go-logger

Yet another Go logger library.

Version 2

The new version of this library implements some breaking changes:

• The initialization options contains some changes. Once the logger is initialized, the rest of the code should be compatible with the v1 version.
• Added per-target logging level. Now you can optionally specify a different logging level for console and file logging. For example, you can just send limited logs to a third-party provider to avoid high costs and keep a detailed local file log for debugging purposes.
• timestamp and level fields are always added to a JSON log. DO NOT include them when the input is a struct.
• Verbosity level for the default logger is now Info instead of Warning.

How to use

1. Import the library

import (
    logger "github.com/randlabs/go-logger/v2"
)

2. Then use logger.Create to create a logger object with desired options.
3. Optionally, you can also use the default logger which outputs only to console by accessing logger.Default().

Logger options:

The Options struct accepts several modifiers that affects the logger behavior:

Field	Meaning
Console	Establishes some options for the console output.
File	Enable file logging. Optional. Details below.
SysLog	Enable SysLog logging. Optional. Details below.
Level	Set the initial logging level to use.
DebugLevel	Set the initial logging level for debug output to use.
UseLocalTime	Use the local computer time instead of UTC.
ErrorHandler	A callback to call if an internal error is encountered.

ConsoleOptions:

Field	Meaning
Disable	Disabled console output.
Level	Optional logging level to use in the console output.
DebugLevel	Optional logging level for debug output to use in the console output.

FileOptions:

Field	Meaning
Prefix	Filename prefix to use when a file is created. Defaults to the binary name.
Directory	Destination directory to store log files.
DaysToKeep	Amount of days to keep old logs.
Level	Optional logging level to use in the file output.
DebugLevel	Optional logging level for debug output to use in the file output.

SysLogOptions:

Field	Meaning
AppName	Application name to use. Defaults to the binary name.
Host	Syslog server host name.
Port	Syslog server port. Defaults to 514, 1468 or 6514 depending on the network protocol used.
UseTcp	Use TCP instead of UDP.
UseTls	Uses a secure connection. Implies TCP.
UseRFC5424	Send messages in the new RFC 5424 format instead of the original RFC 3164 specification.
MaxMessageQueueSize	Set the maximum amount of messages to keep in memory if connection to the server is lost.
TlsConfig	An optional pointer to a tls.Config object to provide the TLS configuration for use.
Level	Optional logging level to use in the syslog output.
DebugLevel	Optional logging level for debug output to use in the syslog output.

Example

package example

import (
    "fmt"

    logger "github.com/randlabs/go-logger/v2"
)

// Define a custom JSON message. Timestamp and level will be automatically added by the logger.
type JsonMessage struct {
    Message string `json:"message"`
}

func main() {
    // Create the logger
    lg, err := logger.Create(logger.Options{
        File: &logger.FileOptions{
            Directory:  "./logs",
            DaysToKeep: 7,
        },
        Level:        logger.LogLevelDebug,
        DebugLevel:   1,
    })
    if err != nil {
        // Use default logger to send the error
        logger.Default().Error(fmt.Sprintf("unable to initialize. [%v]", err))
        return
    }
    // Defer logger shut down
    defer lg.Destroy()

    // Send some logs using the plain text format 
    lg.Error("This is an error message sample")
    lg.Warning("This is a warning message sample")
    lg.Info("This is an information message sample")
    lg.Debug(1, "This is a debug message sample at level 1 which should be printed")
    lg.Debug(2, "This is a debug message sample at level 2 which should NOT be printed")

    // Send some other logs using the JSON format 
    lg.Error(JsonMessage{
        Message: "This is an error message sample",
    })
    lg.Warning(JsonMessage{
        Message: "This is a warning message sample",
    })
    lg.Info(JsonMessage{
        Message: "This is an information message sample",
    })
    lg.Debug(1, JsonMessage{
        Message: "This is a debug message sample at level 1 which should be printed",
    })
    lg.Debug(2, JsonMessage{
        Message: "This is a debug message sample at level 2 which should NOT be printed",
    })
}

License

See LICENSE file for details.