问如何从日志文件路径中提取变量，测试Logstash中模式的日志文件名？

EN

resources/environments/logs/publish/e-3ykfgdfgmp8/i-cf216955/_var_log_nginx_rotated_access.log1417633261.gz

_var_log_eb-docker_containers_eb-current-app_rotated_application.log1417586461.gz
_var_log_eb-docker_containers_eb-current-app_rotated_application.log1417597261.gz
_var_log_rotated_docker1417579261.gz
_var_log_rotated_docker1417582862.gz
_var_log_rotated_docker-events.log1417579261.gz
_var_log_nginx_rotated_access.log1417633261.gz

input {
        s3 {
                debug => "true"
                bucket => "elasticbeanstalk-us-east-1-something"
                region => "us-east-1"
                region_endpoint => "us-east-1"
                credentials => ["..."]
                prefix => "resources/environments/logs/publish/"
                sincedb_path => "/tmp/s3.sincedb"
                backup_to_dir => "/tmp/logstashed/"
                tags => ["s3","elastic_beanstalk"]
                type => "elastic_beanstalk"
        }
}

filter {
 if [type] == "elastic_beanstalk" {
  grok {
    match => [ "@source_path", "resources/environments/logs/publish/%{environment}/%{instance}/%{file}<unnecessary_number>.gz" ]
  }
 }
}

filter {
     if [type] == "elastic_beanstalk" {
       if [file_name] BEGINS WITH "application_custom_log" {
         grok {

            match => [ "message", "%{IP:client} %{WORD:method} %{URIPATHPARAM:request} %{NUMBER:bytes} %{NUMBER:duration}" ]

         }
       }

       if [file_name] BEGINS WITH "some_other_custom_log" {
        ....
       }
     }
    }