github.com/neatio-project/log15

log15

Package log15 provides an opinionated, simple toolkit for best-practice logging in Go (golang) that is both human and machine readable. It is modeled after the Go standard library's io and net/http packages and is an alternative to the standard library's log package.

Features

• A simple, easy-to-understand API
• Promotes structured logging by encouraging use of key/value pairs
• Child loggers which inherit and add their own private context
• Lazy evaluation of expensive operations
• Simple Handler interface allowing for construction of flexible, custom logging configurations with a tiny API.
• Color terminal support
• Built-in support for logging to files, streams, syslog, and the network
• Support for forking records to multiple handlers, buffering records for output, failing over from failed handler writes, + more

Versioning

The API of the master branch of log15 should always be considered unstable. If you want to rely on a stable API, you must vendor the library.

Importing

import log "github.com/inconshreveable/log15"

Examples

// all loggers can have key/value context
srvlog := log.New("module", "app/server")

// all log messages can have key/value context 
srvlog.Warn("abnormal conn rate", "rate", curRate, "low", lowRate, "high", highRate)

// child loggers with inherited context
connlog := srvlog.New("raddr", c.RemoteAddr())
connlog.Info("connection open")

// lazy evaluation
connlog.Debug("ping remote", "latency", log.Lazy{pingRemote})

// flexible configuration
srvlog.SetHandler(log.MultiHandler(
    log.StreamHandler(os.Stderr, log.LogfmtFormat()),
    log.LvlFilterHandler(
        log.LvlError,
        log.Must.FileHandler("errors.json", log.JsonFormat())))

Breaking API Changes

The following commits broke API stability. This reference is intended to help you understand the consequences of updating to a newer version of log15.

• 57a084d014d4150152b19e4e531399a7145d1540 - Added a Get() method to the Logger interface to retrieve the current handler
• 93404652ee366648fa622b64d1e2b67d75a3094a - Record field Call changed to stack.Call with switch to github.com/go-stack/stack
• a5e7613673c73281f58e15a87d2cf0cf111e8152 - Restored syslog.Priority argument to the SyslogXxx handler constructors

FAQ

The varargs style is brittle and error prone! Can I have type safety please?

Yes. Use log.Ctx:

srvlog := log.New(log.Ctx{"module": "app/server"})
srvlog.Warn("abnormal conn rate", log.Ctx{"rate": curRate, "low": lowRate, "high": highRate})

License

Apache