bring back last_seen in database (#2579)

* db: add back last_seen to the database

Fixes #2574

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

* integration: ensure last_seen is set

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

---------

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

hscontrol/app.go

@@ -145,7 +145,7 @@ func NewHeadscale(cfg *types.Config) (*Headscale, error) {
 		registrationCache,
 	)
 	if err != nil {
-		return nil, err
+		return nil, fmt.Errorf("new database: %w", err)
 	}
 
 	app.ipAlloc, err = db.NewIPAllocator(app.db, cfg.PrefixV4, cfg.PrefixV6, cfg.IPAllocation)
@@ -160,7 +160,7 @@ func NewHeadscale(cfg *types.Config) (*Headscale, error) {
 	})
 
 	if err = app.loadPolicyManager(); err != nil {
-		return nil, fmt.Errorf("failed to load ACL policy: %w", err)
+		return nil, fmt.Errorf("loading ACL policy: %w", err)
 	}
 
 	var authProvider AuthProvider

hscontrol/db/db.go

@@ -672,7 +672,24 @@ AND auth_key_id NOT IN (
 			{
 				ID: "202502171819",
 				Migrate: func(tx *gorm.DB) error {
-					_ = tx.Migrator().DropColumn(&types.Node{}, "last_seen")
+					// This migration originally removed the last_seen column
+					// from the node table, but it was added back in
+					// 202505091439.
+					return nil
+				},
+				Rollback: func(db *gorm.DB) error { return nil },
+			},
+			// Add back last_seen column to node table.
+			{
+				ID: "202505091439",
+				Migrate: func(tx *gorm.DB) error {
+					// Add back last_seen column to node table if it does not exist.
+					// This is a workaround for the fact that the last_seen column
+					// was removed in the 202502171819 migration, but only for some
+					// beta testers.
+					if !tx.Migrator().HasColumn(&types.Node{}, "last_seen") {
+						_ = tx.Migrator().AddColumn(&types.Node{}, "last_seen")
+					}
 
 					return nil
 				},

hscontrol/db/node.go

@@ -251,6 +251,20 @@ func SetApprovedRoutes(
 	return nil
 }
 
+// SetLastSeen sets a node's last seen field indicating that we
+// have recently communicating with this node.
+func (hsdb *HSDatabase) SetLastSeen(nodeID types.NodeID, lastSeen time.Time) error {
+	return hsdb.Write(func(tx *gorm.DB) error {
+		return SetLastSeen(tx, nodeID, lastSeen)
+	})
+}
+
+// SetLastSeen sets a node's last seen field indicating that we
+// have recently communicating with this node.
+func SetLastSeen(tx *gorm.DB, nodeID types.NodeID, lastSeen time.Time) error {
+	return tx.Model(&types.Node{}).Where("id = ?", nodeID).Update("last_seen", lastSeen).Error
+}
+
 // RenameNode takes a Node struct and a new GivenName for the nodes
 // and renames it. If the name is not unique, it will return an error.
 func RenameNode(tx *gorm.DB,

hscontrol/poll.go

@@ -409,6 +409,10 @@ func (h *Headscale) updateNodeOnlineStatus(online bool, node *types.Node) {
 		change.LastSeen = &now
 	}
 
+	if node.LastSeen != nil {
+		h.db.SetLastSeen(node.ID, *node.LastSeen)
+	}
+
 	ctx := types.NotifyCtx(context.Background(), "poll-nodeupdate-onlinestatus", node.Hostname)
 	h.nodeNotifier.NotifyWithIgnore(ctx, types.UpdatePeerPatch(change), node.ID)
 }

hscontrol/types/node.go

@@ -98,11 +98,7 @@ type Node struct {
 
 	// LastSeen is when the node was last in contact with
 	// headscale. It is best effort and not persisted.
-	LastSeen *time.Time `gorm:"-"`
-
-	// DEPRECATED: Use the ApprovedRoutes field instead.
-	// TODO(kradalby): remove when ApprovedRoutes is used all over the code.
-	// Routes []Route `gorm:"constraint:OnDelete:CASCADE;"`
+	LastSeen *time.Time `gorm:"column:last_seen"`
 
 	// ApprovedRoutes is a list of routes that the node is allowed to announce
 	// as a subnet router. They are not necessarily the routes that the node