How do I output metadata when exporting data from elasticsearch with logstash?

[eeijlar]

I am using the following pipeline in logstash:

    - pipeline.id: export-process
      pipeline.workers: 4
      config.string: |
        input {
          elasticsearch {
            hosts => "http://localhost:9200"
            ssl => "false"
            index => "metricbeat-*"
            docinfo => true
            }
            query => '{
                "query": {
                  "bool": {
                    "filter": {
                      "range": {
                          "@timestamp": {
                          "gte": "now-30m",
                          "lte": "now",
                          "format": "strict_date_optional_time||epoch_millis"
                          }
                      }
                    }
                  }
              }
            }'            
          }
        }

        output {
          file {
            gzip => "true"
            path => "/usr/share/logstash/export/export_%{[@metadata][_index]}.json.gz"
          }
        }  

This works as expected, however each line of the output comes out like this:

{
  "@version": "1",
  "host": {
    "name": "monitoring-fb-beat-filebeat-2h7t4"
  },
  "agent": {
    "hostname": "monitoring-fb-beat-filebeat-2h7t4",
    "name": "monitoring-fb-beat-filebeat-2h7t4",
    "id": "44f948e3-5eb6-4afa-95b5-53b39bc661df",
    "type": "filebeat",
    "ephemeral_id": "6ad248a8-028d-4914-9a54-65b8e9222ace",
    "version": "7.17.7"
  },
  "log": {
    "offset": 290242,
    "file": {
      "path": "/var/log/containers/monitoring-mb-beat-metricbeat-gchp5_monitoring_metricbeat-b63cb08adec937a56e887472e2a308839203005eb4f8ea974c284100babf9c4f.log"
    }
  },
  "kubernetes": {
    "namespace_labels": {
      "kubernetes_io/metadata_name": "monitoring"
    },
    "namespace": "monitoring",
    "node": {
      "labels": {
        "topology_kubernetes_io/zone": "eu-west-1b",
        "node_kubernetes_io/instance-type": "m6i.12xlarge",
        "beta_kubernetes_io/instance-type": "m6i.12xlarge",
        "k8s_io/cloud-provider-aws": "d40d2d858cc11fa6d9e2ec8bccacd30f",
        "topology_ebs_csi_aws_com/zone": "eu-west-1b",
        "beta_kubernetes_io/os": "linux",
        "kubernetes_io/os": "linux",
        "kubernetes_io/arch": "amd64",
        "beta_kubernetes_io/arch": "amd64",
      },
      "uid": "adb67c03-193f-4430-8bdc-071bcdac0826"
    },
    "daemonset": {
      "name": "monitoring-mb-beat-metricbeat"
    },
    "labels": {
      "controller-revision-hash": "58b65ddf9b",
      "chart": "monitoring-4.3.0",
      "common_k8s_elastic_co/type": "beat",
      "heritage": "Helm",
      "beat_k8s_elastic_co/name": "monitoring-mb",
      "stack-monitoring_elastic_co/type": "beat",
      "app": "monitoring-metricbeat",
      "release": "monitoring",
      "beat_k8s_elastic_co/version": "7.17.7",
      "pod-template-generation": "1"
    },
    "namespace_uid": "6beaefed-9f0e-4367-9dfb-2b2598db6f32",
    "container": {
      "name": "metricbeat"
    },
    "pod": {
      "name": "monitoring-mb-beat-metricbeat-gchp5",
      "uid": "3bc401f3-cf13-4a60-9a66-b25384fdd575"
    }
  },
  "input": {
    "type": "container"
  },
  "container": {
    "runtime": "docker",
    "image": {
      "name": "10.2.1.2:5000/beats/metricbeat:7.17.7"
    },
    "id": "b63cb08adec937a56e887472e2a308839203005eb4f8ea974c284100babf9c4f"
  },
  "@timestamp": "2023-03-13T08:04:17.013Z",
  "message": "2023-03-13T08:04:17.013Z\tWARN\t[transport]\ttransport/tcp.go:52\tDNS lookup failure \"odf-cluster-zookeeper-metrics.odf\": lookup odf-cluster-zookeeper-metrics.odf on 172.20.0.10:53: no such host",
  "stream": "stderr",
  "ecs": {
    "version": "1.12.0"
  }
}

This however, has no metadata. It doesn't contain which index it came from etc, fields like:

        "_index" : "metricbeat-12-22-23",
        "_type" : "_doc",
        "_id" : "gE6t4IYB7RMHyt2kHhRw",
        "_score" : 1.0,

So, when I try and import the same json file into another elastic instance, it doesn't get indexed properly, it just goes in as a blob, with a bunch of fields all bundled under the same object. From reading the documentation I need to add the following:

            docinfo_target => "[@metadata][doc]"
              add_field => {
                identifier => "%{[@metadata][doc][_index]}:%{[@metadata][doc][_type]}:%{[@metadata][doc][_id]}"
            }

to the input section. This just the breaks export though.. and the output file is corrupted. What is the correct way to do this?