Add redis-url and redis-insecure-tls command line options

A URL can contain all of the information in the individual flags as a
single string rather than as separate pieces. I've mostly run into URLs
pointing to Redis and this make those existing URLs easier to work with.

This also introduces the -redis-insecure-tls flag which turns off TLS
certificate hostname verification. We've chosen Heroku Redis for a
recent project which requires TLS but, for reasons I don't know, they
don't provide a certificate that is valid for the hostname. I also
wasn't able to get the existing -redis-tls flag to work.

main.go

@@ -26,14 +26,18 @@ var (
 	flagRedisDB          int
 	flagRedisPassword    string
 	flagRedisTLS         string
+	flagRedisURL         string
+	flagRedisInsecureTLS bool
 )
 
 func init() {
 	flag.IntVar(&flagPort, "port", 8080, "port number to use for web ui server")
-	flag.StringVar(&flagRedisAddr, "redis_addr", "127.0.0.1:6379", "address of redis server to connect to")
-	flag.IntVar(&flagRedisDB, "redis_db", 0, "redis database number")
-	flag.StringVar(&flagRedisPassword, "redis_password", "", "password to use when connecting to redis server")
-	flag.StringVar(&flagRedisTLS, "redis_tls", "", "server name for TLS validation used when connecting to redis server")
+	flag.StringVar(&flagRedisAddr, "redis-addr", "127.0.0.1:6379", "address of redis server to connect to")
+	flag.IntVar(&flagRedisDB, "redis-db", 0, "redis database number")
+	flag.StringVar(&flagRedisPassword, "redis-password", "", "password to use when connecting to redis server")
+	flag.StringVar(&flagRedisTLS, "redis-tls", "", "server name for TLS validation used when connecting to redis server")
+	flag.StringVar(&flagRedisURL, "redis-url", "", "URL to redis server")
+	flag.BoolVar(&flagRedisInsecureTLS, "redis-insecure-tls", false, "Disable TLS certificate host checks")
 }
 
 // staticFileServer implements the http.Handler interface, so we can use it
@@ -85,31 +89,57 @@ func (srv *staticFileServer) indexFilePath() string {
 	return filepath.Join(srv.staticDirPath, srv.indexFileName)
 }
 
+func getRedisOptionsFromFlags() (*redis.Options, error) {
+	var err error
+	var opts *redis.Options
+
+	if flagRedisURL != "" {
+		opts, err = redis.ParseURL(flagRedisURL)
+		if err != nil {
+			return nil, err
+		}
+	} else {
+		opts = &redis.Options{
+			Addr:      flagRedisAddr,
+			DB:        flagRedisDB,
+			Password:  flagRedisPassword,
+			TLSConfig: &tls.Config{},
+		}
+	}
+
+	if tls := opts.TLSConfig; tls != nil {
+		if tlsHost := flagRedisTLS; tlsHost != "" {
+			tls.ServerName = tlsHost
+		}
+
+		if flagRedisInsecureTLS {
+			tls.InsecureSkipVerify = true
+		}
+	}
+
+	return opts, nil
+}
+
 //go:embed ui/build/*
 var staticContents embed.FS
 
 func main() {
 	flag.Parse()
 
-	var tlsConfig *tls.Config
-	if flagRedisTLS != "" {
-		tlsConfig = &tls.Config{ServerName: flagRedisTLS}
+	opts, err := getRedisOptionsFromFlags()
+	if err != nil {
+		log.Fatal(err)
 	}
 
 	inspector := inspeq.New(asynq.RedisClientOpt{
-		Addr:      flagRedisAddr,
-		DB:        flagRedisDB,
-		Password:  flagRedisPassword,
-		TLSConfig: tlsConfig,
+		Addr:      opts.Addr,
+		DB:        opts.DB,
+		Password:  opts.Password,
+		TLSConfig: opts.TLSConfig,
 	})
 	defer inspector.Close()
 
-	rdb := redis.NewClient(&redis.Options{
-		Addr:      flagRedisAddr,
-		DB:        flagRedisDB,
-		Password:  flagRedisPassword,
-		TLSConfig: tlsConfig,
-	})
+	rdb := redis.NewClient(opts)
 	defer rdb.Close()
 
 	router := mux.NewRouter()

redis_info_handlers.go

@@ -30,7 +30,7 @@ func newRedisInfoHandlerFunc(rdb *redis.Client) http.HandlerFunc {
 		}
 		info := parseRedisInfo(res)
 		resp := RedisInfoResponse{
-			Addr:    flagRedisAddr,
+			Addr:    rdb.Options().Addr,
 			Info:    info,
 			RawInfo: res,
 		}