Logger

Logger middleware for Fiber that logs HTTP request/response details.

Signatures

func New(config ...Config) fiber.Handler

Examples

Import the middleware package that is part of the Fiber web framework

import (
    "github.com/gofiber/fiber/v2"
    "github.com/gofiber/fiber/v2/middleware/logger"
)

tip

The order of registration plays a role. Only all routes that are registered after this one will be logged. The middleware should therefore be one of the first to be registered.

After you initiate your Fiber app, you can use the following possibilities:

// Initialize default config
app.Use(logger.New())

// Or extend your config for customization
// Logging remote IP and Port
app.Use(logger.New(logger.Config{
    Format: "[${ip}]:${port} ${status} - ${method} ${path}\n",
}))

// Logging Request ID
app.Use(requestid.New())
app.Use(logger.New(logger.Config{
    // For more options, see the Config section
    Format: "${pid} ${locals:requestid} ${status} - ${method} ${path}​\n",
}))

// Changing TimeZone & TimeFormat
app.Use(logger.New(logger.Config{
    Format:     "${pid} ${status} - ${method} ${path}\n",
    TimeFormat: "02-Jan-2006",
    TimeZone:   "America/New_York",
}))

// Custom File Writer
file, err := os.OpenFile("./123.log", os.O_RDWR|os.O_CREATE|os.O_APPEND, 0666)
if err != nil {
    log.Fatalf("error opening file: %v", err)
}
defer file.Close()
app.Use(logger.New(logger.Config{
    Output: file,
}))

// Add Custom Tags
app.Use(logger.New(logger.Config{
    CustomTags: map[string]logger.LogFunc{
        "custom_tag": func(output logger.Buffer, c *fiber.Ctx, data *logger.Data, extraParam string) (int, error) {
            return output.WriteString("it is a custom tag")
        },
    },
}))

// Callback after log is written
app.Use(logger.New(logger.Config{
    TimeFormat: time.RFC3339Nano,
    TimeZone:   "Asia/Shanghai",
    Done: func(c *fiber.Ctx, logString []byte) {
        if c.Response().StatusCode() != fiber.StatusOK {
            reporter.SendToSlack(logString) 
        }
    },
}))

Config

// Config defines the config for middleware.
type Config struct {
    // Next defines a function to skip this middleware when returned true.
    //
    // Optional. Default: nil
    Next func(c *fiber.Ctx) bool

    // Done is a function that is called after the log string for a request is written to Output,
    // and pass the log string as parameter.
    //
    // Optional. Default: nil
    Done func(c *fiber.Ctx, logString []byte)

    // tagFunctions defines the custom tag action
    //
    // Optional. Default: map[string]LogFunc
    CustomTags map[string]LogFunc

    // Format defines the logging tags
    //
    // Optional. Default: [${time}] ${status} - ${latency} ${method} ${path}\n
    Format string

    // TimeFormat https://programming.guide/go/format-parse-string-time-date-example.html
    //
    // Optional. Default: 15:04:05
    TimeFormat string

    // TimeZone can be specified, such as "UTC" and "America/New_York" and "Asia/Chongqing", etc
    //
    // Optional. Default: "Local"
    TimeZone string

    // TimeInterval is the delay before the timestamp is updated
    //
    // Optional. Default: 500 * time.Millisecond
    TimeInterval time.Duration

    // Output is a writer where logs are written
    //
    // Default: os.Stdout
    Output io.Writer

    enableColors     bool
    enableLatency    bool
    timeZoneLocation *time.Location
}
type LogFunc func(buf logger.Buffer, c *fiber.Ctx, data *logger.Data, extraParam string) (int, error)

Default Config

var ConfigDefault = Config{
    Next:         nil,
    Done:         nil,
    Format:       "[${time}] ${status} - ${latency} ${method} ${path}\n",
    TimeFormat:   "15:04:05",
    TimeZone:     "Local",
    TimeInterval: 500 * time.Millisecond,
    Output:       os.Stdout,
    enableColors: true,
}

Constants

// Logger variables
const (
    TagPid               = "pid"
    TagTime              = "time"
    TagReferer           = "referer"
    TagProtocol          = "protocol"
    TagPort              = "port"
    TagIP                = "ip"
    TagIPs               = "ips"
    TagHost              = "host"
    TagMethod            = "method"
    TagPath              = "path"
    TagURL               = "url"
    TagUA                = "ua"
    TagLatency           = "latency"
    TagStatus            = "status"         // response status
    TagResBody           = "resBody"        // response body
    TagReqHeaders        = "reqHeaders"
    TagQueryStringParams = "queryParams"    // request query parameters
    TagBody              = "body"           // request body
    TagBytesSent         = "bytesSent"
    TagBytesReceived     = "bytesReceived"
    TagRoute             = "route"
    TagError             = "error"
    // DEPRECATED: Use TagReqHeader instead
    TagHeader            = "header:"        // request header
    TagReqHeader         = "reqHeader:"     // request header
    TagRespHeader        = "respHeader:"    // response header
    TagQuery             = "query:"         // request query
    TagForm              = "form:"          // request form
    TagCookie            = "cookie:"        // request cookie
    TagLocals            = "locals:"
    // colors
    TagBlack             = "black"
    TagRed               = "red"
    TagGreen             = "green"
    TagYellow            = "yellow"
    TagBlue              = "blue"
    TagMagenta           = "magenta"
    TagCyan              = "cyan"
    TagWhite             = "white"
    TagReset             = "reset"
)