Split filebeat name

[Zareh42]

I am trying to implement the filter below. And continue to get an error about

Invalid FieldReference: `%{[beat][hostname]}`

I believe I am calling the field correctly based on the guide here

filter {
        mutate {
        split => [ "%{[beat][hostname]}", "." ]
        add_field => { "test_shortname" => "%{[beat][hostname][0]}" }
    }  
}

I recently started working on this recently so I am still very new to elastic

[Badger]

You cannot use a sprintf reference in the split option like that. Try

mutate {
    split => [ "[beat][hostname]", "." ]
    add_field => { "test_shortname" => "%{[beat][hostname][0]}" }
}

[Zareh42]

Thank you that worked. Really appreciate it, I must have missed that somewhere in the documentation.