learn-go/snippetbox/cmd/web/main.go

package main

import (
	"crypto/tls"
	"database/sql"
	"flag"
	"html/template"
	"log/slog"
	"net/http"
	"regexp"
	"os"
	"time"

	"snippetbox.chaosfem.tw/internal/models"

	"github.com/alexedwards/scs/mysqlstore"
	"github.com/alexedwards/scs/v2"
	"github.com/go-playground/form/v4"
	_ "github.com/go-sql-driver/mysql"
)

// for application wide dependencies
type application struct {
	logger *slog.Logger
	snippets *models.SnippetModel
	users *models.UserModel
	templateCache map[string]*template.Template
	formDecoder *form.Decoder
	sessionManager *scs.SessionManager
}

// main it's the snippetbox webapp
func main() {
	// configuration
	addr := flag.String("addr", ":4000", "HTTP network address")
	dsn := flag.String("dsn", "web:dbpass@/snippetbox?parseTime=true", "DB data source name")
	logfmt := flag.String("logfmt", "text", "Log output format")
	loglevel := flag.String("loglevel", "INFO", "Log level: DEBUG, INFO, WARN, or ERROR")
	flag.Parse()

	logger := loggerBuilder(logfmt, loglevel)

	db, err := openDB(*dsn, logger)
	if err != nil {
		logger.Error(err.Error())
		os.Exit(1)
	}

	defer db.Close()

	templateCache, err := newTemplateCache()
	if err != nil {
		logger.Error(err.Error())
		os.Exit(1)
	}

	formDecoder := form.NewDecoder()

	sessionManager := scs.New()
	sessionManager.Store = mysqlstore.New(db)
	sessionManager.Lifetime = 12 * time.Hour

	// setup the application
	app := &application{
		logger: logger,
		snippets: &models.SnippetModel{DB: db},
		users: &models.UserModel{DB: db},
		templateCache: templateCache,
		formDecoder: formDecoder,
		sessionManager: sessionManager,
	}

	tlsConfig := &tls.Config{
		CurvePreferences: []tls.CurveID{tls.X25519, tls.CurveP256},
	}

	srv := &http.Server{
		Addr:         *addr,
		Handler:      app.routes(),
		ErrorLog:     slog.NewLogLogger(logger.Handler(), slog.LevelError),
		TLSConfig:    tlsConfig,
		IdleTimeout:  time.Minute,
		ReadTimeout:  5 * time.Second,
		WriteTimeout: 10 * time.Second,
	}

	logger.Info("starting server", slog.String("addr", srv.Addr))

	err = srv.ListenAndServeTLS("./tls/cert.pem", "./tls/key.pem")

	logger.Error(err.Error())
	os.Exit(1)
}

func openDB(dsn string, logger *slog.Logger) (*sql.DB, error) {
	db, err := sql.Open("mysql", dsn)
	if err != nil {
		return nil, err
	}

	err = db.Ping()
	if err != nil {
		db.Close()
		return nil, err
	}
	passRegexp := regexp.MustCompile(":\\S+@")
	logger.Info("Opened DB connection pool", slog.String("adapter", "mysql"), slog.String("dsn", passRegexp.ReplaceAllString(dsn, ":<REDACTED>@")))

	return db, nil
}