Reasonable logging facilities for Go

Simple interface with Time-Thread-Condition-Component based output, with automatic colored output if supported.

• Time: ISO 8901 format timestamps in UTC
• Thread: Log source Goroutine identifiers
• Condition: Log level based logging [TRACE, DEBUG, INFO, WARN, ERROR]
• Component: Go module/package name
• Colors: Automatically detects support for ANSI terminal colorization
• Level Filtering: set a global level and/or per module levels
• Configurable Ouput: use the built in JSON output, or make your own

import (
	"sync"

	log "github.com/mrodden/logr"
	"github.com/mrodden/logr/env_logger"
)

func main() {
	env_logger.Init()

	log.Info("Hello Logging")

	log.Debug("Debug message output")

	wg := sync.WaitGroup{}
	wg.Add(1)
	go func() {
		log.Warn("Warning from inside a goroutine")
		wg.Done()
	}()

	log.Infof("Info format: %#v", wg)

	wg.Wait()
}

The default logging implementation is env_logger which can be configured with the GO_LOG environment variable.

Both the global logging level filter and per module declarations can be declared. The format is similar to the Rust env_logger crate.

Some examples:

• GO_LOG=warn - Sets the global filter level to WARN, causing any logs of WARN, ERROR, or lower to be emitted from all modules.
• GO_LOG=warn,github.com/mymodule/myapp=trace - Sets the global level to WARN, and the filter for the github.com/mymodule/myapp to TRACE level
• GO_LOG=warn,main - Sets the global level to WARN, and enables all logging for the main module.