Trap and report exception with invalid interpolated timezone better

[prehor]

When I use interpolated variable for timezone I got exception:

{
    :timestamp=>"2016-06-12T21:11:52.153000+0000", 
    :message=>"Failed parsing date from field", 
    :field=>"[@metadata][syslog][timestamp]", 
    :value=>"Jun 12 03:13:22", 
    :exception=>"wrong number of arguments (2 for 1)", 
    :config_parsers=>"MMM dd HH:mm:ss,MMM  d HH:mm:ss", 
    :config_locale=>"default=en", 
    :level=>:warn
}

Filter configuration:

date {
    match => [
        "[@metadata][syslog][timestamp]",
        "MMM dd HH:mm:ss",
        "MMM  d HH:mm:ss"
    ]
    locale => "en"
    timezone => "%{[@metadata][syslog][timezone]}"
    tag_on_failure => "invalid_timestamp"
}

[@metadata][syslog][timezone] contains "Europe/Prague"

When I use timezone => "Europe/Prague" timestamp is parsed without error.

I'm using Logstash 2.3.2 in Docker.

[prehor]

I have investigated the problem and found a mistake in may configuration - [@metadata][syslog][timezone] does not contains valid zone name for some hosts and it was the root of the problem.

Would it be possible to add information about used timezone to the exception?

[guyboertje]

If a interpolated string that is not a supported Timezone string we get an exception and a parse failure but it is not reported very well. e.g. Europe/Berlim.