support proxy prefix

cmd/gonic/main.go

@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"log"
 	"os"
+	"regexp"
 	"time"
 
 	_ "github.com/jinzhu/gorm/dialects/sqlite"
@@ -21,6 +22,7 @@ func main() {
 	musicPath := set.String("music-path", "", "path to music")
 	dbPath := set.String("db-path", "gonic.db", "path to database (optional)")
 	scanInterval := set.Int("scan-interval", 0, "interval (in minutes) to automatically scan music (optional)")
+	proxyPrefix := set.String("proxy-prefix", "", "url path prefix to use if behind proxy. eg '/gonic' (optional)")
 	_ = set.String("config-path", "", "path to config (optional)")
 	showVersion := set.Bool("version", false, "show gonic version")
 	if err := ff.Parse(set, os.Args[1:],
@@ -42,11 +44,14 @@ func main() {
 		log.Fatalf("error opening database: %v\n", err)
 	}
 	defer db.Close()
+	proxyPrefixExpr := regexp.MustCompile(`^\/*(.*?)\/*$`)
+	*proxyPrefix = proxyPrefixExpr.ReplaceAllString(*proxyPrefix, `/$1`)
 	serverOptions := server.Options{
 		DB:           db,
 		MusicPath:    *musicPath,
 		ListenAddr:   *listenAddr,
 		ScanInterval: time.Duration(*scanInterval) * time.Minute,
+		ProxyPrefix:  *proxyPrefix,
 	}
 	log.Printf("using opts %+v\n", serverOptions)
 	s := server.New(serverOptions)