httplog - HTTP Request Logger

A small but powerful structured logging package for HTTP request logging, built on the Go 1.21+ standard library slog package.

Features

• Efficient Logging: Separates frontend (slog.Logger) and backend (slog.Handler) to optimize performance in serving HTTP responses quickly.
• Extensible Backend: The provided backend slog.Handler is both extensible and replaceable, allowing customization to suit your logging needs.
• Flexible Attribute Attachment: Supports attaching additional log attributes from within downstream HTTP handlers or middlewares, ensuring comprehensive and contextual logging.
• Debug Request and Response Bodies: Provides options to log request and response bodies for debugging and analysis.
• Panic Recovery: Optionally recovers from panics in underlying HTTP handlers or middlewares, logging the error and ensuring a consistent response status code.

Example

See _example/main.go. Try running it locally:

$ cd _example

# JSON logger
$ ENV=production go run .

# pretty logger
$ ENV=localhost go run .

Usage

go get github.com/golang-cz/httplog@latest

package main

import (
	"errors"
	"fmt"
	"log"
	"log/slog"
	"net/http"
	"os"

	"github.com/go-chi/chi/v5"
	"github.com/go-chi/chi/v5/middleware"
	"github.com/golang-cz/httplog"
)

func main() {
	logger := slog.New(slog.NewJSONHandler(os.Stdout, nil)).With(
		slog.String("app", "example-app"),
		slog.String("version", "v1.0.0-a1fa420"),
		slog.String("env", "production"),
	)

	r := chi.NewRouter()

	// Request logger
	r.Use(httplog.RequestLogger(logger, &httplog.Options{
		// Level defines the verbosity of the request logs:
		// slog.LevelDebug - log both request starts & responses (incl. OPTIONS)
		// slog.LevelInfo  - log all responses (excl. OPTIONS)
		// slog.LevelWarn  - log 4xx and 5xx responses only (except for 429)
		// slog.LevelError - log 5xx responses only
		Level: slog.LevelInfo,

		// Concise mode causes fewer log attributes to be printed in request logs.
		// This is useful if your console is too noisy during development.
		Concise: false,

		// RecoverPanics recovers from panics occurring in the underlying HTTP handlers
		// and middlewares. It returns HTTP 500 unless response status was already set.
		//
		// NOTE: Panics are logged as errors automatically, regardless of this setting.
		RecoverPanics: true,

		// Select request/response headers to be logged explicitly.
		LogRequestHeaders:  []string{"User-Agent", "Origin", "Referer"},
		LogResponseHeaders: []string{},

		// You can log request/request body. Useful for debugging.
		LogRequestBody:  false,
		LogResponseBody: false,
	}))

	r.Get("/", func(w http.ResponseWriter, r *http.Request) {
		ctx := r.Context()

		// Set attribute on the request log.
		httplog.SetAttrs(ctx, slog.String("userId", "id"))

		w.Write([]byte("."))
	})

	http.ListenAndServe("localhost:8000", r)
}

TODO

• Integrate panic recoverer
• Debug request body
• Debug response body
• Add example
• Add tests

License

MIT license