logger

README

Logger configuration

snet-daemon uses logrus log library. Logger configuration is a set of properties started from log. prefix. If configuration file is formatted using JSON then all logger configuration is one JSON object located in log field.

• log - log configuration section

  • level (default: info) - log level. Possible values are logrus log levels

    • debug
    • info
    • warn
    • error
    • fatal
    • panic

  • timezone (default: UTC) - timezone to format timestamps and log file names. It should be name of the time.Location, see time.LoadLocation.

  • formatter - set of properties with log.formatter. prefix describes logger formatter configuration.

    • type (default: json) - type of the log formatter. Two types are supported, which correspond to logrus formatter types, see logrus Formatter

      • json
      • text

    • timestamp_format (default: "2006-01-02T15:04:05.999999999Z07:00") - timestamp format to use in log lines, standard time.Time formats are supported, see time.Time.Format

  • output - set of properties with log.output. prefix describes logger output configuration.

    • type (default: file) - type of the logger output. Two types are supported:

      • file - file-rotatelogs output which supports log rotation
      • stdout - os.Stdout

    • file_pattern (default: ./snet-daemon.%Y%m%d.log) - log file name which may include date/time patterns in strftime (3) format. Time and date in file name are necessary to support log rotation.

    • current_link (default: ./snet-daemon.log) - link to the latest log file.

    • rotation_time_in_sec (default: 86400 (1 day)) - number of seconds before log rotation happens.

    • max_age_in_sec (default: 604800 (1 week)) - number of seconds since last modification time before log file is removed.

    • rotation_count (default: 0 (disabled)) - max number of rotation files. When number of log files becomes greater then oldest log file is removed.

  • hooks (default: []) - list of names of the hooks which will be executed when message with specified log level appears in log. See logrus hooks. List contains names of the hooks and hook configuration can be found by name prefix. Thus for hook named <hook-name> properties will start from log.<hook-name>. prefix.

  • <hook-name> - configuration of log hook with <hook-name> name

    • type (required) - Type of the hook. this type is used to find actual hook implementation. Hook types supported:

      • mail_auth - logrus_mail

    • levels (required) - list of log levels to trigger the hook.

    • config (depends on hook implementation) - set of properties with log.<hook-name>.config prefix are passed to the hook implementation when it is initialized. This list of properties is hook specific.

logrus_mail hook config

Its configuration should contain all of the properties which are required to call NewMailAuthHook method

• application_name
• host
• port
• from
• to
• username
• password

Resulting log configuration using logrus_mail hook:

  "log": {
    ...
    "hooks": [ "send-mail" ],
    "send-mail": {
      "type": "mail_auth",
      "levels": ["Error", "Warn"],
      "config": {
		"application_name": "test-application-name",
		"host": "smtp.gmail.com",
		"port": 587,
		"from": "from-user@gmail.com",
		"to": "to-user@gmail.com",
		"username": "smtp-username",
		"password": "secret"
	  }
    },
  }

Default logger configuration in JSON format

  "log": {
    "formatter": {
      "timestamp_format": "2006-01-02T15:04:05.999999999Z07:00",
      "type": "text"
    },
    "hooks": [],
    "level": "info",
    "output": {
      "current_link": "./snet-daemon.log",
      "file_pattern": "./snet-daemon.%Y%m%d.log",
      "max_age_in_sec": 604800,
      "rotation_count": 0,
      "rotation_time_in_sec": 86400,
      "type": "file"
    },
    "timezone": "UTC"
  }

Adding new hooks implementations

Adding new hook implementation is trivial. You should implement factory method which inputs hook configuration as Viper config and returns new instance of the Hook structure. Then register new hook type by calling RegisterHookType() function from init() method.

Please see "mail_auth" hook implementation as example:

• factory method implementation
• registering new hook type

Documentation

Index

• Constants
• func InitLogger(config *viper.Viper) error
• func RegisterHookType(hookType string, hookFactoryMethod func(*viper.Viper) (*Hook, error))
• type Hook

Constants

const (
	LogHookTypeKey   = "type"
	LogHookLevelsKey = "levels"
	LogHookConfigKey = "config"

	LogHookMailApplicationNameKey = "application_name"
	LogHookMailHostKey            = "host"
	LogHookMailPortKey            = "port"
	LogHookMailFromKey            = "from"
	LogHookMailToKey              = "to"
	LogHookMailUsernameKey        = "username"
	LogHookMailPasswordKey        = "password"
)

const (
	LogLevelKey     = "level"
	LogTimezoneKey  = "timezone"
	LogFormatterKey = "formatter"
	LogOutputKey    = "output"
	LogHooksKey     = "hooks"

	LogFormatterTypeKey         = "type"
	LogFormatterTimezoneKey     = "timezone"
	LogFormatterTimestampFormat = "timestamp_format"

	LogOutputTypeKey                  = "type"
	LogOutputFileFilePatternKey       = "file_pattern"
	LogOutputFileCurrentLinkKey       = "current_link"
	LogOutputFileClockTimezoneKey     = "clock_timezone"
	LogOutputFileRotationTimeInSecKey = "rotation_time_in_sec"
	LogOutputFileMaxAgeInSecKey       = "max_age_in_sec"
	LogOutputFileRotationCountKey     = "rotation_count"
)

Logger configuration keys

Functions

func InitLogger

func InitLogger(config *viper.Viper) error

InitLogger initializes logger using configuration provided by viper instance.

Function designed to configure few different loggers with different formatter and output settings. To achieve this viper configuration contains separate sections for each logger, each output and each formatter.

func RegisterHookType

func RegisterHookType(hookType string, hookFactoryMethod func(*viper.Viper) (*Hook, error))

RegisterHookType registers new hook type in the system.

Types

type Hook

type Hook struct {
	// Delegate keeps logrus hook pointer to call on message.
	Delegate log.Hook
	// ExitHandler is a function to be called before terminating application
	// when logrus.Fatal() method was called.
	ExitHandler func()
}

Hook is a structure to return new log message hooks instances from factory method.