Add support for ephemeral nodes via a special type of pre-auth key.

README.md

@@ -22,7 +22,7 @@ Headscale implements this coordination server.
 - [x] ~~Multiuser~~ Namespace support
 - [x] Basic routing (advertise & accept)
 - [ ] Share nodes between ~~users~~ namespaces
-- [x] Node registration via pre-auth keys
+- [x] Node registration via pre-auth keys (including reusable keys and ephemeral node support)
 - [X] JSON-formatted output
 - [ ] ACLs
 - [ ] DNS
@@ -97,6 +97,7 @@ Alternatively, you can use Auth Keys to register your machines:
    tailscale up -login-server YOUR_HEADSCALE_URL --authkey YOURAUTHKEY
    ```
 
+If you create an authkey with the `--ephemeral` flag, that key will create ephemeral nodes. This implies that `--reusable` is true.
 
 Please bear in mind that all the commands from headscale support adding `-o json` or `-o json-line`  to get a nicely JSON-formatted output.
 
@@ -124,6 +125,12 @@ Headscale's configuration file is named `config.json` or `config.yaml`. Headscal
 
 `derp_map_path` is the path to the [DERP](https://pkg.go.dev/tailscale.com/derp) map file. If the path is relative, it will be interpreted as relative to the directory the configuration file was read from.
 
+```
+    "ephemeral_node_inactivity_timeout": "30m",
+```
+
+`ephemeral_node_inactivity_timeout` is the timeout after which inactive ephemeral node records will be deleted from the database. The default is 30 minutes. This value must be higher than 65 seconds (the keepalive timeout for the HTTP long poll is 60 seconds, plus a few seconds to avoid race conditions).
+
 ```
     "db_host": "localhost",
     "db_port": 5432,

api.go

@@ -93,7 +93,7 @@ func (h *Headscale) RegistrationHandler(c *gin.Context) {
 	// We do have the updated key!
 	if m.NodeKey == wgcfg.Key(req.NodeKey).HexString() {
 		if m.Registered {
-			log.Println("Client is registered and we have the current key. All clear to /map")
+			log.Printf("[%s] Client is registered and we have the current key. All clear to /map\n", m.Name)
 			resp.AuthURL = ""
 			resp.User = *m.Namespace.toUser()
 			resp.MachineAuthorized = true
@@ -174,7 +174,7 @@ func (h *Headscale) PollNetMapHandler(c *gin.Context) {
 	defer db.Close()
 	var m Machine
 	if db.First(&m, "machine_key = ?", mKey.HexString()).RecordNotFound() {
-		log.Printf("Cannot fingitd machine: %s", err)
+		log.Printf("Ignoring request, cannot find machine with key %s", mKey.HexString())
 		return
 	}
 
@@ -243,29 +243,34 @@ func (h *Headscale) PollNetMapHandler(c *gin.Context) {
 			log.Printf("[%s] Sending data (%d bytes)", m.Name, len(data))
 			_, err := w.Write(data)
 			if err != nil {
-				fmt.Printf("[%s] 🤮 Cannot write data: %s", m.Name, err)
+				log.Printf("[%s] 🤮 Cannot write data: %s", m.Name, err)
 			}
+			now := time.Now().UTC()
+			m.LastSeen = &now
+			db.Save(&m)
 			return true
 
 		case <-update:
 			log.Printf("[%s] Received a request for update", m.Name)
 			data, err := h.getMapResponse(mKey, req, m)
 			if err != nil {
-				fmt.Printf("[%s] 🤮 Cannot get the poll response: %s", m.Name, err)
+				log.Printf("[%s] 🤮 Cannot get the poll response: %s", m.Name, err)
 			}
 			_, err = w.Write(*data)
 			if err != nil {
-				fmt.Printf("[%s] 🤮 Cannot write the poll response: %s", m.Name, err)
+				log.Printf("[%s] 🤮 Cannot write the poll response: %s", m.Name, err)
 			}
 			return true
 
 		case <-c.Request.Context().Done():
 			log.Printf("[%s] 😥 The client has closed the connection", m.Name)
+			now := time.Now().UTC()
+			m.LastSeen = &now
+			db.Save(&m)
 			h.pollMu.Lock()
 			cancelKeepAlive <- []byte{}
 			delete(h.clientsPolling, m.ID)
 			h.pollMu.Unlock()
-
 			return false
 
 		}

app.go

@@ -8,6 +8,7 @@ import (
 	"os"
 	"strings"
 	"sync"
+	"time"
 
 	"github.com/gin-gonic/gin"
 	"golang.org/x/crypto/acme/autocert"
@@ -17,10 +18,11 @@ import (
 
 // Config contains the initial Headscale configuration
 type Config struct {
-	ServerURL      string
-	Addr           string
-	PrivateKeyPath string
-	DerpMap        *tailcfg.DERPMap
+	ServerURL                      string
+	Addr                           string
+	PrivateKeyPath                 string
+	DerpMap                        *tailcfg.DERPMap
+	EphemeralNodeInactivityTimeout time.Duration
 
 	DBtype string
 	DBpath string
@@ -95,6 +97,51 @@ func (h *Headscale) redirect(w http.ResponseWriter, req *http.Request) {
 	http.Redirect(w, req, target, http.StatusFound)
 }
 
+// ExpireEphemeralNodes deletes ephemeral machine records that have not been
+// seen for longer than h.cfg.EphemeralNodeInactivityTimeout
+func (h *Headscale) ExpireEphemeralNodes(milliSeconds int64) {
+	if milliSeconds == 0 {
+		// For testing
+		h.expireEphemeralNodesWorker()
+		return
+	}
+	ticker := time.NewTicker(time.Duration(milliSeconds) * time.Millisecond)
+	for range ticker.C {
+		h.expireEphemeralNodesWorker()
+	}
+}
+
+func (h *Headscale) expireEphemeralNodesWorker() {
+	db, err := h.db()
+	if err != nil {
+		log.Printf("Cannot open DB: %s", err)
+		return
+	}
+	defer db.Close()
+
+	namespaces, err := h.ListNamespaces()
+	if err != nil {
+		log.Printf("Error listing namespaces: %s", err)
+		return
+	}
+	for _, ns := range *namespaces {
+		machines, err := h.ListMachinesInNamespace(ns.Name)
+		if err != nil {
+			log.Printf("Error listing machines in namespace %s: %s", ns.Name, err)
+			return
+		}
+		for _, m := range *machines {
+			if m.AuthKey != nil && m.LastSeen != nil && m.AuthKey.Ephemeral && time.Now().After(m.LastSeen.Add(h.cfg.EphemeralNodeInactivityTimeout)) {
+				log.Printf("[%s] Ephemeral client removed from database\n", m.Name)
+				err = db.Unscoped().Delete(m).Error
+				if err != nil {
+					log.Printf("[%s] 🤮 Cannot delete ephemeral machine from the database: %s", m.Name, err)
+				}
+			}
+		}
+	}
+}
+
 // Serve launches a GIN server with the Headscale API
 func (h *Headscale) Serve() error {
 	r := gin.Default()
@@ -105,7 +152,7 @@ func (h *Headscale) Serve() error {
 	var err error
 	if h.cfg.TLSLetsEncryptHostname != "" {
 		if !strings.HasPrefix(h.cfg.ServerURL, "https://") {
-			fmt.Println("WARNING: listening with TLS but ServerURL does not start with https://")
+			log.Println("WARNING: listening with TLS but ServerURL does not start with https://")
 		}
 
 		m := autocert.Manager{
@@ -136,12 +183,12 @@ func (h *Headscale) Serve() error {
 		}
 	} else if h.cfg.TLSCertPath == "" {
 		if !strings.HasPrefix(h.cfg.ServerURL, "http://") {
-			fmt.Println("WARNING: listening without TLS but ServerURL does not start with http://")
+			log.Println("WARNING: listening without TLS but ServerURL does not start with http://")
 		}
 		err = r.Run(h.cfg.Addr)
 	} else {
 		if !strings.HasPrefix(h.cfg.ServerURL, "https://") {
-			fmt.Println("WARNING: listening with TLS but ServerURL does not start with https://")
+			log.Println("WARNING: listening with TLS but ServerURL does not start with https://")
 		}
 		err = r.RunTLS(h.cfg.Addr, h.cfg.TLSCertPath, h.cfg.TLSKeyPath)
 	}

cmd/headscale/cli/nodes.go

@@ -65,9 +65,9 @@ var ListNodesCmd = &cobra.Command{
 			log.Fatalf("Error getting nodes: %s", err)
 		}
 
-		fmt.Printf("name\t\tlast seen\n")
+		fmt.Printf("name\t\tlast seen\t\tephemeral\n")
 		for _, m := range *machines {
-			fmt.Printf("%s\t%s\n", m.Name, m.LastSeen.Format("2006-01-02 15:04:05"))
+			fmt.Printf("%s\t%s\t%t\n", m.Name, m.LastSeen.Format("2006-01-02 15:04:05"), m.AuthKey.Ephemeral)
 		}
 
 	},

cmd/headscale/cli/preauthkeys.go

@@ -45,10 +45,11 @@ var ListPreAuthKeys = &cobra.Command{
 				expiration = k.Expiration.Format("2006-01-02 15:04:05")
 			}
 			fmt.Printf(
-				"key: %s, namespace: %s, reusable: %v, expiration: %s, created_at: %s\n",
+				"key: %s, namespace: %s, reusable: %v, ephemeral: %v, expiration: %s, created_at: %s\n",
 				k.Key,
 				k.Namespace.Name,
 				k.Reusable,
+				k.Ephemeral,
 				expiration,
 				k.CreatedAt.Format("2006-01-02 15:04:05"),
 			)
@@ -71,6 +72,7 @@ var CreatePreAuthKeyCmd = &cobra.Command{
 			log.Fatalf("Error initializing: %s", err)
 		}
 		reusable, _ := cmd.Flags().GetBool("reusable")
+		ephemeral, _ := cmd.Flags().GetBool("ephemeral")
 
 		e, _ := cmd.Flags().GetString("expiration")
 		var expiration *time.Time
@@ -83,7 +85,7 @@ var CreatePreAuthKeyCmd = &cobra.Command{
 			expiration = &exp
 		}
 
-		k, err := h.CreatePreAuthKey(n, reusable, expiration)
+		k, err := h.CreatePreAuthKey(n, reusable, ephemeral, expiration)
 		if strings.HasPrefix(o, "json") {
 			JsonOutput(k, err, o)
 			return

cmd/headscale/cli/server.go

@@ -17,6 +17,7 @@ var ServeCmd = &cobra.Command{
 		if err != nil {
 			log.Fatalf("Error initializing: %s", err)
 		}
+		go h.ExpireEphemeralNodes(5000)
 		err = h.Serve()
 		if err != nil {
 			log.Fatalf("Error initializing: %s", err)

cmd/headscale/cli/utils.go

@@ -8,6 +8,7 @@ import (
 	"os"
 	"path/filepath"
 	"strings"
+	"time"
 
 	"github.com/juanfont/headscale"
 	"github.com/spf13/viper"
@@ -37,12 +38,22 @@ func getHeadscaleApp() (*headscale.Headscale, error) {
 		log.Printf("Could not load DERP servers map file: %s", err)
 	}
 
+	// Minimum inactivity time out is keepalive timeout (60s) plus a few seconds
+	// to avoid races
+	minInactivityTimeout, _ := time.ParseDuration("65s")
+	if viper.GetDuration("ephemeral_node_inactivity_timeout") <= minInactivityTimeout {
+		err = fmt.Errorf("ephemeral_node_inactivity_timeout (%s) is set too low, must be more than %s\n", viper.GetString("ephemeral_node_inactivity_timeout"), minInactivityTimeout)
+		return nil, err
+	}
+
 	cfg := headscale.Config{
 		ServerURL:      viper.GetString("server_url"),
 		Addr:           viper.GetString("listen_addr"),
 		PrivateKeyPath: absPath(viper.GetString("private_key_path")),
 		DerpMap:        derpMap,
 
+		EphemeralNodeInactivityTimeout: viper.GetDuration("ephemeral_node_inactivity_timeout"),
+
 		DBtype: viper.GetString("db_type"),
 		DBpath: absPath(viper.GetString("db_path")),
 		DBhost: viper.GetString("db_host"),

cmd/headscale/headscale.go

@@ -127,6 +127,7 @@ func main() {
 	cli.PreauthkeysCmd.AddCommand(cli.CreatePreAuthKeyCmd)
 
 	cli.CreatePreAuthKeyCmd.PersistentFlags().Bool("reusable", false, "Make the preauthkey reusable")
+	cli.CreatePreAuthKeyCmd.PersistentFlags().Bool("ephemeral", false, "Preauthkey for ephemeral nodes")
 	cli.CreatePreAuthKeyCmd.Flags().StringP("expiration", "e", "", "Human-readable expiration of the key (30m, 24h, 365d...)")
 
 	headscaleCmd.PersistentFlags().StringP("output", "o", "", "Output format. Empty for human-readable, 'json' or 'json-line'")

config.json.postgres.example

@@ -3,6 +3,7 @@
     "listen_addr": "0.0.0.0:8000",
     "private_key_path": "private.key",
     "derp_map_path": "derp.yaml",
+    "ephemeral_node_inactivity_timeout": "30m",
     "db_type": "postgres",
     "db_host": "localhost",
     "db_port": 5432,

config.json.sqlite.example

@@ -3,6 +3,7 @@
     "listen_addr": "0.0.0.0:8000",
     "private_key_path": "private.key",
     "derp_map_path": "derp.yaml",
+    "ephemeral_node_inactivity_timeout": "30m",
     "db_type": "sqlite3",
     "db_path": "db.sqlite",
     "tls_letsencrypt_hostname": "",

machine.go

@@ -131,7 +131,7 @@ func (m Machine) toNode() (*tailcfg.Node, error) {
 
 	n := tailcfg.Node{
 		ID:         tailcfg.NodeID(m.ID),                               // this is the actual ID
-		StableID:   tailcfg.StableNodeID(strconv.FormatUint(m.ID, 10)), // in headscale, unlike tailcontrol server, IDs are permantent
+		StableID:   tailcfg.StableNodeID(strconv.FormatUint(m.ID, 10)), // in headscale, unlike tailcontrol server, IDs are permanent
 		Name:       hostinfo.Hostname,
 		User:       tailcfg.UserID(m.NamespaceID),
 		Key:        tailcfg.NodeKey(nKey),

machine_test.go

@@ -4,13 +4,11 @@ import (
 	"gopkg.in/check.v1"
 )
 
-var _ = check.Suite(&Suite{})
-
 func (s *Suite) TestGetMachine(c *check.C) {
 	n, err := h.CreateNamespace("test")
 	c.Assert(err, check.IsNil)
 
-	pak, err := h.CreatePreAuthKey(n.Name, false, nil)
+	pak, err := h.CreatePreAuthKey(n.Name, false, false, nil)
 	c.Assert(err, check.IsNil)
 
 	db, err := h.db()

namespaces.go

@@ -119,7 +119,7 @@ func (h *Headscale) ListMachinesInNamespace(name string) (*[]Machine, error) {
 	defer db.Close()
 
 	machines := []Machine{}
-	if err := db.Where(&Machine{NamespaceID: n.ID}).Find(&machines).Error; err != nil {
+	if err := db.Preload("AuthKey").Where(&Machine{NamespaceID: n.ID}).Find(&machines).Error; err != nil {
 		return nil, err
 	}
 	return &machines, nil

namespaces_test.go

@@ -4,8 +4,6 @@ import (
 	"gopkg.in/check.v1"
 )
 
-var _ = check.Suite(&Suite{})
-
 func (s *Suite) TestCreateAndDestroyNamespace(c *check.C) {
 	n, err := h.CreateNamespace("test")
 	c.Assert(err, check.IsNil)
@@ -29,7 +27,7 @@ func (s *Suite) TestDestroyNamespaceErrors(c *check.C) {
 	n, err := h.CreateNamespace("test")
 	c.Assert(err, check.IsNil)
 
-	pak, err := h.CreatePreAuthKey(n.Name, false, nil)
+	pak, err := h.CreatePreAuthKey(n.Name, false, false, nil)
 	c.Assert(err, check.IsNil)
 
 	db, err := h.db()

preauth_keys.go

@@ -18,13 +18,14 @@ type PreAuthKey struct {
 	NamespaceID uint
 	Namespace   Namespace
 	Reusable    bool
+	Ephemeral   bool `gorm:"default:false"`
 
 	CreatedAt  *time.Time
 	Expiration *time.Time
 }
 
 // CreatePreAuthKey creates a new PreAuthKey in a namespace, and returns it
-func (h *Headscale) CreatePreAuthKey(namespaceName string, reusable bool, expiration *time.Time) (*PreAuthKey, error) {
+func (h *Headscale) CreatePreAuthKey(namespaceName string, reusable bool, ephemeral bool, expiration *time.Time) (*PreAuthKey, error) {
 	n, err := h.GetNamespace(namespaceName)
 	if err != nil {
 		return nil, err
@@ -48,6 +49,7 @@ func (h *Headscale) CreatePreAuthKey(namespaceName string, reusable bool, expira
 		NamespaceID: n.ID,
 		Namespace:   *n,
 		Reusable:    reusable,
+		Ephemeral:   ephemeral,
 		CreatedAt:   &now,
 		Expiration:  expiration,
 	}
@@ -94,7 +96,7 @@ func (h *Headscale) checkKeyValidity(k string) (*PreAuthKey, error) {
 		return nil, errorAuthKeyExpired
 	}
 
-	if pak.Reusable { // we don't need to check if has been used before
+	if pak.Reusable || pak.Ephemeral { // we don't need to check if has been used before
 		return &pak, nil
 	}