I'm using Rust tracing-journald and tracing crate for logging to journalctl in my application. The log events render correctly to journalctl but spans do not appear to journald by default and are only available in verbose mode journalctl -t test-service -n 2 -f -o verbose mode.

ri 2025-01-31 00:41:57.462458 UTC [s=78f20397c39b44be8df7e5034ecc9ab2;i=43a3cb;b=55a752e1c04a416ba07b4942ee50f0e1;m=27cc1cc3c2;t=62cf5cf5736e5;x=41ec2f15bdf0db45]
    _TRANSPORT=journal
    _UID=0
    .
    .
    CODE_LINE=73
    PRIORITY=3
    SPAN_NAME=my_span
    SPAN_TARGET=log
    SPAN_CODE_FILE=src/main.rs
    SPAN_CODE_LINE=69
    MESSAGE=17 My error message

I would prefer them to be formatted as JSON and appear as log to journalctl directly without verbose argument.

{"timestamp":"2025-01-31T01:42:56.385502Z","level":"INFO","fields":{"message":"close","time.busy":"6.37ms","time.idle":"2.76ms"},"target":"zbus::handshake","span":{"command":"Auth(Some(External), Some([48]))","name":"write_command"}}

I added a custom formatting layer before journald layer but it it doesn't work and spans appear on stdout instead of journald

// pseudo code
        let journald_layer = tracing_journald::layer()
            .map_err(TelemetryStackBuildError::JournalDError)?
            .with_syslog_identifier(service_name.to_owned());

        let span_formatter = fmt::layer()
                    .with_span_events(FmtSpan::CLOSE)
                    .flatten_event(false)
                    .with_span_list(false);

        let subscriber = tracing_subscriber::registry()
            .with(journald_layer)
            .with(logcontrol_layer)
            .with(span_formatter);

Please suggest how can I achieve log spans directly to journalctl?