sloggin

slog: Gin middleware

Changes compared to source repo.

slog-gin.NewWithConfig() now takes reference to config. so we can update the config on the runtime. this gets utilized at the webserver so we can put changes at the runtime and print the request/response body which helps in debug purpose.

Gin middleware to log http requests using slog.

See also:

• slog-multi: slog.Handler chaining, fanout, routing, failover, load balancing...
• slog-formatter: slog attribute formatting
• slog-sampling: slog sampling policy
• slog-gin: Gin middleware for slog logger
• slog-echo: Echo middleware for slog logger
• slog-fiber: Fiber middleware for slog logger
• slog-chi: Chi middleware for slog logger
• slog-datadog: A slog handler for Datadog
• slog-rollbar: A slog handler for Rollbar
• slog-sentry: A slog handler for Sentry
• slog-syslog: A slog handler for Syslog
• slog-logstash: A slog handler for Logstash
• slog-fluentd: A slog handler for Fluentd
• slog-graylog: A slog handler for Graylog
• slog-loki: A slog handler for Loki
• slog-slack: A slog handler for Slack
• slog-telegram: A slog handler for Telegram
• slog-mattermost: A slog handler for Mattermost
• slog-microsoft-teams: A slog handler for Microsoft Teams
• slog-webhook: A slog handler for Webhook
• slog-kafka: A slog handler for Kafka
• slog-nats: A slog handler for NATS
• slog-parquet: A slog handler for Parquet + Object Storage
• slog-zap: A slog handler for Zap
• slog-zerolog: A slog handler for Zerolog
• slog-logrus: A slog handler for Logrus
• slog-channel: A slog handler for Go channels

🚀 Install

go get github.com/samber/slog-gin

Compatibility: go >= 1.21

No breaking changes will be made to exported APIs before v2.0.0.

💡 Usage

Minimal

import (
	"github.com/gin-gonic/gin"
	sloggin "github.com/samber/slog-gin"
	"log/slog"
)

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

router := gin.New()

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

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

router.Run(":1234")

// output:
// time=2023-10-15T20:32:58.926+02:00 level=INFO msg="Incoming request" env=production request.time=2023-10-15T20:32:58.626+02:00 request.method=GET request.path=/ request.query="" request.route="" request.ip=127.0.0.1:63932 request.length=0 response.time=2023-10-15T20:32:58.926+02:00 response.latency=100ms response.status=200 response.length=7 id=""

OTEL

logger := slog.New(slog.NewTextHandler(os.Stdout, nil))

config := sloggin.Config{
	WithSpanID:  true,
	WithTraceID: true,
}

router := gin.New()
router.Use(sloggin.NewWithConfig(logger, config))

Custom log levels

logger := slog.New(slog.NewTextHandler(os.Stdout, nil))

config := sloggin.Config{
	DefaultLevel:     slog.LevelInfo,
	ClientErrorLevel: slog.LevelWarn,
	ServerErrorLevel: slog.LevelError,
}

router := gin.New()
router.Use(sloggin.NewWithConfig(logger, config))

Verbose

logger := slog.New(slog.NewTextHandler(os.Stdout, nil))

config := sloggin.Config{
	WithRequestBody: true,
	WithResponseBody: true,
	WithRequestHeader: true,
	WithResponseHeader: true,
}

router := gin.New()
router.Use(sloggin.NewWithConfig(logger, config))

Filters

logger := slog.New(slog.NewTextHandler(os.Stdout, nil))

router := gin.New()
router.Use(
	sloggin.NewWithFilters(
		logger,
		sloggin.Accept(func (c *gin.Context) bool {
			return xxx
		}),
		sloggin.IgnoreStatus(401, 404),
	),
)

Available filters:

• Accept / Ignore
• AcceptMethod / IgnoreMethod
• AcceptStatus / IgnoreStatus
• AcceptStatusGreaterThan / IgnoreStatusLessThan
• AcceptStatusGreaterThanOrEqual / IgnoreStatusLessThanOrEqual
• AcceptPath / IgnorePath
• AcceptPathContains / IgnorePathContains
• AcceptPathPrefix / IgnorePathPrefix
• AcceptPathSuffix / IgnorePathSuffix
• AcceptPathMatch / IgnorePathMatch
• AcceptHost / IgnoreHost
• AcceptHostContains / IgnoreHostContains
• AcceptHostPrefix / IgnoreHostPrefix
• AcceptHostSuffix / IgnoreHostSuffix
• AcceptHostMatch / IgnoreHostMatch

Using custom time formatters

import (
	"github.com/gin-gonic/gin"
	sloggin "github.com/samber/slog-gin"
	slogformatter "github.com/samber/slog-formatter"
	"log/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, nil),
    ),
)

router := gin.New()

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

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

router.Run(":1234")

// output:
// time=2023-10-15T20:32:58.926+02:00 level=INFO msg="Incoming request" env=production request.time=2023-10-15T20:32:58Z request.method=GET request.path=/ request.query="" request.route="" request.ip=127.0.0.1:63932 request.length=0 response.time=2023-10-15T20:32:58Z response.latency=100ms response.status=200 response.length=7 id=""

Using custom logger sub-group

logger := slog.New(slog.NewTextHandler(os.Stdout, nil))

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")))
router.Use(gin.Recovery())

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

router.Run(":1234")

// output:
// time=2023-10-15T20:32:58.926+02:00 level=INFO msg="Incoming request" env=production http.request.time=2023-10-15T20:32:58.626+02:00 http.request.method=GET http.request.path=/ request.query="" http.request.route="" http.request.ip=127.0.0.1:63932 http.request.length=0 http.response.time=2023-10-15T20:32:58.926+02:00 http.response.latency=100ms http.response.status=200 http.response.length=7 http.id=""

Add logger to a single route

logger := slog.New(slog.NewTextHandler(os.Stdout, nil))

router := gin.New()
router.Use(gin.Recovery())

// 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")

Adding custom attributes

logger := slog.New(slog.NewTextHandler(os.Stdout, nil)).
    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))
router.Use(gin.Recovery())

// Example pong request.
router.GET("/pong", func(c *gin.Context) {
	// Add an attribute to a single log entry.
	sloggin.AddCustomAttributes(c, slog.String("foo", "bar"))
    c.String(http.StatusOK, "pong")
})

router.Run(":1234")

// output:
// time=2023-10-15T20:32:58.926+02:00 level=INFO msg="Incoming request" environment=production server=gin/1.9.0 gin_mode=release request.time=2023-10-15T20:32:58.626+02:00 request.method=GET request.path=/ request.query="" request.route="" request.ip=127.0.0.1:63932 request.length=0 response.time=2023-10-15T20:32:58.926+02:00 response.latency=100ms response.status=200 response.length=7 id="" foo=bar

JSON output

logger := slog.New(slog.NewJSONHandler(os.Stdout, nil))

router := gin.New()

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

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

router.Run(":1234")

// output:
// {"time":"2023-10-15T20:32:58.926+02:00","level":"INFO","msg":"Incoming request","gin_mode":"GIN_MODE","env":"production","http":{"request":{"time":"2023-10-15T20:32:58.626+02:00","method":"GET","path":"/","query":"","route":"","ip":"127.0.0.1:55296","length":0},"response":{"time":"2023-10-15T20:32:58.926+02:00","latency":100000,"status":200,"length":7},"id":""}}

🤝 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.