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

tests for that feature.

Other fixes: clean up a few typos in comments. Fix a bug that caused the
tests to run four times each. Be more consistent in the use of log
rather than fmt to print errors and notices.

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"),