sloggin

README

slog: Gin middleware

Gin middleware to log http requests using slog.

See also:

• slog-multi: workflows of slog handlers (pipeline, fanout, ...)
• slog-formatter: slog attribute formatting
• slog-datadog: A slog handler for Datadog
• slog-logstash: A slog handler for Logstash
• slog-slack: A slog handler for Slack
• slog-loki: A slog handler for Loki
• slog-sentry: A slog handler for Sentry
• slog-fluentd: A slog handler for Fluentd
• slog-syslog: A slog handler for Syslog
• slog-graylog: A slog handler for Graylog

🚀 Install

go get github.com/samber/slog-gin

Compatibility: go >= 1.20.1

This library is v0 and follows SemVer strictly. On slog final release (go 1.21), this library will go v1.

No breaking changes will be made to exported APIs before v1.0.0.

💡 Usage

Minimal

import (
	"net/http"
	"os"
	"time"

	"github.com/gin-gonic/gin"
	sloggin "github.com/samber/slog-gin"
	"golang.org/x/exp/slog"
)

// Create a slog logger, which:
//   - Logs to stdout.
logger := slog.New(slog.NewTextHandler(os.Stdout))

router := gin.New()

// Add the sloggin middleware to all routes.
// The middleware will log all requests attributes.
router.Use(sloggin.New(logger))

// Example pong request.
router.GET("/pong", func(c *gin.Context) {
    c.String(http.StatusOK, "pong")
})

router.Run(":1234")

// output:
// time=2023-04-10T14:00:0.000000+02:00 level=INFO msg="HTTP Request" status=200 method=GET path=/pong ip=127.0.0.1 latency=25.5µs user-agent=curl/7.77.0 time=2023-04-10T14:00:00.000+02:00

Using custom time formatters

import (
	"net/http"
	"os"
	"time"

	"github.com/gin-gonic/gin"
	sloggin "github.com/samber/slog-gin"
	"golang.org/x/exp/slog"
)

// Create a slog logger, which:
//   - Logs to stdout.
//   - RFC3339 with UTC time format.
logger := slog.New(
    slogformatter.NewFormatterHandler(
        slogformatter.TimezoneConverter(time.UTC),
        slogformatter.TimeFormatter(time.DateTime, nil),
    )(
        slog.NewTextHandler(os.Stdout),
    ),
)

router := gin.New()

// Add the sloggin middleware to all routes.
// The middleware will log all requests attributes.
router.Use(sloggin.New(logger))

// Example pong request.
router.GET("/pong", func(c *gin.Context) {
    c.String(http.StatusOK, "pong")
})

router.Run(":1234")

// output:
// time="2023-04-10 14:00:00" level=INFO msg="HTTP Request" status=200 method=GET path=/pong ip=127.0.0.1 latency=25.5µs user-agent=curl/7.77.0 time="2023-04-10 14:00:00"

Using custom logger sub-group

import (
	"net/http"
	"os"
	"time"

	"github.com/gin-gonic/gin"
	sloggin "github.com/samber/slog-gin"
	"golang.org/x/exp/slog"
)

// Create a slog logger, which:
//   - Logs to stdout.
logger := slog.New(slog.NewTextHandler(os.Stdout))

router := gin.New()

// Add the sloggin middleware to all routes.
// The middleware will log all requests attributes under a "http" group.
router.Use(sloggin.New(logger.WithGroup("http")))

// Example pong request.
router.GET("/pong", func(c *gin.Context) {
    c.String(http.StatusOK, "pong")
})

router.Run(":1234")

// output:
// time=2023-04-10T14:00:0.000000+02:00 level=INFO msg="HTTP Request" http.status=200 http.method=GET http.path=/pong http.ip=127.0.0.1 http.latency=20.125µs http.user-agent=curl/7.77.0 time=2023-04-10T14:00:00.000+02:00

Add logger to a single route

import (
	"net/http"
	"os"
	"time"

	"github.com/gin-gonic/gin"
	sloggin "github.com/samber/slog-gin"
	"golang.org/x/exp/slog"
)

// Create a slog logger, which:
//   - Logs to stdout.
logger := slog.New(slog.NewTextHandler(os.Stdout))

router := gin.New()

// Example pong request.
// Add the sloggin middleware to a single routes.
router.GET("/pong", sloggin.New(logger), func(c *gin.Context) {
    c.String(http.StatusOK, "pong")
})

router.Run(":1234")

// output:
// time="2023-04-10 14:00:00" level=INFO msg="HTTP Request" status=200 method=GET path=/pong ip=127.0.0.1 latency=25.5µs user-agent=curl/7.77.0 time="2023-04-10 14:00:00"

Adding custom attributes

import (
	"net/http"
	"os"
	"time"

	"github.com/gin-gonic/gin"
	sloggin "github.com/samber/slog-gin"
	"golang.org/x/exp/slog"
)

// Create a slog logger, which:
//   - Logs to stdout.
logger := slog.New(slog.NewTextHandler(os.Stdout)).
    With("environment", "production").
    With("server", "gin/1.9.0").
    With("server_start_time", time.Now()).
    With("gin_mode", gin.EnvGinMode)

router := gin.New()

// Add the sloggin middleware to all routes.
// The middleware will log all requests attributes.
router.Use(sloggin.New(logger))

// Example pong request.
router.GET("/pong", func(c *gin.Context) {
    c.String(http.StatusOK, "pong")
})

router.Run(":1234")

// output:
// time=2023-04-10T14:00:0.000000+02:00 level=INFO msg="HTTP Request" environment=production server=gin/1.9.0 gin_mode=release server_start_time=2023-04-10T10:00:00.000+02:00 status=200 method=GET path=/pong ip=127.0.0.1 latency=25.5µs user-agent=curl/7.77.0 time=2023-04-10T14:00:00.000+02:00

JSON output

import (
	"net/http"
	"os"
	"time"

	"github.com/gin-gonic/gin"
	sloggin "github.com/samber/slog-gin"
	"golang.org/x/exp/slog"
)

// Create a slog logger, which:
//   - Logs to stdout.
logger := slog.New(slog.NewJSONHandler(os.Stdout))

router := gin.New()

// Add the sloggin middleware to all routes.
// The middleware will log all requests attributes.
router.Use(sloggin.New(logger))

// Example pong request.
router.GET("/pong", func(c *gin.Context) {
    c.String(http.StatusOK, "pong")
})

router.Run(":1234")

// output:
// {"time":"2023-04-10T14:00:0.000000+02:00","level":"INFO","msg":"HTTP Request","gin_mode":"GIN_MODE","status":200,"method":"GET","path":"/pong","ip":"127.0.0.1","latency":15542,"user-agent":"curl/7.77.0","time":"2023-04-10T14:00:0.000000+02:00"}

🤝 Contributing

• Ping me on twitter @samuelberthe (DMs, mentions, whatever :))
• Fork the project
• Fix open issues or request new features

Don't hesitate ;)

# Install some dev dependencies
make tools

# Run tests
make test
# or
make watch-test

👤 Contributors

💫 Show your support

Give a ⭐️ if this project helped you!

📝 License

Copyright © 2023 Samuel Berthe.

This project is MIT licensed.

Documentation

Index

• func New(logger *slog.Logger) gin.HandlerFunc
• func NewWithConfig(logger *slog.Logger, config Config) gin.HandlerFunc
• type Config

Functions

func New

func New(logger *slog.Logger) gin.HandlerFunc

New returns a gin.HandlerFunc (middleware) that logs requests using slog.

Requests with errors are logged using slog.Error(). Requests without errors are logged using slog.Info().

func NewWithConfig

func NewWithConfig(logger *slog.Logger, config Config) gin.HandlerFunc

Types

type Config

type Config struct {
	DefaultLevel     slog.Level
	ClientErrorLevel slog.Level
	ServerErrorLevel slog.Level
}