This package provides a wrapper around the underlying logging library that allows to log messages of different severity levels with additional fields.

The package exports four logging functions for each severity level: Debug(), Info(), Warn(), and Error(). Each function takes a message string and zero or more fields of type Field, which can be used to provide additional context to the log message.

The package also provides a Sync() function that flushes any buffered log entries. Applications should take care to call Sync() before exiting.

The package exports four interfaces, InfoLogger, WarnLogger, DebugLogger, and ErrorLogger, each providing a method to log messages with the corresponding severity level. The package also exports a Logger interface that encompasses all the severity levels and the Sync() method.

The package exports the following log level constants:

• LevelInfo: info severity level
• LevelWarn: warn severity level
• LevelDebug: debug severity level
• LevelError: error severity level

The Field type that is used to pass additional values to the log functions. The package provides a Any() function that creates a new Field that associates a key with an arbitrary value. It takes a string key and an interface{} value, and returns a Field.

The package initializes the logger during package initialization by calling the New() function. The function reads the LOG_LEVEL environment variable and sets the log level accordingly. The default log level is info. The logger also reports the line number of the calling function.

This example logs the message "Hello, world!" with the additional context foo=bar at the info severity level.

package main

import "my-package/submodules/log"

func main() {
  log.Info("Hello, world!", log.Any("foo", "bar"))
  log.Error(errors.New("Hello world!"), log.Tip("Bark!"))
}