webhooker/internal/server/server.go

package server

import (
	"context"
	"fmt"
	"log/slog"
	"net/http"
	"os"
	"os/signal"
	"syscall"
	"time"

	"go.uber.org/fx"
	"sneak.berlin/go/webhooker/internal/config"
	"sneak.berlin/go/webhooker/internal/globals"
	"sneak.berlin/go/webhooker/internal/handlers"
	"sneak.berlin/go/webhooker/internal/logger"
	"sneak.berlin/go/webhooker/internal/middleware"

	"github.com/getsentry/sentry-go"
	"github.com/go-chi/chi"

	// spooky action at a distance!
	// this populates the environment
	// from a ./.env file automatically
	// for development configuration.
	// .env contents should be things like
	// `DBURL=postgres://user:pass@.../`
	// (without the backticks, of course)
	_ "github.com/joho/godotenv/autoload"
)

// ServerParams is a standard fx naming convention for dependency injection
// nolint:golint
type ServerParams struct {
	fx.In
	Logger     *logger.Logger
	Globals    *globals.Globals
	Config     *config.Config
	Middleware *middleware.Middleware
	Handlers   *handlers.Handlers
}

type Server struct {
	startupTime   time.Time
	exitCode      int
	sentryEnabled bool
	log           *slog.Logger
	ctx           context.Context
	cancelFunc    context.CancelFunc
	httpServer    *http.Server
	router        *chi.Mux
	params        ServerParams
	mw            *middleware.Middleware
	h             *handlers.Handlers
}

func New(lc fx.Lifecycle, params ServerParams) (*Server, error) {
	s := new(Server)
	s.params = params
	s.mw = params.Middleware
	s.h = params.Handlers
	s.log = params.Logger.Get()

	lc.Append(fx.Hook{
		OnStart: func(ctx context.Context) error {
			s.startupTime = time.Now()
			go s.Run()
			return nil
		},
		OnStop: func(ctx context.Context) error {
			s.cleanShutdown()
			return nil
		},
	})
	return s, nil
}

func (s *Server) Run() {
	s.configure()

	// logging before sentry, because sentry logs
	s.enableSentry()

	s.serve()
}

func (s *Server) enableSentry() {
	s.sentryEnabled = false

	if s.params.Config.SentryDSN == "" {
		return
	}

	err := sentry.Init(sentry.ClientOptions{
		Dsn:     s.params.Config.SentryDSN,
		Release: fmt.Sprintf("%s-%s", s.params.Globals.Appname, s.params.Globals.Version),
	})
	if err != nil {
		s.log.Error("sentry init failure", "error", err)
		// Don't use fatal since we still want the service to run
		return
	}
	s.log.Info("sentry error reporting activated")
	s.sentryEnabled = true
}

func (s *Server) serve() int {
	s.ctx, s.cancelFunc = context.WithCancel(context.Background())

	// signal watcher
	go func() {
		c := make(chan os.Signal, 1)
		signal.Ignore(syscall.SIGPIPE)
		signal.Notify(c, os.Interrupt, syscall.SIGTERM)
		// block and wait for signal
		sig := <-c
		s.log.Info("signal received", "signal", sig.String())
		if s.cancelFunc != nil {
			// cancelling the main context will trigger a clean
			// shutdown.
			s.cancelFunc()
		}
	}()

	go s.serveUntilShutdown()

	<-s.ctx.Done()
	s.cleanShutdown()
	return s.exitCode
}

func (s *Server) cleanupForExit() {
	s.log.Info("cleaning up")
	// TODO: close database connections, flush buffers, etc.
}

func (s *Server) cleanShutdown() {
	// initiate clean shutdown
	s.exitCode = 0
	ctxShutdown, shutdownCancel := context.WithTimeout(context.Background(), 5*time.Second)
	defer shutdownCancel()

	if err := s.httpServer.Shutdown(ctxShutdown); err != nil {
		s.log.Error("server clean shutdown failed", "error", err)
	}

	s.cleanupForExit()

	if s.sentryEnabled {
		sentry.Flush(2 * time.Second)
	}
}

func (s *Server) MaintenanceMode() bool {
	return s.params.Config.MaintenanceMode
}

func (s *Server) configure() {
	// identify ourselves in the logs
	s.params.Logger.Identify()
}