✨ Created LogFmt middleware

internal/middleware/logfmt.go

@@ -0,0 +1,128 @@
+package middleware
+
+import (
+	"io"
+	"net/http"
+	"os"
+	"strings"
+	"sync/atomic"
+	"time"
+
+	"github.com/go-logfmt/logfmt"
+)
+
+type (
+	LogFmtConfig struct {
+		// Skipper defines a function to skip middleware.
+		Skipper Skipper
+
+		// Output is a writer where logs in JSON format are written.
+		// Optional. Default value os.Stdout.
+		Output io.Writer
+
+		// TODO(toby3d): allow select some tags
+	}
+
+	logFmtResponse struct {
+		http.ResponseWriter
+		error          error
+		start          time.Time
+		statusCode     int
+		responseLength int
+		id             uint64
+	}
+)
+
+//nolint:gochecknoglobals // default configuration
+var DefaultLogFmtConfig = LogFmtConfig{
+	Skipper: DefaultSkipper,
+	Output:  os.Stdout,
+}
+
+//nolint:gochecknoglobals
+var globalConnID uint64
+
+func LogFmt() Interceptor {
+	c := DefaultLogFmtConfig
+
+	return LogFmtWithConfig(c)
+}
+
+func LogFmtWithConfig(config LogFmtConfig) Interceptor {
+	if config.Skipper == nil {
+		config.Skipper = DefaultLogFmtConfig.Skipper
+	}
+
+	if config.Output == nil {
+		config.Output = DefaultLogFmtConfig.Output
+	}
+
+	encoder := logfmt.NewEncoder(config.Output)
+
+	return func(w http.ResponseWriter, r *http.Request, next http.HandlerFunc) {
+		rw := &logFmtResponse{
+			id:             nextConnID(),
+			responseLength: 0,
+			ResponseWriter: w,
+			start:          time.Now().UTC(),
+			statusCode:     0,
+		}
+
+		next(rw, r)
+
+		end := time.Now().UTC()
+
+		encoder.EncodeKeyvals(
+			"bytes_in", r.ContentLength,
+			"bytes_out", rw.responseLength,
+			"error", rw.error,
+			"host", r.Host,
+			"id", rw.id,
+			"latency", end.Sub(rw.start).Nanoseconds(),
+			"latency_human", end.Sub(rw.start).String(),
+			"method", r.Method,
+			"path", r.URL.Path,
+			"protocol", r.Proto,
+			"referer", r.Referer(),
+			"remote_ip", r.RemoteAddr,
+			"status", rw.statusCode,
+			"time_rfc3339", rw.start.Format(time.RFC3339),
+			"time_rfc3339_nano", rw.start.Format(time.RFC3339Nano),
+			"time_unix", rw.start.Unix(),
+			"time_unix_nano", rw.start.UnixNano(),
+			"uri", r.RequestURI,
+			"user_agent", r.UserAgent(),
+		)
+
+		for name, src := range map[string]map[string][]string{
+			"form":   r.PostForm,
+			"header": r.Header,
+			"query":  r.URL.Query(),
+		} {
+			for k, v := range src {
+				encoder.EncodeKeyval(name+"_"+strings.ReplaceAll(strings.ToLower(k), "-", "_"), v)
+			}
+		}
+
+		encoder.EndRecord()
+	}
+}
+
+func (r *logFmtResponse) WriteHeader(status int) {
+	r.statusCode = status
+
+	r.ResponseWriter.WriteHeader(status)
+}
+
+func (r *logFmtResponse) Write(src []byte) (int, error) {
+	var l int
+
+	l, r.error = r.ResponseWriter.Write(src)
+	r.responseLength += l
+
+	return l, r.error
+}
+
+func nextConnID() uint64 {
+	return atomic.AddUint64(&globalConnID, 1)
+}