Function init_logging 

pub fn init_logging(
    settings: &LoggingSettings,
    log_dir: PathBuf,
) -> Result<(), Error>

Initializes the logging system with JSON output and optional OpenTelemetry export.

This function sets up the complete logging infrastructure:

• Creates the log directory if it doesn’t exist
• Cleans up old log files based on retention policy
• Configures a rolling file appender with non-blocking I/O
• Applies log level filtering from settings or environment
• Sets up JSON formatting for structured logs
• Initializes tracing export if the tracing feature is enabled
• Bridges log:: records (e.g. from pyroscope-rs) into the tracing pipeline so they appear in Loki alongside tracing events via the tracing-log layer automatically enabled by tracing-subscriber.

The function should only be called once at application startup. The logging system remains active until shutdown_logging() is called.

Arguments

• settings - Logging configuration including level, directory name, and retention settings.
• log_dir - Absolute path to the directory where log files are written. The caller is responsible for computing this from Device::data_path so that logs land on the SD card when one is present. Pass CURRENT_DEVICE.data_path(&settings.directory) at call sites.

Returns

Returns Ok(()) on successful initialization.

Errors

Returns an error if:

• The log directory cannot be created
• Log file cleanup fails
• The rolling file appender cannot be initialized
• The tracing subscriber cannot be initialized
• OpenTelemetry initialization fails (when otel feature is enabled)

Example

use cadmus_core::device::CURRENT_DEVICE;
use cadmus_core::settings::LoggingSettings;
use cadmus_core::logging::init_logging;

let settings = LoggingSettings {
    enabled: true,
    level: "debug".to_string(),
    max_files: 5,
    directory: "logs".into(),
    otlp_endpoint: Some("http://localhost:4318".to_string()),
    pyroscope_endpoint: None,
    enable_kern_log: false,
    enable_dbus_log: false,
};

let log_dir = CURRENT_DEVICE.data_path(&settings.directory);
init_logging(&settings, log_dir)?;