The purpose of this package is to perform logging for CNI projects in NPWG. Cni-log provides general logging functionality for Container Network Interfaces (CNI). Messages can be logged to a log file and/or to standard error.
The package can function out of the box as most of its configurations have default values. Just call any of the logging functions to start logging. To further define log settings such as the log file path, the log level, as well as the lumberjack logger object, continue on to the public functions below.
Import cni-log in your go file:
import (
...
"github.com/k8snetworkplumbingwg/cni-log"
...
)Then perform a go mod tidy to download the package.
Please ensure that the log file is properly specified; otherwise, no information will be printed to the console. In the event that the log file is not configured correctly, relevant error messages will be printed to the console.
...
logging.SetLogFile("samplelog.log")
...CNI-log allows users to modify the logging prefix/header. The default prefix is in the following format:
yyyy-mm-ddTHH:MM:SSZ [<log level>] ...
E.g.
2022-10-11T13:09:57Z [info] This is a log message with INFO log level
To change the prefix used by cni-log, you will need to provide the implementation of how the prefix string would be built. To do so you will need to create an object of type Prefixer. Prefixer is an interface with one function:
CreatePrefix(Level) stringImplement the above function with the code that would build the prefix string. In order for CNI-Log to use your custom prefix you will then need to pass in your custom prefix object using the SetPrefixer function.
Below is sample code on how to build a custom prefix:
package main
import (
...
logging "github.com/k8snetworkplumbingwg/cni-log"
...
)
// custom prefix type
type customPrefix struct {
prefixFormat string
timeFormat string
currentFile string
}
func main() {
// cni-log configuration
logging.SetLogFile("samplelog.log")
logging.SetLogLevel(logging.DebugLevel)
logging.SetLogStderr(true)
// Creating the custom prefix object
prefix := &customPrefix{
prefixFormat: "%s | %s | %s | ",
timeFormat: time.RFC850,
currentFile: "main.go",
}
logging.SetPrefixer(prefix) // Tell cni-log to use your custom prefix object
// Log messages
logging.Infof("Info log message")
logging.Warningf("Warning log message")
}
// Implement the CreatePrefix function using your custom prefix object. This function will be called by CNI-Log
// to build the prefix string.
func (p *customPrefix) CreatePrefix(loggingLevel logging.Level) string {
currentTime := time.Now()
return fmt.Sprintf(p.prefixFormat, currentTime.Format(p.timeFormat), p.currentFile, loggingLevel)
}// Level type
type Level intDefines the type that will represent the different log levels
type Prefixer interface {
CreatePrefix(Level) string
}Defines an interface that contains one function: CreatePrefix(Level) string. Implementing this function allows you to build your own custom prefix.
// LogOptions defines the configuration of the lumberjack logger
type LogOptions struct {
MaxAge *int `json:"maxAge,omitempty"`
MaxSize *int `json:"maxSize,omitempty"`
MaxBackups *int `json:"maxBackups,omitempty"`
Compress *bool `json:"compress,omitempty"`
}For further details of each field, see the lumberjack documentation.
To view the default values of each field, go to the "Default values" section
func SetLogLevel(level Level)Sets the log level. The valid log levels are:
| int | string | Level |
|---|---|---|
| 1 | panic | PanicLevel |
| 2 | error | ErrorLevel |
| 3 | warning | WarningLevel |
| 4 | info | InfoLevel |
| 5 | debug | DebugLevel |
The log levels above are in ascending order of verbosity. For example, setting the log level to InfoLevel would mean "panic", "error", warning", and "info" messages will get logged while "debug" will not.
func GetLogLevel() LevelReturns the current log level
func StringToLevel(level string) LevelReturns the Level equivalent of a string. See SetLogLevel for valid levels.
func (l Level) String() stringReturns the string representation of a log level
func SetLogOptions(options *LogOptions)Configures the lumberjack object based on the lumberjack configuration data set in the logOptions object (see logOptions struct above).
func SetLogFile(filename string)Configures where logs will be written to. If an empty filepath is used, disable logging to file. No change will occur if an invalid filepath (e.g. insufficient permissions) or a symbolic link is passed into the function.
func SetLogStderr(enable bool)This function allows you to enable/disable logging to standard error.
NOTE: For logging, a valid log file must be set or logging to stderr must be enabled.
func SetOutput(out io.Writer)Set custom output. Calling this function will discard any previously set LogOptions.
func SetPrefixer(p Prefixer)This function allows you to override the default logging prefix with a custom prefix.
func SetDefaultPrefixer()This function allows you to return to the default logging prefix.
The logger comes with 2 sets of logging functions.
Printf style functions:
// Errorf prints logging if logging level >= error
func Errorf(format string, a ...interface{}) error
// Warningf prints logging if logging level >= warning
func Warningf(format string, a ...interface{})
// Infof prints logging if logging level >= info
func Infof(format string, a ...interface{})
// Debugf prints logging if logging level >= debug
func Debugf(format string, a ...interface{})Structured (crio logging style) functions:
// PanicStructured provides structured logging for log level >= panic.
func PanicStructured(msg string, args ...interface{})
// ErrorStructured provides structured logging for log level >= error.
func ErrorStructured(msg string, args ...interface{}) error
// WarningStructured provides structured logging for log level >= warning.
func WarningStructured(msg string, args ...interface{})
// InfoStructured provides structured logging for log level >= info.
func InfoStructured(msg string, args ...interface{})
// DebugStructured provides structured logging for log level >= debug.
func DebugStructured(msg string, args ...interface{})| Variable | Default Value |
|---|---|
| logLevel | info |
| logToStderr | true |
| Logger.Filename | "" |
| LogOptions.MaxSize | 100 |
| LogOptions.MaxAge | 5 |
| LogOptions.MaxBackups | 5 |
| LogOptions.Compress | true |