Can hdfs path use ${tag} or ${record} ? just like: /data/hdfs/${tag}.#{Socket.gethostname}.log

Hello,
I use 'fluent-plugin-webhdfs' version '1.2.2', fluentd version: 1.4
My log file looks like:
`interface=login&time=20170925&...others fields...`
In my td-agent config file, I named my log as a tag:interface.login.hdfs
```

@type tail
format none
path /data/td-agent/logs/interface.log
pos_file /etc/td-agent/pos/interface.pos
read_from_head true
tag interface.**login**.hdfs

@type webhdfs
host *.*.*.*
port 50070
path /data/gamelogs/hdfs/date=${record['time']}/${tag[2]}.#{Socket.gethostname}.log

@type json

```
and I need to get "login" from tag, and get time from my log record, so if there has any method to get these two values?

In some other plugins, I can use $tag[2] or ${record['interface']}, ${record['time']} to get these values,but in this plugin, it doesn't work.
Thanks...