main.go

// Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
// or more contributor license agreements. Licensed under the Elastic License;
// you may not use this file except in compliance with the Elastic License.

package main

import (
	"context"
	"crypto/tls"
	"flag"
	"fmt"
	"log"
	"net/http"
	_ "net/http/pprof"
	"os"
	"os/signal"
	"strings"
	"syscall"
	"time"

	gstorage "cloud.google.com/go/storage"
	"github.com/gorilla/mux"

	"github.com/prometheus/client_golang/prometheus"
	"github.com/prometheus/client_golang/prometheus/promhttp"
	"go.elastic.co/apm/module/apmgorilla/v2"
	"go.elastic.co/apm/v2"
	"go.uber.org/zap"
	"go.uber.org/zap/zapcore"

	ucfgYAML "github.com/elastic/go-ucfg/yaml"

	"github.com/elastic/package-registry/internal/util"
	"github.com/elastic/package-registry/metrics"
	"github.com/elastic/package-registry/packages"
	"github.com/elastic/package-registry/proxymode"
	"github.com/elastic/package-registry/storage"
)

const (
	serviceName         = "package-registry"
	version             = "1.26.1"
	defaultInstanceName = "localhost"
)

var (
	address         string
	httpProfAddress string
	metricsAddress  string

	logLevel *zapcore.Level
	logType  string

	tlsCertFile string
	tlsKeyFile  string

	tlsMinVersionValue tlsVersionValue

	dryRun     bool
	configPath string

	printVersionInfo bool

	featureStorageIndexer        bool
	storageIndexerBucketInternal string
	storageEndpoint              string
	storageIndexerWatchInterval  time.Duration

	featureProxyMode bool
	proxyTo          string

	defaultConfig = Config{
		CacheTimeIndex:      10 * time.Second,
		CacheTimeSearch:     10 * time.Minute,
		CacheTimeCategories: 10 * time.Minute,
		CacheTimeCatchAll:   10 * time.Minute,
	}
)

func init() {
	flag.BoolVar(&printVersionInfo, "version", false, "Print Elastic Package Registry version")
	flag.StringVar(&address, "address", "localhost:8080", "Address of the package-registry service.")
	flag.StringVar(&metricsAddress, "metrics-address", "", "Address to expose the Prometheus metrics (experimental). ")

	logLevel = zap.LevelFlag("log-level", zap.InfoLevel, "log level (default \"info\")")
	flag.StringVar(&logType, "log-type", util.DefaultLoggerType, "log type (ecs, dev)")
	flag.StringVar(&tlsCertFile, "tls-cert", "", "Path of the TLS certificate.")
	flag.StringVar(&tlsKeyFile, "tls-key", "", "Path of the TLS key.")
	flag.Var(&tlsMinVersionValue, "tls-min-version", "Minimum version TLS supported.")
	flag.StringVar(&configPath, "config", "config.yml", "Path to the configuration file.")
	flag.StringVar(&httpProfAddress, "httpprof", "", "Enable HTTP profiler listening on the given address.")
	// This flag is experimental and might be removed in the future or renamed
	flag.BoolVar(&dryRun, "dry-run", false, "Runs a dry-run of the registry without starting the web service (experimental).")
	flag.BoolVar(&packages.ValidationDisabled, "disable-package-validation", false, "Disable package content validation.")
	// The following storage related flags are technical preview and might be removed in the future or renamed
	flag.BoolVar(&featureStorageIndexer, "feature-storage-indexer", false, "Enable storage indexer to include packages from Package Storage v2 (technical preview).")
	flag.StringVar(&storageIndexerBucketInternal, "storage-indexer-bucket-internal", "", "Path to the internal Package Storage bucket (with gs:// prefix).")
	flag.StringVar(&storageEndpoint, "storage-endpoint", "https://package-storage.elastic.co/", "Package Storage public endpoint.")
	flag.DurationVar(&storageIndexerWatchInterval, "storage-indexer-watch-interval", 1*time.Minute, "Address of the package-registry service.")

	// The following proxy-indexer related flags are technical preview and might be removed in the future or renamed
	flag.BoolVar(&featureProxyMode, "feature-proxy-mode", false, "Enable proxy mode to include packages from other endpoint (technical preview).")
	flag.StringVar(&proxyTo, "proxy-to", "https://epr.elastic.co/", "Proxy-to endpoint")
}

type Config struct {
	PackagePaths        []string      `config:"package_paths"`
	CacheTimeIndex      time.Duration `config:"cache_time.index"`
	CacheTimeSearch     time.Duration `config:"cache_time.search"`
	CacheTimeCategories time.Duration `config:"cache_time.categories"`
	CacheTimeCatchAll   time.Duration `config:"cache_time.catch_all"`
}

func main() {
	err := parseFlags()
	if err != nil {
		log.Fatal(err)
	}

	if tlsMinVersionValue > 0 {
		if tlsCertFile == "" || tlsKeyFile == "" {
			log.Fatalf("-tls-min-version set but missing TLS cert and key files (-tls-cert and -tls-key)")
		}
	}

	if printVersionInfo {
		fmt.Printf("Elastic Package Registry version %v\n", version)
		os.Exit(0)
	}

	apmTracer := initAPMTracer()
	defer apmTracer.Close()

	logger, err := util.NewLogger(util.LoggerOptions{
		APMTracer: apmTracer,
		Level:     logLevel,
		Type:      logType,
	})
	if err != nil {
		log.Fatalf("Failed to initialize logging: %v", err)
	}
	defer logger.Sync()

	apmTracer.SetLogger(&util.LoggerAdapter{logger.With(zap.String("log.logger", "apm"))})

	config := mustLoadConfig(logger)
	if dryRun {
		logger.Info("Running dry-run mode")
		_ = initIndexer(context.Background(), logger, apmTracer, config)
		os.Exit(0)
	}

	logger.Info("Package registry started")
	defer logger.Info("Package registry stopped")

	initHttpProf(logger)

	server := initServer(logger, apmTracer, config)
	go func() {
		err := runServer(server)
		if err != nil && err != http.ErrServerClosed {
			logger.Fatal("error occurred while serving", zap.Error(err))
		}
	}()

	initMetricsServer(logger)

	stop := make(chan os.Signal, 1)
	signal.Notify(stop, os.Interrupt, syscall.SIGTERM)
	<-stop

	ctx := context.Background()
	if err := server.Shutdown(ctx); err != nil {
		logger.Fatal("error on shutdown", zap.Error(err))
	}
}

func initHttpProf(logger *zap.Logger) {
	if httpProfAddress == "" {
		return
	}

	logger.Info("Starting http pprof in " + httpProfAddress)
	go func() {
		err := http.ListenAndServe(httpProfAddress, nil)
		if err != nil {
			logger.Fatal("failed to start HTTP profiler", zap.Error(err))
		}
	}()
}

func getHostname() string {
	hostname, err := os.Hostname()
	if err != nil {
		return defaultInstanceName
	}
	return hostname
}

func initMetricsServer(logger *zap.Logger) {
	if metricsAddress == "" {
		return
	}

	hostname := getHostname()

	metrics.ServiceInfo.With(prometheus.Labels{"version": version, "instance": hostname}).Set(1)

	logger.Info("Starting http metrics in " + metricsAddress)
	go func() {
		router := http.NewServeMux()
		router.Handle("/metrics", promhttp.Handler())
		err := http.ListenAndServe(metricsAddress, router)
		if err != nil {
			logger.Fatal("failed to start Prometheus metrics endpoint", zap.Error(err))
		}
	}()
}

func initIndexer(ctx context.Context, logger *zap.Logger, apmTracer *apm.Tracer, config *Config) Indexer {
	packagesBasePaths := getPackagesBasePaths(config)

	var combined CombinedIndexer

	if featureStorageIndexer {
		storageClient, err := gstorage.NewClient(ctx)
		if err != nil {
			logger.Fatal("can't initialize storage client", zap.Error(err))
		}
		combined = append(combined, storage.NewIndexer(logger, storageClient, storage.IndexerOptions{
			APMTracer:                    apmTracer,
			PackageStorageBucketInternal: storageIndexerBucketInternal,
			PackageStorageEndpoint:       storageEndpoint,
			WatchInterval:                storageIndexerWatchInterval,
		}))
	}

	combined = append(combined,
		packages.NewZipFileSystemIndexer(logger, packagesBasePaths...),
		packages.NewFileSystemIndexer(logger, packagesBasePaths...),
	)
	ensurePackagesAvailable(ctx, logger, combined)
	return combined
}

func initServer(logger *zap.Logger, apmTracer *apm.Tracer, config *Config) *http.Server {
	tx := apmTracer.StartTransaction("initServer", "backend.init")
	defer tx.End()

	ctx := apm.ContextWithTransaction(context.TODO(), tx)

	indexer := initIndexer(ctx, logger, apmTracer, config)

	router := mustLoadRouter(logger, config, indexer)
	apmgorilla.Instrument(router, apmgorilla.WithTracer(apmTracer))

	var tlsConfig tls.Config
	if tlsMinVersionValue > 0 {
		tlsConfig.MinVersion = uint16(tlsMinVersionValue)
	}
	return &http.Server{Addr: address, Handler: router, TLSConfig: &tlsConfig}
}

func runServer(server *http.Server) error {
	if tlsCertFile != "" && tlsKeyFile != "" {
		return server.ListenAndServeTLS(tlsCertFile, tlsKeyFile)
	}
	return server.ListenAndServe()
}

func initAPMTracer() *apm.Tracer {
	apm.DefaultTracer().Close()
	if _, found := os.LookupEnv("ELASTIC_APM_SERVER_URL"); !found {
		// Don't report anything if the Server URL hasn't been configured.
		return apm.DefaultTracer()
	}

	tracer, err := apm.NewTracerOptions(apm.TracerOptions{
		ServiceName:    serviceName,
		ServiceVersion: version,
	})
	if err != nil {
		log.Fatalf("Failed to initialize APM agent: %v", err)
	}
	return tracer
}

func mustLoadConfig(logger *zap.Logger) *Config {
	config, err := getConfig(logger)
	if err != nil {
		logger.Fatal("getting config", zap.Error(err))
	}
	printConfig(logger, config)
	return config
}

func getConfig(logger *zap.Logger) (*Config, error) {
	cfg, err := ucfgYAML.NewConfigWithFile(configPath)
	if os.IsNotExist(err) {
		logger.Fatal("Configuration file is not available: " + configPath)
	}
	if err != nil {
		return nil, fmt.Errorf("reading config failed (path: %s): %w", configPath, err)
	}

	config := defaultConfig
	err = cfg.Unpack(&config)
	if err != nil {
		return nil, fmt.Errorf("unpacking config failed (path: %s): %w", configPath, err)
	}
	return &config, nil
}

func getPackagesBasePaths(config *Config) []string {
	var paths []string
	paths = append(paths, config.PackagePaths...)
	return paths
}

func printConfig(logger *zap.Logger, config *Config) {
	logger.Info("Packages paths: " + strings.Join(config.PackagePaths, ", "))
	logger.Info("Cache time for /: " + config.CacheTimeIndex.String())
	logger.Info("Cache time for /index.json: " + config.CacheTimeIndex.String())
	logger.Info("Cache time for /search: " + config.CacheTimeSearch.String())
	logger.Info("Cache time for /categories: " + config.CacheTimeCategories.String())
	logger.Info("Cache time for all others: " + config.CacheTimeCatchAll.String())
}

func ensurePackagesAvailable(ctx context.Context, logger *zap.Logger, indexer Indexer) {
	err := indexer.Init(ctx)
	if err != nil {
		logger.Fatal("Init failed", zap.Error(err))
	}

	packages, err := indexer.Get(ctx, nil)
	if err != nil {
		logger.Fatal("Cannot get packages from indexer", zap.Error(err))
	}

	if len(packages) > 0 {
		logger.Info(fmt.Sprintf("%v local package manifests loaded.", len(packages)))
	} else if featureProxyMode {
		logger.Info("No local packages found, but the proxy mode can access remote ones.")
	} else {
		logger.Fatal("No local packages found.")
	}
	metrics.NumberIndexedPackages.Set(float64(len(packages)))
}

func mustLoadRouter(logger *zap.Logger, config *Config, indexer Indexer) *mux.Router {
	router, err := getRouter(logger, config, indexer)
	if err != nil {
		logger.Fatal("failed go configure router", zap.Error(err))
	}
	return router
}

func getRouter(logger *zap.Logger, config *Config, indexer Indexer) (*mux.Router, error) {
	if featureProxyMode {
		logger.Info("Technical preview: Proxy mode is an experimental feature and it may be unstable.")
	}
	proxyMode, err := proxymode.NewProxyMode(logger, proxymode.ProxyOptions{
		Enabled: featureProxyMode,
		ProxyTo: proxyTo,
	})
	if err != nil {
		return nil, fmt.Errorf("can't create proxy mode: %w", err)
	}
	artifactsHandler := artifactsHandlerWithProxyMode(logger, indexer, proxyMode, config.CacheTimeCatchAll)
	signaturesHandler := signaturesHandlerWithProxyMode(logger, indexer, proxyMode, config.CacheTimeCatchAll)
	faviconHandleFunc, err := faviconHandler(config.CacheTimeCatchAll)
	if err != nil {
		return nil, err
	}
	indexHandlerFunc, err := indexHandler(config.CacheTimeIndex)
	if err != nil {
		return nil, err
	}

	categoriesHandler := categoriesHandlerWithProxyMode(logger, indexer, proxyMode, config.CacheTimeCategories)
	packageIndexHandler := packageIndexHandlerWithProxyMode(logger, indexer, proxyMode, config.CacheTimeCatchAll)
	searchHandler := searchHandlerWithProxyMode(logger, indexer, proxyMode, config.CacheTimeSearch)
	staticHandler := staticHandlerWithProxyMode(logger, indexer, proxyMode, config.CacheTimeCatchAll)

	router := mux.NewRouter().StrictSlash(true)
	router.HandleFunc("/", indexHandlerFunc)
	router.HandleFunc("/index.json", indexHandlerFunc)
	router.HandleFunc("/search", searchHandler)
	router.HandleFunc("/categories", categoriesHandler)
	router.HandleFunc("/health", healthHandler)
	router.HandleFunc("/favicon.ico", faviconHandleFunc)
	router.HandleFunc(artifactsRouterPath, artifactsHandler)
	router.HandleFunc(signaturesRouterPath, signaturesHandler)
	router.HandleFunc(packageIndexRouterPath, packageIndexHandler)
	router.HandleFunc(staticRouterPath, staticHandler)
	router.Use(util.LoggingMiddleware(logger))
	if metricsAddress != "" {
		router.Use(metrics.MetricsMiddleware())
	}
	router.NotFoundHandler = notFoundHandler(fmt.Errorf("404 page not found"))
	return router, nil
}

// healthHandler is used for Docker/K8s deployments. It returns 200 if the service is live
// In addition ?ready=true can be used for a ready request. Currently both are identical.
func healthHandler(w http.ResponseWriter, r *http.Request) {}