[#233] get/head: Middleware refactor

Add:
 * search index.html
 * fallback by leading slash
Signed-off-by: Denis Kirillov <d.kirillov@yadro.com>

cmd/http-gw/app.go

@@ -100,17 +100,18 @@ type (
 		workerPoolSize    int
 		logLevelConfig    *logLevelConfig
 
-		mu                     sync.RWMutex
-		defaultTimestamp       bool
-		archiveCompression     bool
-		clientCut              bool
-		returnIndexPage        bool
-		indexPageTemplate      string
-		bufferMaxSizeForPut    uint64
-		namespaceHeader        string
-		defaultNamespaces      []string
-		cors                   *data.CORSRule
-		enableFilepathFallback bool
+		mu                          sync.RWMutex
+		defaultTimestamp            bool
+		archiveCompression          bool
+		clientCut                   bool
+		returnIndexPage             bool
+		indexPageTemplate           string
+		bufferMaxSizeForPut         uint64
+		namespaceHeader             string
+		defaultNamespaces           []string
+		cors                        *data.CORSRule
+		enableFilepathFallback      bool
+		enableFilepathSlashFallback bool
 	}
 
 	tagsConfig struct {
@@ -296,6 +297,7 @@ func (s *appSettings) update(v *viper.Viper, l *zap.Logger) {
 	indexPage, indexEnabled := fetchIndexPageTemplate(v, l)
 	cors := fetchCORSConfig(v)
 	enableFilepathFallback := v.GetBool(cfgFeaturesEnableFilepathFallback)
+	enableFilepathSlashFallback := v.GetBool(cfgFeaturesEnableFilepathSlashFallback)
 
 	s.mu.Lock()
 	defer s.mu.Unlock()
@@ -311,6 +313,7 @@ func (s *appSettings) update(v *viper.Viper, l *zap.Logger) {
 	s.indexPageTemplate = indexPage
 	s.cors = cors
 	s.enableFilepathFallback = enableFilepathFallback
+	s.enableFilepathSlashFallback = enableFilepathSlashFallback
 }
 
 func (s *loggerSettings) DroppedLogsInc() {
@@ -421,6 +424,12 @@ func (s *appSettings) EnableFilepathFallback() bool {
 	return s.enableFilepathFallback
 }
 
+func (s *appSettings) EnableFilepathSlashFallback() bool {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+	return s.enableFilepathSlashFallback
+}
+
 func (a *app) initResolver() {
 	var err error
 	a.resolver, err = resolver.NewContainerResolver(a.getResolverConfig())