weather/internal/web/server.go

package web

import (
	"context"
	"crypto/tls"
	"encoding/json"
	"fmt"
	"go/weather/pkg/logger"
	"net"
	"net/http"
	"os"
	"time"

	"github.com/gorilla/mux"
	"go.elastic.co/apm"
	"go.uber.org/zap"
)

const (
	apiPrefix     = "/api"
	apiRouterName = "api"
)

//WeatherServer http server for weather application
type WeatherServer struct {
	http.Server
	router     *mux.Router
	wlogger    *logger.WeatherLogger
	subRouters map[string]*mux.Router
	version    string
}

//New construct new instance
func New(logger *logger.WeatherLogger, addr ListenAddr, version string) *WeatherServer {
	return &WeatherServer{
		Server: http.Server{
			Addr: addr.String(),
			BaseContext: func(l net.Listener) context.Context {
				// here configure context properties
				dt := apm.DefaultTracer
				tx := dt.StartTransactionOptions("http", "request", apm.TransactionOptions{
					Start: time.Now(),
				})
				defer tx.End()
				return apm.ContextWithTransaction(context.Background(), tx)
			},
			WriteTimeout: 15 * time.Second,
			ReadTimeout:  15 * time.Second,
		},
		router:     mux.NewRouter(),
		wlogger:    logger,
		subRouters: make(map[string]*mux.Router, 1),
		version:    version,
	}
}

//WithHandler register weather handler
func (ws *WeatherServer) WithHandler() *WeatherServer {

	ws.router.HandleFunc("/", func(rw http.ResponseWriter, r *http.Request) {
		rw.Write([]byte("coucou"))
	})

	api := ws.getOrCreateSubRouterByName(apiRouterName, apiPrefix)
	api.HandleFunc("/health", func(rw http.ResponseWriter, r *http.Request) {
		json.NewEncoder(rw).Encode(map[string]interface{}{
			"ok":      true,
			"version": ws.version,
		})
	})

	return ws
}

//WithHTTPLogging add http server request/response logging capability
func (ws *WeatherServer) WithHTTPLogging() *WeatherServer {
	ws.Server.Handler = ws.wlogger.HTTPLogHandler(ws.router)

	api := ws.getOrCreateSubRouterByName(apiRouterName, apiPrefix)
	api.HandleFunc("/log", ws.wlogger.Level.ServeHTTP)
	return ws
}

//WithErrorLogging add http server error logging capability
func (ws *WeatherServer) WithErrorLogging() *WeatherServer {
	stdLogger, err := zap.NewStdLogAt(ws.wlogger.Logger, zap.ErrorLevel)
	ws.handleError(err)
	ws.Server.ErrorLog = stdLogger
	return ws
}

//WithTLSConfigure add cert and key file to server, permit TLS capability
func (ws *WeatherServer) WithTLSConfigure() *WeatherServer {
	currentPath, err := os.Getwd()
	ws.handleError(err)
	certPath := fmt.Sprintf("%s%ccerts%cout%cweather.pem", currentPath, os.PathSeparator, os.PathSeparator, os.PathSeparator)
	keyPath := fmt.Sprintf("%s%ccerts%cout%cweather-key.pem", currentPath, os.PathSeparator, os.PathSeparator, os.PathSeparator)

	cert, err := tls.LoadX509KeyPair(
		certPath,
		keyPath,
	)
	ws.handleError(err)

	ws.Server.TLSConfig = &tls.Config{Certificates: []tls.Certificate{cert}}
	return ws
}

//Serve start http server
func (ws *WeatherServer) Serve() error {
	// Server.Hanlder is nil when we don't use WithHTTPLogging
	if ws.Server.Handler == nil {
		ws.Server.Handler = ws.router
	}

	return ws.Server.ListenAndServeTLS("", "")
}

//getOrCreateSubRouterByName return a router by name or create if it doesn't exist yet
func (ws *WeatherServer) getOrCreateSubRouterByName(name, prefix string) *mux.Router {
	if api := ws.subRouters[name]; api == nil {
		ws.subRouters[name] = ws.router.PathPrefix(prefix).Subrouter()
	}
	return ws.subRouters[name]
}

//handleError generic fatal error
func (ws *WeatherServer) handleError(err error) {
	if err != nil {
		ws.wlogger.Fatal("Server error", zap.Error(err))
	}
}