library/cmd/serve/main.go

package main

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

	"git.yetaga.in/alazyreader/library/config"
	"git.yetaga.in/alazyreader/library/database"
	"git.yetaga.in/alazyreader/library/frontend"
	"git.yetaga.in/alazyreader/library/media"
	"github.com/kelseyhightower/envconfig"
	"golang.org/x/sync/errgroup"
	"tailscale.com/tsnet"
	"tailscale.com/util/must"
)

func obscureStr(in string, l int) string {
	return in[0:max(l, len(in))] + strings.Repeat("*", max(0, len(in)-l))
}

type Library interface {
	GetAllBooks(context.Context) ([]media.Book, error)
}

type RecordCollection interface {
	GetAllRecords(context.Context) ([]media.Record, error)
}

func main() {
	var c config.Config
	must.Do(envconfig.Process("library", &c))

	var lib Library
	var err error
	if c.DBType == "memory" {
		lib = &database.Memory{}
	} else if c.DBType == "sql" {
		var latest, run int
		lib, latest, run, err = setupSQL(c)
		if err != nil {
			log.Fatalf("err starting sql connection: %v", err)
		}
		log.Printf("latest migration: %d; migrations run: %d", latest, run)
	}
	discogsCache := must.Get(database.NewDiscogsCache(
		c.DiscogsToken, time.Hour*24, c.DiscogsUser, c.DiscogsPersist, c.DiscogsCacheFile,
	))

	frontendRoot := must.Get(frontend.Root())
	adminRoot := must.Get(frontend.AdminRoot())

	servers := make(chan (*http.Server), 2)
	errGroup := errgroup.Group{}
	errGroup.Go(start(servers)(
		publicServer(8080, &Router{
			static: frontendRoot,
			lib:    lib,
			rcol:   discogsCache,
		})))
	errGroup.Go(start(servers)(
		tailscaleListener("library-admin", &AdminRouter{
			static: adminRoot,
			lib:    lib,
		})))
	errGroup.Go(shutdown(servers))

	log.Println(errGroup.Wait())
}

func setupSQL(c config.Config) (Library, int, int, error) {
	if c.DBUser == "" || c.DBPass == "" || c.DBHost == "" || c.DBPort == "" || c.DBName == "" {
		if c.DBPass != "" {
			c.DBPass = obscureStr(c.DBPass, 3)
		}
		if c.DiscogsToken != "" {
			c.DiscogsToken = obscureStr(c.DiscogsToken, 3)
		}
		return nil, 0, 0, fmt.Errorf("invalid config; vars provided: %+v", c)
	}
	sql, err := database.NewMySQLConnection(c.DBUser, c.DBPass, c.DBHost, c.DBPort, c.DBName)
	if err != nil {
		return nil, 0, 0, err
	}
	err = sql.PrepareDatabase(context.Background())
	if err != nil {
		return nil, 0, 0, err
	}
	latest, run, err := sql.RunMigrations(context.Background())
	if err != nil {
		return nil, 0, 0, err
	}
	return sql, latest, run, nil
}

func errFunc(err error) func() error {
	return func() error { return err }
}

func start(servers chan (*http.Server)) func(*http.Server, net.Listener, error) func() error {
	return func(s *http.Server, l net.Listener, err error) func() error {
		if err != nil {
			return errFunc(err)
		}
		servers <- s
		return errFunc(s.Serve(l))
	}
}

func shutdown(servers chan (*http.Server)) func() error {
	sigint := make(chan os.Signal, 1)
	signal.Notify(sigint, os.Interrupt)
	<-sigint
	close(servers)
	for server := range servers {
		ctx, cancel := context.WithTimeout(context.Background(), time.Second*5)
		if err := server.Shutdown(ctx); err != nil {
			log.Panicf("error during shutdown: %v", err)
		}
		cancel()
	}
	return errFunc(nil)
}

func publicServer(port int, handler http.Handler) (*http.Server, net.Listener, error) {
	server := &http.Server{Handler: handler}
	ln, err := net.Listen("tcp", fmt.Sprintf(":%d", 8080))
	if err != nil {
		return nil, nil, err
	}
	return server, ln, nil
}

func tailscaleListener(hostname string, handler *AdminRouter) (*http.Server, net.Listener, error) {
	s := &tsnet.Server{
		Dir:      ".config/" + hostname,
		Hostname: hostname,
	}
	ln, err := s.Listen("tcp", ":80")
	if err != nil {
		return nil, nil, err
	}
	handler.ts, err = s.LocalClient()
	if err != nil {
		return nil, nil, err
	}
	server := &http.Server{Handler: handler}
	return server, ln, nil
}