Customization

The logger has several options youc an use to further customize it's output in your code:

package main

import (
    "os"
    log "github.com/bdlm/log"
)

func init() {
    // Blacklist a string from appearing in the log. The characters in any
    // substring match to a word that has been added will be replaced with
    // asterisks (*).
    log.AddSecret("some-secret-text")

    // Register a function that will execute prior to the os.Exit call when a
    // fatal error is logged.
    log.RegisterExitHandler(func() {
        // gracefully shutdown something...
    })

    // Log as JSON instead of the default ASCII formatter.
    log.SetFormatter(&log.TextFormatter{
        // Set various formatter options:
        //   DisableCaller:    true,
        //   DisableHostname:  true,
        //   DisableLevel:     true,
        //   DisableMessage:   true,
        //   DisableTimestamp: true,
        //   DisableTTY:       true,
        //   EnableTrace:      true,
        //   EscapeHTML:       true,
        //   ForceTTY:         true,
        //   FieldMap:         FieldMap{LabelMsg: "message"},
        //   TimestampFormat:  2006",
    })

    // Output to stdout instead of the default stderr. Can be any io.Writer, see
    // below for a File example.
    log.SetOutput(os.Stdout)

    // Only log the warning severity or above.
    log.SetLevel(log.WarnLevel)
}

func main() {
    log.WithFields(log.Fields{
        "animal": "walrus",
        "size":   10,
    }).Info("A group of walrus emerges from the ocean")

    log.WithFields(log.Fields{
        "omg":    true,
        "number": 122,
    }).Warn("The group's number increased tremendously!")

    log.WithFields(log.Fields{
        "omg":    true,
        "number": 100,
    }).Fatal("The ice breaks!")

    // A common pattern is to re-use fields between logging statements by re-using
    // the log.Entry returned from WithFields()
    contextLogger := log.WithFields(log.Fields{
        "common": "this is a common field",
        "other": "I also should be logged always",
    })

    contextLogger.Info("I'll be logged with common and other field")
    contextLogger.Info("Me too")
}