go日志库之logrus

无路是在开发、测试、亦或者调试有一好的日志，都会事半功倍。本节我来学习一下 go 语言明星日志库
logrus。相关链接如下所示
github: https://github.com/sirupsen/logrus
pkg： https://pkg.go.dev/logur.dev/adapter/logrus

Logrus 简介

Logrus 是 Go 语言结构化的 logger，与标准库 logger 完全 API 兼容。

它有以下特点：

• 完全兼容标准日志库，拥有七种日志级别：Trace, Debug, Info, Warning, Error, Fatal
  and Panic。
• 可选的日志输出格式，内置了两种日志格式 JSONFormater 和 TextFormatter，还可以自定义日志格式
• Field 机制，通过 Filed 机制进行结构化的日志记录
• 可扩展的 Hook 机制，允许使用者通过 Hook 的方式将日志分发到任意地方，如本地文件系统，logstash，elasticsearch
  或者 mq 等，或者通过 Hook 定义日志内容和格式等
• 线程安全

logrus 的安装

logrus 安装也非常的简单，直接使用go get即可，安装命令如下所示

go get -v -u logur.dev/adapter/logrus

其中

-v 为显示包安装信息

-u 为安装最新版

logrus 的使用

介绍的包的使用，或许可以从几个维度，初始化、基本使用、骚操作及拓展。源于包使用，但不限于包使用

初始化

logrus 相关于初始化的方面，一共有三种方式。基于New()、Logger、不操作

直接使用

直接使用相对来说更便捷，更清亮。也是相对来说性能最高的，但不足也显而易言，那就是不能有更自由的操作了，如设置
log Level、Hook、Format 等等。

logrus.Trace("trace msg")
logrus.Tracef("trace %v", "msg")

logrus.Debug("debug msg")
logrus.Debugf("debug %v", "msg")

logrus.Info("info msg")
logrus.Infof("info %v", "msg")

logrus.Warn("warn msg")
logrus.Warnf("warn %v", "msg")

logrus.Error("error msg")
logrus.Errorf("error %v", "msg")

logrus.Fatal("fatal msg")
logrus.Fatalf("fatal  %v", "msg")

logrus.Panic("panic msg")
logrus.Panicf("panic  %v", "msg")

当然根据默认的规则会忽略掉一些输出信息

使用 New 初始化于定制

相对直接使用，使用 New 初始化，拥有更多的操作空间。

首先声明一个全局变量log，代码如下所示

var log = logrus.New()

常规情况下对于日志的定制主要在以下几个方面

• 日志可见等级
• 日志格式配置
• 执行调用信息
• 日志另存为

日志可见等级

相关源码如下

const (
 // PanicLevel level, highest level of severity. Logs and then calls panic with the
 // message passed to Debug, Info, ...
 PanicLevel Level = iota
 // FatalLevel level. Logs and then calls `logger.Exit(1)`. It will exit even if the
 // logging level is set to Panic.
 FatalLevel
 // ErrorLevel level. Logs. Used for errors that should definitely be noted.
 // Commonly used for hooks to send errors to an error tracking service.
 ErrorLevel
 // WarnLevel level. Non-critical entries that deserve eyes.
 WarnLevel
 // InfoLevel level. General operational entries about what's going on inside the
 // application.
 InfoLevel
 // DebugLevel level. Usually only enabled when debugging. Very verbose logging.
 DebugLevel
 // TraceLevel level. Designates finer-grained informational events than the Debug.
 TraceLevel
)

简而言之，登记越高（数字越大），显示的等级越全。如 6 显示所有的日志，0 只显示Panic

设置可见等级之需要在log.SetLevel()*（log 为var log = logrus.New()而来）*设置整形(6-0)即可。

日志格式化配置

日志格式化主要分为文本格式化、JSON 格式化、自定义格式化或第三方插件格式化

如下

// log.SetFormatter(&logrus.TextFormatter{
//  DisableColors: false,
//  FullTimestamp: true,
// })
type TextFormatter struct {
 // Set to true to bypass checking for a TTY before outputting colors.
 ForceColors bool

 // Force disabling colors.
 DisableColors bool

 // Force quoting of all values
 ForceQuote bool

 // DisableQuote disables quoting for all values.
 // DisableQuote will have a lower priority than ForceQuote.
 // If both of them are set to true, quote will be forced on all values.
 DisableQuote bool

 // Override coloring based on CLICOLOR and CLICOLOR_FORCE. - https://bixense.com/clicolors/
 EnvironmentOverrideColors bool

 // Disable timestamp logging. useful when output is redirected to logging
 // system that already adds timestamps.
 DisableTimestamp bool

 // Enable logging the full timestamp when a TTY is attached instead of just
 // the time passed since beginning of execution.
 FullTimestamp bool

 // TimestampFormat to use for display when a full timestamp is printed.
 // The format to use is the same than for time.Format or time.Parse from the standard
 // library.
 // The standard Library already provides a set of predefined format.
 TimestampFormat string

 // The fields are sorted by default for a consistent output. For applications
 // that log extremely frequently and don't use the JSON formatter this may not
 // be desired.
 DisableSorting bool

 // The keys sorting function, when uninitialized it uses sort.Strings.
 SortingFunc func([]string)

 // Disables the truncation of the level text to 4 characters.
 DisableLevelTruncation bool

 // PadLevelText Adds padding the level text so that all the levels output at the same length
 // PadLevelText is a superset of the DisableLevelTruncation option
 PadLevelText bool

 // QuoteEmptyFields will wrap empty fields in quotes if true
 QuoteEmptyFields bool

 // Whether the logger's out is to a terminal
 isTerminal bool

 // FieldMap allows users to customize the names of keys for default fields.
 // As an example:
 // formatter := &TextFormatter{
 //     FieldMap: FieldMap{
 //         FieldKeyTime:  "@timestamp",
 //         FieldKeyLevel: "@level",
 //         FieldKeyMsg:   "@message"}}
 FieldMap FieldMap

 // CallerPrettyfier can be set by the user to modify the content
 // of the function and file keys in the data when ReportCaller is
 // activated. If any of the returned value is the empty string the
 // corresponding key will be removed from fields.
 CallerPrettyfier func(*runtime.Frame) (function string, file string)

 terminalInitOnce sync.Once

 // The max length of the level text, generated dynamically on init
 levelTextMaxLength int
}

格式 JSON 化

// log.SetFormatter(&logrus.JSONFormatter{})
type JSONFormatter struct {
 // TimestampFormat sets the format used for marshaling timestamps.
 // The format to use is the same than for time.Format or time.Parse from the standard
 // library.
 // The standard Library already provides a set of predefined format.
 TimestampFormat string

 // DisableTimestamp allows disabling automatic timestamps in output
 DisableTimestamp bool

 // DisableHTMLEscape allows disabling html escaping in output
 DisableHTMLEscape bool

 // DataKey allows users to put all the log entry parameters into a nested dictionary at a given key.
 DataKey string

 // FieldMap allows users to customize the names of keys for default fields.
 // As an example:
 // formatter := &JSONFormatter{
 //    FieldMap: FieldMap{
 //    FieldKeyTime:  "@timestamp",
 //    FieldKeyLevel: "@level",
 //    FieldKeyMsg:   "@message",
 //    FieldKeyFunc:  "@caller",
 //    },
 // }
 FieldMap FieldMap

 // CallerPrettyfier can be set by the user to modify the content
 // of the function and file keys in the json data when ReportCaller is
 // activated. If any of the returned value is the empty string the
 // corresponding key will be removed from json fields.
 CallerPrettyfier func(*runtime.Frame) (function string, file string)

 // PrettyPrint will indent all json logs
 PrettyPrint bool
}

https://github.com/sirupsen/logrus#formatters

写入文件夹 SetOutput

O_RDONLY：只读模式(read-only)

O_WRONLY：只写模式(write-only)

O_RDWR：读写模式(read-write)

O_APPEND：追加模式(append)

O_CREATE：文件不存在就创建(create a new file if none exists.)

O_EXCL：与 O_CREATE 一起用，构成一个新建文件的功能，它要求文件必须不存在(used with O_CREATE, file must
not exist)

O_SYNC：同步方式打开，即不使用缓存，直接写入硬盘 O_TRUNC：打开并清空文件

示例代码如下

func init(){
 logDirPath := `log/` + time.Now().Format("2006-01-02")
 logFilePath := filepath.Join(logDirPath, time.Now().Format(`15`))
 os.MkdirAll(logFilePath, 0775)
 file, err := os.OpenFile(logFilePath + `/` + time.Now().Format(`04`) + `.log`, os.O_RDWR|os.O_CREATE|os.O_APPEND, 0644)
 if err != nil {
  log.Error(`open file error`)
 }
 log.SetOutput(file)
}

log.SetReportCaller(): 显示调用关系，开启这个模式会增加性能开销(成本在 20% 到 40% 之间)。

Hook

logrus 通过实现 Hook接口扩展 hook 机制,可以根据需求将日志分发到任意的存储介质, 比如 es, mq
或者监控报警系统,及时获取异常日志。可以说极大的提高了日志系统的可扩展性。

type Hook interface {
  // 定义哪些等级的日志触发 hook 机制
 Levels() []Level
  // hook 触发器的具体执行操作
  // 如果 Fire 执行失败,错误日志会重定向到标准错误流
 Fire(*Entry) error
}

具体 Hook 示列可参考 https://github.com/sirupsen/logrus/blob/master/hooks/syslog/README.md

referer

https://blog.csdn.net/wangzhezhilu001/article/details/95363789

https://blog.csdn.net/sserf/article/details/103388133