directory/internal/middleware/middleware.go

package middleware

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

	basicauth "github.com/99designs/basicauth-go"
	"github.com/go-chi/chi/middleware"
	"github.com/go-chi/cors"
	"github.com/rs/zerolog"
	"sneak.berlin/go/directory/internal/config"
	"sneak.berlin/go/directory/internal/globals"
	"sneak.berlin/go/directory/internal/logger"

	metrics "github.com/slok/go-http-metrics/metrics/prometheus"
	ghmm "github.com/slok/go-http-metrics/middleware"
	"github.com/slok/go-http-metrics/middleware/std"
	"github.com/spf13/viper"
	"go.uber.org/fx"
)

type MiddlewareParams struct {
	fx.In
	Logger  *logger.Logger
	Globals *globals.Globals
	Config  *config.Config
}

type Middleware struct {
	log    *zerolog.Logger
	params *MiddlewareParams
}

func New(lc fx.Lifecycle, params MiddlewareParams) (*Middleware, error) {
	s := new(Middleware)
	s.params = &params
	s.log = params.Logger.Get()
	return s, nil
}

// the following is from
// https://learning-cloud-native-go.github.io/docs/a6.adding_zerolog_logger/

func ipFromHostPort(hp string) string {
	h, _, err := net.SplitHostPort(hp)
	if err != nil {
		return ""
	}
	if len(h) > 0 && h[0] == '[' {
		return h[1 : len(h)-1]
	}
	return h
}

type loggingResponseWriter struct {
	http.ResponseWriter
	statusCode int
}

func NewLoggingResponseWriter(w http.ResponseWriter) *loggingResponseWriter {
	return &loggingResponseWriter{w, http.StatusOK}
}

func (lrw *loggingResponseWriter) WriteHeader(code int) {
	lrw.statusCode = code
	lrw.ResponseWriter.WriteHeader(code)
}

// type Middleware func(http.Handler) http.Handler
// this returns a Middleware that is designed to do every request through the
// mux, note the signature:
func (s *Middleware) Logging() func(http.Handler) http.Handler {
	// FIXME this should use https://github.com/google/go-cloud/blob/master/server/requestlog/requestlog.go
	return func(next http.Handler) http.Handler {
		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
			start := time.Now()
			lrw := NewLoggingResponseWriter(w)
			ctx := r.Context()
			defer func() {
				latency := time.Since(start)
				s.log.Info().
					Time("request_start", start).
					Str("method", r.Method).
					Str("url", r.URL.String()).
					Str("useragent", r.UserAgent()).
					Str("request_id", ctx.Value(middleware.RequestIDKey).(string)).
					Str("referer", r.Referer()).
					Str("proto", r.Proto).
					Str("remoteIP", ipFromHostPort(r.RemoteAddr)).
					Int("status", lrw.statusCode).
					Int("latency_ms", int(latency.Milliseconds())).
					Send()
			}()

			next.ServeHTTP(lrw, r)
		})
	}
}

func (s *Middleware) CORS() func(http.Handler) http.Handler {
	return cors.Handler(cors.Options{
		// CHANGEME! these are defaults, change them to suit your needs or
		// read from environment/viper.
		// AllowedOrigins: []string{"https://foo.com"}, // Use this to allow specific origin hosts
		AllowedOrigins: []string{"*"},
		// AllowOriginFunc:  func(r *http.Request, origin string) bool { return true },
		AllowedMethods:   []string{"GET", "POST", "PUT", "DELETE", "OPTIONS"},
		AllowedHeaders:   []string{"Accept", "Authorization", "Content-Type", "X-CSRF-Token"},
		ExposedHeaders:   []string{"Link"},
		AllowCredentials: false,
		MaxAge:           300, // Maximum value not ignored by any of major browsers
	})
}

func (s *Middleware) Metrics() func(http.Handler) http.Handler {
	mdlw := ghmm.New(ghmm.Config{
		Recorder: metrics.NewRecorder(metrics.Config{}),
	})
	return func(next http.Handler) http.Handler {
		return std.Handler("", mdlw, next)
	}
}

func (s *Middleware) MetricsAuth() func(http.Handler) http.Handler {
	return basicauth.New(
		"metrics",
		map[string][]string{
			viper.GetString("METRICS_USERNAME"): {
				viper.GetString("METRICS_PASSWORD"),
			},
		},
	)
}