Function setup_logger 

pub fn setup_logger()

Install the tracing subscriber used by every example and binary in the crate.

The level is read from the DERIBIT_LOG_LEVEL environment variable once, on the first call. Recognised values: TRACE, DEBUG, INFO, WARN, ERROR. Anything else (or an unset variable) defaults to INFO.

The subscriber is registered as the process-global default via tracing::subscriber::set_global_default, which tracing allows only once per process. A Once guard makes subsequent calls to this function safe: they return immediately without touching the already-installed subscriber, so applications that wire logging from multiple entry points (tests, libs, main) do not race.

Changing DERIBIT_LOG_LEVEL after the first call has no effect — tracing does not support replacing the global default at runtime.

Example

use deribit_websocket::utils::setup_logger;

// Set log level via environment variable (unsafe in Rust 2024 edition)
unsafe {
    std::env::set_var("DERIBIT_LOG_LEVEL", "DEBUG");
}

// Initialize the logger
setup_logger();

// Now you can use tracing macros
tracing::info!("Logger initialized");