Cannot access event['field'] after use metrics.

[MichelLiu]

Here is my logstash configuration file:

input { ... }

filter{
grok {
patterns_dir => ["/usr/local/logstash-2.3.4/patterns/"]
pattern => "%{NGINXPROXY}"
}
...

ruby {
    code "ss=event['httpstatus'];print ss" #Here can print the value
}
metrics {
    meter => "error_%{httpstatus}"
    add_tag => "metric"
    ignore_older_than => 10
}
ruby {
    code "ss=event['httpstatus'];print ss" #Here I supposed to access nginx 'httpstatus',but get result 'nil'
}

}

output {
stdout => {codec = rubydebug}
}

[IldarMinaev]

Metrics plugin generate new Logstash events. Old ones with all fields will be unavailable after metrics filter.
You can use 'add_field' to add new fields to metrics events.
Note: currently 'add_field' have issue #49 Variable interpolation does not work. You can use my changes for metrics.rb (find my comment on mentioned issue) as WA for this.