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#![deny(clippy::all, missing_docs)] //! The logging level can be changed by the `RUST_LOG` environment variable just like //! [`env_logger`]. //! //! ## Example //! //! ``` //! use log::{trace, debug, info, warn, error}; //! //! fil_logger::init(); //! //! trace!("some tracing"); //! debug!("debug information"); //! info!("normal information"); //! warn!("a warning"); //! error!("error!"); //! ``` //! //! The default output looks like this (with log level debug): //! //! ```text //! 2019-11-11T21:04:25.685 DEBUG simple > debug information //! 2019-11-11T21:04:25.685 INFO simple > normal information //! 2019-11-11T21:04:25.685 WARN simple > a warning //! 2019-11-11T21:04:25.685 ERROR simple > error! //! ``` //! //! It is also possible to log as JSON, which is more verbose and contains the filename and line //! number as additional information. To enable it, set the environment variable //! `GOLOG_LOG_FMT=json`: //! //! {"level":"debug","ts":"2019-11-11T21:06:45.401+01:00","logger":"simple","caller":"examples/simple.rs:37",",sg":"debug information"}" //! {"level":"info","ts":"2019-11-11T21:06:45.401+01:00","logger":"simple","caller":"examples/simple.rs:38","msg":"//! normal information"}" //! {"level":"warn","ts":"2019-11-11T21:06:45.401+01:00","logger":"simple","caller":"examples/simple.rs:39","msg":"//! a warning"}" //! {"level":"error","ts":"2019-11-11T21:06:45.401+01:00","logger":"simple","caller":"examples/simple.rs:40","msg":"error!"}" //! //! [env_logger]: https://crates.io/crates/env_logger mod single_file_writer; use std::env; use std::fs::File; use atty; use flexi_logger::{self, style, DeferredNow, FormatFunction, LogTarget, Record}; use log::Level; pub use single_file_writer::SingleFileWriter; /// Logs in the same JSON format as [IPFS go-log] does. /// /// One log entry has this structure: /// /// ```json /// { /// "level": "<log-level>", /// "ts":"<timestamp>", /// "logger":"<module-name>", /// "caller":"<source-file>:<line-number>", /// "msg":"<log-message>" /// } /// ``` /// /// [IPFS go-log]: https://github.com/ipfs/go-log pub fn go_log_json_format( writer: &mut dyn std::io::Write, now: &mut DeferredNow, record: &Record, ) -> Result<(), std::io::Error> { let level = match record.level() { Level::Error => "error", Level::Warn => "warn", Level::Info => "info", Level::Debug => "debug", Level::Trace => "trace", }; write!( writer, r#"{{"level":"{}","ts":"{}","logger":"{}","caller":"{}:{}","msg":"{}"}}""#, level, now.now().format("%Y-%m-%dT%H:%M:%S%.3f%:z"), record.module_path().unwrap_or("<unnamed>"), record.file().unwrap_or("<unnamed>"), record.line().unwrap_or(0), &record.args() ) } /// Logs with color, contains the same information as the [pretty_env_logger]. /// /// One log entry has this structure: /// /// ```text /// <timestamp> <log-level> <module-name> > <log-message> /// ``` /// /// [pretty_env_logger]: https://crates.io/crates/pretty_env_logger pub fn color_logger_format( writer: &mut dyn std::io::Write, now: &mut DeferredNow, record: &Record, ) -> Result<(), std::io::Error> { let level = record.level(); write!( writer, "{} {} {} > {}", now.now().format("%Y-%m-%dT%H:%M:%S%.3f"), style(level, level), record.module_path().unwrap_or("<unnamed>"), record.args(), ) } /// Logs without color, contains the same information as the [pretty_env_logger]. /// /// One log entry has this structure: /// /// ```text /// <timestamp> <log-level> <module-name> > <log-message> /// ``` /// /// [pretty_env_logger]: https://crates.io/crates/pretty_env_logger pub fn nocolor_logger_format( writer: &mut dyn std::io::Write, now: &mut DeferredNow, record: &Record, ) -> Result<(), std::io::Error> { write!( writer, "{} {} {} > {}", now.now().format("%Y-%m-%dT%H:%M:%S%.3f"), record.level(), record.module_path().unwrap_or("<unnamed>"), record.args(), ) } /// Initializes a new logger. It logs to stderr. /// /// The default format is: /// /// ```text /// <timestamp>\t<log-level>\t<module-name>\t<source-file>:<line-number>\t<log-message> /// ``` /// /// If the environment variable `GOLOG_LOG_FMT=json` is set, then the output is formatted as JSON: /// /// ```json /// { /// "level": "<log-level>", /// "ts":"<timestamp>", /// "logger":"<module-name>", /// "caller":"<source-file>:<line-number>", /// "msg":"<log-message>" /// } /// ``` /// /// # Panics /// /// Panics if a global logger was already set. pub fn init() { flexi_logger::Logger::with_env() .format(log_format()) .start() .expect("Initializing logger failed. Was another logger already initialized?"); } /// initializes a new logger that logs to an already opened [`std::fs::File`]. /// /// If the environment variable `GOLOG_LOG_FMT=json` is set, then the output is formatted as JSON. /// /// # Panics /// /// Panics if a global logger was already set. /// /// [`std::fs::File`]: https://doc.rust-lang.org/std/fs/struct.File.html pub fn init_with_file(file: File) { flexi_logger::Logger::with_env() .log_target(LogTarget::Writer(Box::new(SingleFileWriter::new(file)))) .format(log_format()) .start() .expect("Initializing logger failed. Was another logger already initialized?"); } /// The log format is based on the `GOLOG_LOG_FMT` environment variable. It can be set to `json`. fn log_format() -> FormatFunction { match env::var("GOLOG_LOG_FMT") { Ok(ref format) if format == "json" => go_log_json_format, _ => { if atty::is(atty::Stream::Stderr) { color_logger_format } else { nocolor_logger_format } } } }