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slog: Echo middleware

tag Go Version GoDoc Build Status Go report Coverage Contributors License

Echo middleware to log http requests using slog.

See also:

HTTP middlewares:

Loggers:

Log sinks:

πŸš€ Install

# echo v4 (current)
go get github.com/samber/slog-echo

# echo v5 (alpha)
go get github.com/samber/slog-echo@echo-v5

Compatibility: go >= 1.21

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

πŸ’‘ Usage

Handler options

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

	WithUserAgent      bool
	WithRequestID      bool
	WithRequestBody    bool
	WithRequestHeader  bool
	WithResponseBody   bool
	WithResponseHeader bool
	WithSpanID         bool
	WithTraceID        bool

	Filters []Filter
}

Attributes will be injected in log payload.

Other global parameters:

slogecho.TraceIDKey = "trace_id"
slogecho.SpanIDKey = "span_id"
slogecho.RequestBodyMaxSize  = 64 * 1024 // 64KB
slogecho.ResponseBodyMaxSize = 64 * 1024 // 64KB
slogecho.HiddenRequestHeaders = map[string]struct{}{ ... }
slogecho.HiddenResponseHeaders = map[string]struct{}{ ... }

Minimal

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

	"github.com/labstack/echo/v4"
	"github.com/labstack/echo/v4/middleware"
	slogecho "github.com/samber/slog-echo"
	"log/slog"
)

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

// Echo instance
e := echo.New()

// Middleware
e.Use(slogecho.New(logger))
e.Use(middleware.Recover())

// Routes
e.GET("/", func(c echo.Context) error {
	return c.String(http.StatusOK, "Hello, World!")
})
e.GET("/error", func(c echo.Context) error {
	return echo.
		NewHTTPError(http.StatusInternalServerError, "I'm angry").
		WithInternal(errors.New("I'm angry internally"))
})

// Start server
e.Logger.Fatal(e.Start(":4242"))

// output:
// time=2023-10-15T20:32:58.926+02:00 level=INFO msg="Success" env=production request.time=2023-10-15T20:32:58.626+02:00 request.method=GET request.path=/ 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=229c7fc8-64f5-4467-bc4a-940700503b0d  http.error="map[code:500 internal:I'm angry internally message:I'm angry]" http.internal="I'm angry internally"

OTEL

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

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

e := echo.New()
e.Use(slogecho.NewWithConfig(logger, config))
e.Use(middleware.Recover())

Custom log levels

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

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

e := echo.New()
e.Use(slogecho.NewWithConfig(logger, config))
e.Use(middleware.Recover())

Verbose

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

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

e := echo.New()
e.Use(slogecho.NewWithConfig(logger, config))
e.Use(middleware.Recover())

Filters

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

e := echo.New()
e.Use(
	slogecho.NewWithFilters(
		logger,
		slogecho.Accept(func (c echo.Context) bool {
			return xxx
		}),
		slogecho.IgnoreStatus(401, 404),
	),
)
e.Use(middleware.Recover())

Available filters:

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 / IgnoreStatusGreaterThan
  • AcceptStatusLessThan / IgnoreStatusLessThan
  • AcceptStatusGreaterThanOrEqual / IgnoreStatusGreaterThanOrEqual
  • AcceptStatusLessThanOrEqual / 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/labstack/echo/v4"
	"github.com/labstack/echo/v4/middleware"
	slogecho "github.com/samber/slog-echo"
	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),
	),
)

// Echo instance
e := echo.New()

// Middleware
e.Use(slogecho.New(logger))
e.Use(middleware.Recover())

// Routes
e.GET("/", func(c echo.Context) error {
	return c.String(http.StatusOK, "Hello, World!")
})
e.GET("/error", func(c echo.Context) error {
	return echo.
		NewHTTPError(http.StatusInternalServerError, "I'm angry").
		WithInternal(errors.New("I'm angry internally"))
})

// Start server
e.Logger.Fatal(e.Start(":4242"))

// output:
// time=2023-10-15T20:32:58.926+02:00 level=INFO msg="Success" env=production request.time=2023-10-15T20:32:58Z request.method=GET request.path=/ 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=229c7fc8-64f5-4467-bc4a-940700503b0d error="map[code:500 internal:I'm angry internally message:I'm angry]" internal="I'm angry internally"

Using custom logger sub-group

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

// Echo instance
e := echo.New()

// Middleware
e.Use(slogecho.New(logger.WithGroup("http")))
e.Use(middleware.Recover())

// Routes
e.GET("/", func(c echo.Context) error {
	return c.String(http.StatusOK, "Hello, World!")
})
e.GET("/error", func(c echo.Context) error {
	return echo.
		NewHTTPError(http.StatusInternalServerError, "I'm angry").
		WithInternal(errors.New("I'm angry internally"))
})

// Start server
e.Logger.Fatal(e.Start(":4242"))

// output:
// time=2023-10-15T20:32:58.926+02:00 level=INFO msg="Success" env=production http.request.time=2023-10-15T20:32:58.626+02:00 http.request.method=GET http.request.path=/ 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=229c7fc8-64f5-4467-bc4a-940700503b0d http.error="map[code:500 internal:I'm angry internally message:I'm angry]" http.internal="I'm angry internally"

Add logger to a single route

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

// Echo instance
e := echo.New()

// Middleware
e.Use(middleware.Recover())

// Routes
e.GET("/", func(c echo.Context) error {
	return c.String(http.StatusOK, "Hello, World!")
}, slogecho.New(logger))

// Start server
e.Logger.Fatal(e.Start(":4242"))

Adding custom attributes

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

// Add an attribute to all log entries made through this logger.
logger = logger.With("env", "production")

// Echo instance
e := echo.New()

// Middleware
e.Use(slogecho.New(logger))
e.Use(middleware.Recover())

// Routes
e.GET("/", func(c echo.Context) error {
	// Add an attribute to a single log entry.
	slogecho.AddCustomAttributes(c, slog.String("foo", "bar"))
	return c.String(http.StatusOK, "Hello, World!")
})

// Start server
e.Logger.Fatal(e.Start(":4242"))

// output:
// time=2023-10-15T20:32:58.926+02:00 level=INFO msg="Success" env=production request.time=2023-10-15T20:32:58.626+02:00 request.method=GET request.path=/ 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=229c7fc8-64f5-4467-bc4a-940700503b0d foo=bar error="map[code:500 internal:I'm angry internally message:I'm angry]" internal="I'm angry internally"

JSON output

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

// Echo instance
e := echo.New()

// Middleware
e.Use(slogecho.New(logger))
e.Use(middleware.Recover())

// Routes
e.GET("/", func(c echo.Context) error {
	return c.String(http.StatusOK, "Hello, World!")
})

// Start server
e.Logger.Fatal(e.Start(":4242"))

// output:
// {"time":"2023-10-15T20:32:58.926+02:00","level":"INFO","msg":"Success","env":"production","http":{"request":{"time":"2023-10-15T20:32:58.626+02:00","method":"GET","path":"/","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":"04201917-d7ba-4b20-a3bb-2fffba5f2bd9"}, "error": {"code":500, "internal":"I'm angry internally", "message":"I'm angry"}, "internal": "I'm angry internally"}

🀝 Contributing

Don't hesitate ;)

# Install some dev dependencies
make tools

# Run tests
make test
# or
make watch-test

πŸ‘€ Contributors

Contributors

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πŸ“ License

Copyright Β© 2023 Samuel Berthe.

This project is MIT licensed.