storage_local: Don't stop fluentd start when existing file is empty. …

…ref #2373

Signed-off-by: Masahiro Nakagawa <repeatedly@gmail.com>

lib/fluent/plugin/storage_local.rb

@@ -87,7 +87,12 @@ def configure(conf)
           if File.exist?(@path)
             raise Fluent::ConfigError, "Plugin storage path '#{@path}' is not readable/writable" unless File.readable?(@path) && File.writable?(@path)
             begin
-              data = Yajl::Parser.parse(open(@path, 'r:utf-8'){ |io| io.read })
+              data = open(@path, 'r:utf-8') { |io| io.read }
+              if data.empty?
+                log.warn "detect empty plugin storage file during startup. Ignored: #{@path}"
+                return
+              end
+              data = Yajl::Parser.parse(data)
               raise Fluent::ConfigError, "Invalid contents (not object) in plugin storage file: '#{@path}'" unless data.is_a?(Hash)
             rescue => e
               log.error "failed to read data from plugin storage file", path: @path, error: e