Ruby Script to rename fields base on a dictionary

Elastic Stack Logstash
1

Hello,
we use in a logstash pipeline an external ruby script which contains several methods to process logfiles.
now we want to add a new method to rename all top level fields of a document based on a hashtable.
I have adapted a method that was used to filter nested fields.

def filter(event)
    transformKnownFields(event)
    return [event]
end

def transformKnownFields(event)
    events = event.get()
    for k,v in events do
        fieldname = k.downcase
        if fieldname == "elapsed"
            v = v*1000
        end
        ecsfield = $ecsmappings[fieldname]
        event.set(ecsfield, v)
        event.remove(k)
    end
end

$ecsmappings = {
"action" => "[event][action]",
"actionname" => "[event][action]",
"controller" => "[event][category]",
"controllername" => "[event][category]",
"correlationid" => "[trace][id]",
"culture" => "[client][geo][region_iso_code]",
"duration" => "[event][duration]", 
"elapsed" => "[event][duration]",
"elapsedmilliseconds" => "[event][duration]",
"exception" => "[error][type]",
"exceptionmessage" => "[error][message]",
"host" => "[url][domain]",
"httpmethod" => "[http][request][method]",
"level" => "[log][level]", 
"machinename" => "[host][name]"
}

Unfortunately it doesn't work like that. i also tried to use "event.to.hash" but i had no luck.

i'm not very familiar with ruby and i'm not really getting anywhere for days now. can someone give me please some advise

regards,
Frank

2

Try this

    ruby {
        init => '
            @ecsmappings = {
                "action" => "[event][action]",
                "actionname" => "[event][action]",
                "controller" => "[event][category]",
                "controllername" => "[event][category]",
                "correlationid" => "[trace][id]",
                "culture" => "[client][geo][region_iso_code]",
                "duration" => "[event][duration]",
                "elapsed" => "[event][duration]",
                "elapsedmilliseconds" => "[event][duration]",
                "exception" => "[error][type]",
                "exceptionmessage" => "[error][message]",
                "host" => "[url][domain]",
                "httpmethod" => "[http][request][method]",
                "level" => "[log][level]",
                "machinename" => "[host][name]"
            }
        '
        code => '
            event.to_hash.each { |k, v|
                fieldname = k.downcase
                if fieldname == "elapsed"
                    v = v*1000
                end
                ecsfield = @ecsmappings[fieldname]
                if ecsfield
                    event.set(ecsfield, v)
                    event.remove(k)
                end
            }
        '
    }
3

Hy Badger,
thanks for the quick reply. unfortunately the code doesn't work when i put it in our external ruby script that is called from within logstash pipeline.

i assume that this example only works directly in the pipeline or?
is it not possible to use the event.to_hash function in external ruby scripts?

regards,
Frank

4

You could use the same code in your transformKnownFields method.

5

Hi,
thank you. I finally figured it out, there was a small mistake on my side.

regards,
Frank

6

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