFromPath(path)
 		if err != nil {
-			log.Error().
+			return nil, err
-				Str("func", "GetDERPMap").
-				Str("path", path).
-				Err(err).
-				Msg("Could not load DERP map from path")
-
-			break
 		}
 
 		derpMaps = append(derpMaps, derpMap)
 	}
 
-	for _, addr := range cfg.URLs {
+	for _, path := range cfg.Paths {
-		derpMap, err := loadDERPMapFromURL(addr)
+		derpMap, err := loadDERPMapFromPath(path)
-		log.Debug().
-			Str("func", "GetDERPMap").
-			Str("url", addr.String()).
-			Msg("Loading DERPMap from path")
 		if err != nil {
-			log.Error().
+			return nil, err
-				Str("func", "GetDERPMap").
-				Str("url", addr.String()).
-				Err(err).
-				Msg("Could not load DERP map from path")
-
-			break
 		}
 
 		derpMaps = append(derpMaps, derpMap)
 	}
 
 	derpMap := mergeDERPMaps(derpMaps)
+	shuffleDERPMap(derpMap)
 
-	log.Trace().Interface("derpMap", derpMap).Msg("DERPMap loaded")
+	return derpMap, nil
-
+}
-	return derpMap
+
+func shuffleDERPMap(dm *tailcfg.DERPMap) {
+	if dm == nil || len(dm.Regions) == 0 {
+		return
+	}
+
+	for id, region := range dm.Regions {
+		if len(region.Nodes) == 0 {
+			continue
+		}
+
+		dm.Regions[id] = shuffleRegionNoClone(region)
+	}
+}
+
+var crc64Table = crc64.MakeTable(crc64.ISO)
+
+var (
+	derpRandomOnce sync.Once
+	derpRandomInst *rand.Rand
+	derpRandomMu   sync.RWMutex
+)
+
+func derpRandom() *rand.Rand {
+	derpRandomOnce.Do(func() {
+		seed := cmp.Or(viper.GetString("dns.base_domain"), time.Now().String())
+		rnd := rand.New(rand.NewSource(0))
+		rnd.Seed(int64(crc64.Checksum([]byte(seed), crc64Table)))
+		derpRandomInst = rnd
+	})
+	return derpRandomInst
+}
+
+func resetDerpRandomForTesting() {
+	derpRandomMu.Lock()
+	defer derpRandomMu.Unlock()
+	derpRandomOnce = sync.Once{}
+	derpRandomInst = nil
+}
+
+func shuffleRegionNoClone(r *tailcfg.DERPRegion) *tailcfg.DERPRegion {
+	derpRandom().Shuffle(len(r.Nodes), reflect.Swapper(r.Nodes))
+	return r
 }

hscontrol/derp/derp_test.go

@@ -0,0 +1,284 @@
+package derp
+
+import (
+	"testing"
+
+	"github.com/google/go-cmp/cmp"
+	"github.com/spf13/viper"
+	"tailscale.com/tailcfg"
+)
+
+func TestShuffleDERPMapDeterministic(t *testing.T) {
+	tests := []struct {
+		name       string
+		baseDomain string
+		derpMap    *tailcfg.DERPMap
+		expected   *tailcfg.DERPMap
+	}{
+		{
+			name:       "single region with 4 nodes",
+			baseDomain: "test1.example.com",
+			derpMap: &tailcfg.DERPMap{
+				Regions: map[int]*tailcfg.DERPRegion{
+					1: {
+						RegionID:   1,
+						RegionCode: "nyc",
+						RegionName: "New York City",
+						Nodes: []*tailcfg.DERPNode{
+							{Name: "1f", RegionID: 1, HostName: "derp1f.tailscale.com"},
+							{Name: "1g", RegionID: 1, HostName: "derp1g.tailscale.com"},
+							{Name: "1h", RegionID: 1, HostName: "derp1h.tailscale.com"},
+							{Name: "1i", RegionID: 1, HostName: "derp1i.tailscale.com"},
+						},
+					},
+				},
+			},
+			expected: &tailcfg.DERPMap{
+				Regions: map[int]*tailcfg.DERPRegion{
+					1: {
+						RegionID:   1,
+						RegionCode: "nyc",
+						RegionName: "New York City",
+						Nodes: []*tailcfg.DERPNode{
+							{Name: "1g", RegionID: 1, HostName: "derp1g.tailscale.com"},
+							{Name: "1f", RegionID: 1, HostName: "derp1f.tailscale.com"},
+							{Name: "1i", RegionID: 1, HostName: "derp1i.tailscale.com"},
+							{Name: "1h", RegionID: 1, HostName: "derp1h.tailscale.com"},
+						},
+					},
+				},
+			},
+		},
+		{
+			name:       "multiple regions with nodes",
+			baseDomain: "test2.example.com",
+			derpMap: &tailcfg.DERPMap{
+				Regions: map[int]*tailcfg.DERPRegion{
+					10: {
+						RegionID:   10,
+						RegionCode: "sea",
+						RegionName: "Seattle",
+						Nodes: []*tailcfg.DERPNode{
+							{Name: "10b", RegionID: 10, HostName: "derp10b.tailscale.com"},
+							{Name: "10c", RegionID: 10, HostName: "derp10c.tailscale.com"},
+							{Name: "10d", RegionID: 10, HostName: "derp10d.tailscale.com"},
+						},
+					},
+					2: {
+						RegionID:   2,
+						RegionCode: "sfo",
+						RegionName: "San Francisco",
+						Nodes: []*tailcfg.DERPNode{
+							{Name: "2d", RegionID: 2, HostName: "derp2d.tailscale.com"},
+							{Name: "2e", RegionID: 2, HostName: "derp2e.tailscale.com"},
+							{Name: "2f", RegionID: 2, HostName: "derp2f.tailscale.com"},
+						},
+					},
+				},
+			},
+			expected: &tailcfg.DERPMap{
+				Regions: map[int]*tailcfg.DERPRegion{
+					10: {
+						RegionID:   10,
+						RegionCode: "sea",
+						RegionName: "Seattle",
+						Nodes: []*tailcfg.DERPNode{
+							{Name: "10b", RegionID: 10, HostName: "derp10b.tailscale.com"},
+							{Name: "10c", RegionID: 10, HostName: "derp10c.tailscale.com"},
+							{Name: "10d", RegionID: 10, HostName: "derp10d.tailscale.com"},
+						},
+					},
+					2: {
+						RegionID:   2,
+						RegionCode: "sfo",
+						RegionName: "San Francisco",
+						Nodes: []*tailcfg.DERPNode{
+							{Name: "2f", RegionID: 2, HostName: "derp2f.tailscale.com"},
+							{Name: "2e", RegionID: 2, HostName: "derp2e.tailscale.com"},
+							{Name: "2d", RegionID: 2, HostName: "derp2d.tailscale.com"},
+						},
+					},
+				},
+			},
+		},
+		{
+			name:       "large region with many nodes",
+			baseDomain: "test3.example.com",
+			derpMap: &tailcfg.DERPMap{
+				Regions: map[int]*tailcfg.DERPRegion{
+					4: {
+						RegionID:   4,
+						RegionCode: "fra",
+						RegionName: "Frankfurt",
+						Nodes: []*tailcfg.DERPNode{
+							{Name: "4f", RegionID: 4, HostName: "derp4f.tailscale.com"},
+							{Name: "4g", RegionID: 4, HostName: "derp4g.tailscale.com"},
+							{Name: "4h", RegionID: 4, HostName: "derp4h.tailscale.com"},
+							{Name: "4i", RegionID: 4, HostName: "derp4i.tailscale.com"},
+						},
+					},
+				},
+			},
+			expected: &tailcfg.DERPMap{
+				Regions: map[int]*tailcfg.DERPRegion{
+					4: {
+						RegionID:   4,
+						RegionCode: "fra",
+						RegionName: "Frankfurt",
+						Nodes: []*tailcfg.DERPNode{
+							{Name: "4f", RegionID: 4, HostName: "derp4f.tailscale.com"},
+							{Name: "4h", RegionID: 4, HostName: "derp4h.tailscale.com"},
+							{Name: "4g", RegionID: 4, HostName: "derp4g.tailscale.com"},
+							{Name: "4i", RegionID: 4, HostName: "derp4i.tailscale.com"},
+						},
+					},
+				},
+			},
+		},
+		{
+			name:       "same region different base domain",
+			baseDomain: "different.example.com",
+			derpMap: &tailcfg.DERPMap{
+				Regions: map[int]*tailcfg.DERPRegion{
+					4: {
+						RegionID:   4,
+						RegionCode: "fra",
+						RegionName: "Frankfurt",
+						Nodes: []*tailcfg.DERPNode{
+							{Name: "4f", RegionID: 4, HostName: "derp4f.tailscale.com"},
+							{Name: "4g", RegionID: 4, HostName: "derp4g.tailscale.com"},
+							{Name: "4h", RegionID: 4, HostName: "derp4h.tailscale.com"},
+							{Name: "4i", RegionID: 4, HostName: "derp4i.tailscale.com"},
+						},
+					},
+				},
+			},
+			expected: &tailcfg.DERPMap{
+				Regions: map[int]*tailcfg.DERPRegion{
+					4: {
+						RegionID:   4,
+						RegionCode: "fra",
+						RegionName: "Frankfurt",
+						Nodes: []*tailcfg.DERPNode{
+							{Name: "4g", RegionID: 4, HostName: "derp4g.tailscale.com"},
+							{Name: "4i", RegionID: 4, HostName: "derp4i.tailscale.com"},
+							{Name: "4f", RegionID: 4, HostName: "derp4f.tailscale.com"},
+							{Name: "4h", RegionID: 4, HostName: "derp4h.tailscale.com"},
+						},
+					},
+				},
+			},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			viper.Set("dns.base_domain", tt.baseDomain)
+			defer viper.Reset()
+			resetDerpRandomForTesting()
+
+			testMap := tt.derpMap.View().AsStruct()
+			shuffleDERPMap(testMap)
+
+			if diff := cmp.Diff(tt.expected, testMap); diff != "" {
+				t.Errorf("Shuffled DERP map doesn't match expected (-expected +actual):\n%s", diff)
+			}
+		})
+	}
+
+}
+
+func TestShuffleDERPMapEdgeCases(t *testing.T) {
+	tests := []struct {
+		name    string
+		derpMap *tailcfg.DERPMap
+	}{
+		{
+			name:    "nil derp map",
+			derpMap: nil,
+		},
+		{
+			name: "empty derp map",
+			derpMap: &tailcfg.DERPMap{
+				Regions: map[int]*tailcfg.DERPRegion{},
+			},
+		},
+		{
+			name: "region with no nodes",
+			derpMap: &tailcfg.DERPMap{
+				Regions: map[int]*tailcfg.DERPRegion{
+					1: {
+						RegionID:   1,
+						RegionCode: "empty",
+						RegionName: "Empty Region",
+						Nodes:      []*tailcfg.DERPNode{},
+					},
+				},
+			},
+		},
+		{
+			name: "region with single node",
+			derpMap: &tailcfg.DERPMap{
+				Regions: map[int]*tailcfg.DERPRegion{
+					1: {
+						RegionID:   1,
+						RegionCode: "single",
+						RegionName: "Single Node Region",
+						Nodes: []*tailcfg.DERPNode{
+							{Name: "1a", RegionID: 1, HostName: "derp1a.tailscale.com"},
+						},
+					},
+				},
+			},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			shuffleDERPMap(tt.derpMap)
+		})
+	}
+}
+
+
+func TestShuffleDERPMapWithoutBaseDomain(t *testing.T) {
+	viper.Reset()
+	resetDerpRandomForTesting()
+
+	derpMap := &tailcfg.DERPMap{
+		Regions: map[int]*tailcfg.DERPRegion{
+			1: {
+				RegionID:   1,
+				RegionCode: "test",
+				RegionName: "Test Region",
+				Nodes: []*tailcfg.DERPNode{
+					{Name: "1a", RegionID: 1, HostName: "derp1a.test.com"},
+					{Name: "1b", RegionID: 1, HostName: "derp1b.test.com"},
+					{Name: "1c", RegionID: 1, HostName: "derp1c.test.com"},
+					{Name: "1d", RegionID: 1, HostName: "derp1d.test.com"},
+				},
+			},
+		},
+	}
+
+	original := derpMap.View().AsStruct()
+	shuffleDERPMap(derpMap)
+
+	if len(derpMap.Regions) != 1 || len(derpMap.Regions[1].Nodes) != 4 {
+		t.Error("Shuffle corrupted DERP map structure")
+	}
+
+	originalNodes := make(map[string]bool)
+	for _, node := range original.Regions[1].Nodes {
+		originalNodes[node.Name] = true
+	}
+
+	shuffledNodes := make(map[string]bool)
+	for _, node := range derpMap.Regions[1].Nodes {
+		shuffledNodes[node.Name] = true
+	}
+
+	if diff := cmp.Diff(originalNodes, shuffledNodes); diff != "" {
+		t.Errorf("Shuffle changed node set (-original +shuffled):\n%s", diff)
+	}
+}

hscontrol/derp/server/derp_server.go

@@ -276,7 +276,7 @@ func DERPProbeHandler(
 // An example implementation is found here https://derp.tailscale.com/bootstrap-dns
 // Coordination server is included automatically, since local DERP is using the same DNS Name in d.serverURL.
 func DERPBootstrapDNSHandler(
-	derpMap *tailcfg.DERPMap,
+	derpMap tailcfg.DERPMapView,
 ) func(http.ResponseWriter, *http.Request) {
 	return func(
 		writer http.ResponseWriter,
@@ -287,18 +287,18 @@ func DERPBootstrapDNSHandler(
 		resolvCtx, cancel := context.WithTimeout(req.Context(), time.Minute)
 		defer cancel()
 		var resolver net.Resolver
-		for _, region := range derpMap.Regions {
+		for _, region := range derpMap.Regions().All() {
-			for _, node := range region.Nodes { // we don't care if we override some nodes
+			for _, node := range region.Nodes().All() { // we don't care if we override some nodes
-				addrs, err := resolver.LookupIP(resolvCtx, "ip", node.HostName)
+				addrs, err := resolver.LookupIP(resolvCtx, "ip", node.HostName())
 				if err != nil {
 					log.Trace().
 						Caller().
 						Err(err).
-						Msgf("bootstrap DNS lookup failed %q", node.HostName)
+						Msgf("bootstrap DNS lookup failed %q", node.HostName())
 
 					continue
 				}
-				dnsEntries[node.HostName] = addrs
+				dnsEntries[node.HostName()] = addrs
 			}
 		}
 		writer.Header().Set("Content-Type", "application/json")

hscontrol/mapper/batcher_test.go

@@ -10,6 +10,7 @@ import (
 	"time"
 
 	"github.com/juanfont/headscale/hscontrol/db"
+	"github.com/juanfont/headscale/hscontrol/derp"
 	"github.com/juanfont/headscale/hscontrol/state"
 	"github.com/juanfont/headscale/hscontrol/types"
 	"github.com/juanfont/headscale/hscontrol/types/change"
@@ -167,6 +168,12 @@ func setupBatcherWithTestData(t *testing.T, bf batcherFunc, userCount, nodesPerU
 		t.Fatalf("Failed to create state: %v", err)
 	}
 
+	derpMap, err := derp.GetDERPMap(cfg.DERP)
+	assert.NoError(t, err)
+	assert.NotNil(t, derpMap)
+
+	state.SetDERPMap(derpMap)
+
 	// Set up a permissive policy that allows all communication for testing
 	allowAllPolicy := `{
 		"acls": [

hscontrol/mapper/builder.go

@@ -79,7 +79,7 @@ func (b *MapResponseBuilder) WithSelfNode() *MapResponseBuilder {
 
 // WithDERPMap adds the DERP map to the response
 func (b *MapResponseBuilder) WithDERPMap() *MapResponseBuilder {
-	b.resp.DERPMap = b.mapper.state.DERPMap()
+	b.resp.DERPMap = b.mapper.state.DERPMap().AsStruct()
 	return b
 }
 

hscontrol/state/state.go

@@ -10,10 +10,10 @@ import (
 	"net/netip"
 	"os"
 	"strings"
+	"sync/atomic"
 	"time"
 
 	hsdb "github.com/juanfont/headscale/hscontrol/db"
-	"github.com/juanfont/headscale/hscontrol/derp"
 	"github.com/juanfont/headscale/hscontrol/policy"
 	"github.com/juanfont/headscale/hscontrol/policy/matcher"
 	"github.com/juanfont/headscale/hscontrol/routes"
@@ -56,7 +56,7 @@ type State struct {
 	// ipAlloc manages IP address allocation for nodes
 	ipAlloc *hsdb.IPAllocator
 	// derpMap contains the current DERP relay configuration
-	derpMap *tailcfg.DERPMap
+	derpMap atomic.Pointer[tailcfg.DERPMap]
 	// polMan handles policy evaluation and management
 	polMan policy.PolicyManager
 	// registrationCache caches node registration data to reduce database load
@@ -87,8 +87,6 @@ func NewState(cfg *types.Config) (*State, error) {
 		return nil, fmt.Errorf("init ip allocatior: %w", err)
 	}
 
-	derpMap := derp.GetDERPMap(cfg.DERP)
-
 	nodes, err := db.ListNodes()
 	if err != nil {
 		return nil, fmt.Errorf("loading nodes: %w", err)
@@ -108,17 +106,17 @@ func NewState(cfg *types.Config) (*State, error) {
 		return nil, fmt.Errorf("init policy manager: %w", err)
 	}
 
-	return &State{
+	s := &State{
 		cfg: cfg,
 
 		db:                db,
 		ipAlloc:           ipAlloc,
-		// TODO(kradalby): Update DERPMap
-		derpMap:           derpMap,
 		polMan:            polMan,
 		registrationCache: registrationCache,
 		primaryRoutes:     routes.New(),
-	}, nil
+	}
+
+	return s, nil
 }
 
 // Close gracefully shuts down the State instance and releases all resources.
@@ -171,9 +169,14 @@ func policyBytes(db *hsdb.HSDatabase, cfg *types.Config) ([]byte, error) {
 	return nil, fmt.Errorf("%w: %s", ErrUnsupportedPolicyMode, cfg.Policy.Mode)
 }
 
+// SetDERPMap updates the DERP relay configuration.
+func (s *State) SetDERPMap(dm *tailcfg.DERPMap) {
+	s.derpMap.Store(dm)
+}
+
 // DERPMap returns the current DERP relay configuration for peer-to-peer connectivity.
-func (s *State) DERPMap() *tailcfg.DERPMap {
+func (s *State) DERPMap() tailcfg.DERPMapView {
-	return s.derpMap
+	return s.derpMap.Load().View()
 }
 
 // ReloadPolicy reloads the access control policy and triggers auto-approval if changed.
@@ -210,7 +213,6 @@ func (s *State) CreateUser(user types.User) (*types.User, bool, error) {
 	s.mu.Lock()
 	defer s.mu.Unlock()
 
-
 	if err := s.db.DB.Save(&user).Error; err != nil {
 		return nil, false, fmt.Errorf("creating user: %w", err)
 	}

hscontrol/types/config.go

@@ -300,6 +300,7 @@ func LoadConfig(path string, isFile bool) error {
 	viper.SetDefault("derp.server.verify_clients", true)
 	viper.SetDefault("derp.server.stun.enabled", true)
 	viper.SetDefault("derp.server.automatically_add_embedded_derp_region", true)
+	viper.SetDefault("derp.update_frequency", "3h")
 
 	viper.SetDefault("unix_socket", "/var/run/headscale/headscale.sock")
 	viper.SetDefault("unix_socket_permission", "0o770")

mkdocs.yml

@@ -181,6 +181,7 @@ nav:
       - TLS: ref/tls.md
       - ACLs: ref/acls.md
       - DNS: ref/dns.md
+      - DERP: ref/derp.md
       - Remote CLI: ref/remote-cli.md
       - Debug: ref/debug.md
       - Integration: