Make write-ahead-log default and configurable for sqlite (#1985)

* correctly enable WAL log for sqlite

this commit makes headscale correctly enable write-ahead-log for
sqlite and adds an option to turn it on and off.

WAL is enabled by default and should make sqlite perform a lot better,
even further eliminating the need to use postgres.

It also adds a couple of other useful defaults.

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

* update changelog

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

---------

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

hscontrol/db/db.go

@@ -434,13 +434,29 @@ func openDB(cfg types.DatabaseConfig) (*gorm.DB, error) {
 			Msg("Opening database")
 
 		db, err := gorm.Open(
-			sqlite.Open(cfg.Sqlite.Path+"?_synchronous=1&_journal_mode=WAL"),
+			sqlite.Open(cfg.Sqlite.Path),
 			&gorm.Config{
 				Logger: dbLogger,
 			},
 		)
 
-		db.Exec("PRAGMA foreign_keys=ON")
+		if err := db.Exec(`
+			PRAGMA foreign_keys=ON;
+			PRAGMA busy_timeout=10000;
+			PRAGMA auto_vacuum=INCREMENTAL;
+			PRAGMA synchronous=NORMAL;
+			`).Error; err != nil {
+			return nil, fmt.Errorf("enabling foreign keys: %w", err)
+		}
+
+		if cfg.Sqlite.WriteAheadLog {
+			if err := db.Exec(`
+				PRAGMA journal_mode=WAL;
+				PRAGMA wal_autocheckpoint=0;
+				`).Error; err != nil {
+				return nil, fmt.Errorf("setting WAL mode: %w", err)
+			}
+		}
 
 		// The pure Go SQLite library does not handle locking in
 		// the same way as the C based one and we cant use the gorm