An opinionated Rust tracing-subscriber configuration with a focus on readability.
Serif is my take on the best way to configure tracing-subscriber for use in command-line
applications, with an emphasis on readability of the main log messages. The tracing span scope,
event target, and additional metadata is all rendered with dimmed colors, making the main message
stand out quickly. Or at least it does on the Solarized Dark colorscheme that I prefer.
Serif uses EnvFilter for filtering using the RUST_LOG environment variable, with a default
level of INFO if not otherwise configured.
Serif sets up FmtSubscriber and EnvFilter in a unified configuration. Basically this is all
to make my life easier migrating from env_logger.
All you need is a single dependency in Cargo.toml and a single builder chain to set up the global
default tracing subscriber. For convenience, serif re-exports tracing and provides the common
log macros in serif::macros.
use serif::macros::*;
use serif::tracing::Level;
fn main() {
serif::Config::new() // create config builder
.with_default(Level::DEBUG) // the default otherwise is INFO
.init(); // finalize and register with tracing
info!("Hello World!");
do_stuff();
debug!("Finished doing stuff");
}For more advanced use-cases, Serif provides EventFormatter which implements FormatEvent, and
FieldFormatter which implements FormatFields. These objects can be passed to
a SubscriberBuilder along with whatever other options are desired.
By default, Serif enables ANSI coloring when the output file descriptor (stdout or stderr) is a TTY
and the environment variable NO_COLOR is either unset or empty. At the moment, the specific color
styles are not customizable.
A note to advanced users configuring a SubscriberBuilder manually: EventFormatter and
FieldFormatter do not track whether ANSI colors are enabled directly, instead they obtain this
from the Writer that's passed to various methods. Call SubscriberBuilder::with_ansi to
configure coloring in custom usage.
Serif is released under the Apache 2.0 license.
Additionally, heavy inspiration has been taken from the implementation of
tracing-subscriber, which is
released under the MIT license.