run.txt

% echo '{ "array": [ { "one": 1 }, { "two": 2 }, { "three": 3 } ] }' | bin/logstash -f test.conf
{
  "one"        => 1,
  "@version"   => "1",
  "@timestamp" => "2015-01-29T01:09:02.813Z"
}
{
  "two"        => 2,
  "@version"   => "1",
  "@timestamp" => "2015-01-29T01:09:02.814Z"
}
{
  "three"      => 3,
  "@version"   => "1",
  "@timestamp" => "2015-01-29T01:09:02.814Z"
}

test.conf

input { stdin { codec => json_lines } }

filter {
  ruby {
    init => "def filter(event, &block); event['array'].each { |o| yield LogStash::Event.new(o) }; event.cancel; end"
    code => "hahaha"
  }
}

output { stdout { codec => rubydebug } }