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Logstash: Looping through nested JSON in ruby filter

Suppose we have a JSON payload (may be a stream coming from Kafka) that looks like this:
To loop through the nested fields and generate extra fields from the calculations while using Logstash, we can do something like this:
input {
  kafka {
    bootstrap_servers => ""
    topics => ["routerLogs"]
    group_id => "logstashConsumerGroup"
    auto_offset_reset => "earliest"
    codec => "json"
    client_id => "logstashConsumerGroupClient"

filter {
  ruby {
    code => '
      dc1NodesTraversal = 0
      dc2NodesTraversal = 0
      totalWeight = 0
      arrayLength = 0

      for currObj in event.get("nodes") do
 arrayLength += 1
        node = currObj[node]
        nodeWeight = currObj[weight].to_i

        totalWeight += nodeWeight
        if nodeWeight > 0 && node =~ /dc1/
            dc1NodesTraversal += 1
        elsif nodeWeight > 0 && node =~ /dc2/
            dc2NodesTraversal +=1

      # Below is same loop, but with different syntax, which also works
      # event.get("nodes").each_index { |i|
      #   arrayLength += 1
      #   node = event.get("[nodes]["+i.to_s+"][node]")
      #   nodeWeight = event.get("[nodes]["+i.to_s+"][weight]").to_i
      #   totalWeight += nodeWeight
      #   if nodeWeight > 0 && node =~ /dc1/
      #       dc1NodesTraversal += 1
      #   elsif nodeWeight > 0 && node =~ /dc2/
      #       dc2NodesTraversal += 1
      #   end
      # }

      event.set("dc1NodesTraversal", dc1NodesTraversal)
      event.set("dc2NodesTraversal", dc2NodesTraversal)
      event.set("totalWeight", totalWeight)
      event.set("arrayLength", arrayLength)
  mutate {
    remove_field => ["message" ]

output {
  stdout { codec => rubydebug }


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