Function init_logging 

pub fn init_logging(crate_name: &str)

Logs to stderr: crate_name’s own messages, this crate’s (serving, internal errors) and each request, at info, unless RUST_LOG says otherwise. LOG_FORMAT=json writes a JSON object a line, for a log collector, and OTEL_EXPORTER_OTLP_ENDPOINT sends traces to an OpenTelemetry collector; see observe.