Keeps varlink connection open for the HTTP 1.1 connection. one varlink call per HTTP POST, and stream back results
$ go run .
2026/03/02 12:45:42 connecting to /run/systemd/userdb/io.systemd.Multiplexer
2026/03/02 12:45:42 io.systemd.UserDatabase.GetUserRecord
2026/03/02 12:45:42 io.systemd.UserDatabase.GetMemberships
2026/03/02 12:45:42 closing /run/systemd/userdb/io.systemd.Multiplexer