remark42/backend/vendor/github.com/go-pkgz/lgr

lgr - simple logger with some extras

install

go get github.com/go-pkgz/lgr

usage

    l := lgr.New(lgr.Debug, lgr.CallerFile) // allow debug and caller file info
    l.Logf("INFO some important message, %v", err)
    l.Logf("DEBUG some less important message, %v", err)

output looks like this:

2018/01/07 13:02:34.000 INFO  {svc/handler.go:101 h.MyFunc1} some important message, can't open file`
2018/01/07 13:02:34.015 DEBUG {svc/handler.go:155 h.MyFunc2} some less important message, file is too small`

Without lgr.Caller* it will drop {caller} part

details

interfaces and default loggers

• lgr package provides a single interface lgr.L with a single method Logf(format string, args ...interface{}). Function wrapper lgr.Func allows to make lgr.L from a function directly.
• Default logger functionality can be used without lgr.New, but just lgr.Printf
• Two predefined loggers available: lgr.NoOp (do-nothing logger) and lgr.Std (passing directly to stdlib log)

options

lgr.New call accepts functional options:

• lgr.Debug - turn debug mode on to allow messages with "DEBUG" level (filtered overwise)
• lgr.CallerFile - adds the caller file info
• lgr.CallerFunc - adds the caller function info
• lgr.CallerPkg - adds the caller package
• lgr.LevelBraces - wraps levels with "[" and "]"
• lgr.Msec - adds milliseconds to timestamp
• lgr.Out(io.Writer) - sets the output writer, default os.Stdout
• lgr.Err(io.Writer) - sets the error writer, default os.Stderr

levels

lgr.Logf recognizes prefixes like "INFO" or "[INFO]" as levels. The full list of supported levels - "DEBUG", "INFO", "WARN", "ERROR", "PANIC" and "FATAL"

• DEBUG will be filtered unless lgr.Debug option defined
• INFO and WARN don't have any special behavior attached
• ERROR sends messages to both out and err writers
• PANIC and FATAL send messages to both out and err writers. In addition sends dump of callers and runtime info to err only, and calls os.Exit(1).

global logger

Users should avoid global logger and pass the concrete logger as a dependency. However, in some cases a global logger may be needed, for example migration from stdlib log to lgr. For such cases log "github.com/go-pkgz/lgr" can be imported instead of log package.

Global logger provides lgr.Printf, lgr.Print and lgr.Fatalf functions. User can customize the logger by calling lgr.Setup(options ...). The instance of this logger can be retrieved with lgr.Default()