cx noticed log JSON change after migrating fluentd to vector.

For instance:
・istiod.log
before:
ip-10-249-81-55.ap-northeast-1.compute.internal istiod-basic-7cd97fbd-89nvb 2024-05-16T05:24:35.873035Z info ads RDS: PUSH request for node:httpd-test-64f98c577d-qnlkv.hitachi-test resources:16 size:24.7kB cached:0/16
after:
istiod-basic-7cd97fbd-89nvb 2024-05-16T05:24:35.873035Z info ads RDS: PUSH request for node:httpd-test-64f98c577d-qnlkv.hitachi-test resources:16 size:24.7kB cached:0/16

⇒ip-10-249-81-55.ap-northeast-1.compute.internal is gone.

Workaround:
made change to rsyslog.conf(cx's output server) as follows:
property(name="$!kubernetes!host")
↓
property(name="$!hostname")

Reason for the WA can see host format is different:
Fluentd JSON:
{
  "_index": "app-000001",
  "_type": "_doc",
  "_id": "NTk2NWI1ODktZDk1My00MjcyLWE4ZmQtNThjYWRiZDVlYTAw",
  "_version": 1,
  "_score": null,
  "_source": {
    "kubernetes": {
      "container_image_id": "registry.redhat.io/openshift-service-mesh/pilot-rhel8@sha256:b451f504cb2078f363a4b184e4223289908ddf499f68bdee99f65350035276a6",
      "container_name": "discovery",
      "namespace_id": "1dcdcbf8-9f58-456a-9a6f-21e00fdbd669",
      "flat_labels": [
        "app=istiod",
        "istio=istiod",
        "istio_io_rev=basic",
        "maistra-control-plane=istio-system",
        "pod-template-hash=c754cb9cf",
        "sidecar_istio_io_inject=false"
      ],
      "pod_ip": "10.131.2.31",
      "host": "hollytest-wbxlb-worker-eastus1-j8r6x",
      "master_url": "https://kubernetes.default.svc",
      "pod_id": "f051a874-95f1-4817-9bef-69ed48a46827",
      "namespace_labels": {
        "pod-security_kubernetes_io_audit": "restricted",
        "maistra_io_member-of": "istio-system",
        "pod-security_kubernetes_io_warn-version": "v1.24",
        "pod-security_kubernetes_io_warn": "restricted",
        "kubernetes_io_metadata_name": "istio-system",
        "kiali_io_member-of": "istio-system",
        "pod-security_kubernetes_io_audit-version": "v1.24"
      },
      "container_image": "registry.redhat.io/openshift-service-mesh/pilot-rhel8@sha256:f12207461e6613649d6c62eea7bdf00829715249068796d59ba2fe99c19948ae",
      "namespace_name": "istio-system",
      "pod_name": "istiod-basic-c754cb9cf-xbwqr"
    },
    "viaq_msg_id": "NTk2NWI1ODktZDk1My00MjcyLWE4ZmQtNThjYWRiZDVlYTAw",
    "level": "info",
    "openshift": {
      "sequence": 585,
      "cluster_id": "938c0ea1-838f-420c-a1ff-2352058b517b"
    },
    "message": "2024-05-17T08:09:03.573347Z\tinfo\tads\tLDS: PUSH for node:istio-ingressgateway-69f8699479-bhshr.istio-system resources:1 size:2.5kB",  
    "docker": {
      "container_id": "bbb58ae23d1226db7f13d5193a0c5ec4ac6f10d67fee321a8b41361f55498c45"
    },
    "hostname": "hollytest-wbxlb-worker-eastus1-j8r6x",
    "log_type": "application",
    "@timestamp": "2024-05-17T08:09:03.573383221+00:00",
    "pipeline_metadata": {
      "collector": {
        "received_at": "2024-05-17T08:09:03.579057+00:00",
        "name": "fluentd",
        "inputname": "fluent-plugin-systemd",
        "version": "1.16.2 1.6.0",
        "ipaddr4": "10.0.4.136"
      }
    }
  },
  "fields": {
    "@timestamp": [
      "2024-05-17T08:09:03.573Z"
    ],
    "pipeline_metadata.collector.received_at": [
      "2024-05-17T08:09:03.579Z"
    ]
  },
  "highlight": {
    "message": [
      "2024-05-17T08:09:03.573347Z\tinfo\tads\tLDS: @kibana-highlighted-field@PUSH@/kibana-highlighted-field@ for node:istio-ingressgateway-69f8699479-bhshr.istio-system resources:1 size:2.5kB"
    ],
    "kubernetes.namespace_name": [
      "@kibana-highlighted-field@istio-system@/kibana-highlighted-field@"
    ]
  },
  "sort": [
    1715933343573
  ]
}

------------------------------------------

Vector JSON：

{
  "_index": "app-000001",
  "_type": "_doc",
  "_id": "YzRkZWI0N2UtYmUxMS00YWI4LTg2MzAtYmY3MWVkZTc3ZmI1",
  "_version": 1,
  "_score": null,
  "_source": {
    "kubernetes": {
      "pod_ip": "10.131.1.143",
      "annotations": {
        "seccomp.security.alpha.kubernetes.io/pod": "runtime/default",
        "prometheus.io/port": "15014",
        "sidecar.istio.io/inject": "false",
        "ambient.istio.io/redirection": "disabled",
        "prometheus.io/scrape": "true",
        "openshift.io/scc": "restricted-v2",
        "k8s.ovn.org/pod-networks": "{\"default\":{\"ip_addresses\":[\"10.131.1.143/23\"],\"mac_address\":\"0a:58:0a:83:01:8f\",\"gateway_ips\":[\"10.131.0.1\"],\"ip_address\":\"10.131.1.143/23\",\"gateway_ip\":\"10.131.0.1\"}}",
        "k8s.v1.cni.cncf.io/network-status": "[{\n    \"name\": \"ovn-kubernetes\",\n    \"interface\": \"eth0\",\n    \"ips\": [\n        \"10.131.1.143\"\n    ],\n    \"mac\": \"0a:58:0a:83:01:8f\",\n    \"default\": true,\n    \"dns\": {}\n}]"
      },
      "pod_owner": "ReplicaSet/istiod-basic-5794cf67bb",
      "namespace_labels": {
        "pod-security_kubernetes_io_audit": "restricted",
        "maistra_io_member-of": "istio-system",
        "pod-security_kubernetes_io_warn-version": "v1.24",
        "pod-security_kubernetes_io_warn": "restricted",
        "kubernetes_io_metadata_name": "istio-system",
        "kiali_io_member-of": "istio-system",
        "pod-security_kubernetes_io_audit-version": "v1.24"
      },
      "container_image": "registry.redhat.io/openshift-service-mesh/pilot-rhel8@sha256:f12207461e6613649d6c62eea7bdf00829715249068796d59ba2fe99c19948ae",
      "labels": {},
      "namespace_name": "istio-system",
      "pod_name": "istiod-basic-5794cf67bb-7kt4g",
      "container_name": "discovery",
      "flat_labels": [
        "istio=istiod",
        "pod-template-hash=5794cf67bb",
        "app=istiod",
        "istio_io_rev=basic",
        "maistra-control-plane=istio-system",
        "sidecar_istio_io_inject=false"
      ],
      "namespace_id": "1dcdcbf8-9f58-456a-9a6f-21e00fdbd669",
      "pod_id": "d2f7d700-cd5a-4ed5-848e-14d9825fe264",
      "container_id": "cri-o://6e4df9af8a5eaba793eee288a867abb15fcacc98dee530422f2bf63c5d615ef0"
    },
    "hostname": "hollytest-wbxlb-worker-eastus3-nh85b",
    "log_type": "application",
    "@timestamp": "2024-05-17T07:45:43.319246645Z",
    "level": "info",
    "openshift": {
      "sequence": 139860,
      "cluster_id": "938c0ea1-838f-420c-a1ff-2352058b517b"
    },
    "message": "2024-05-17T07:45:43.319208Z\tinfo\tads\tSDS: PUSH request for node:istio-ingressgateway-5bdb858658-dnnqh.istio-system resources:1 size:2.8kB cached:1/1" 　　
  },
  "fields": {
    "@timestamp": [
      "2024-05-17T07:45:43.319Z"
    ]
  },
  "highlight": {
    "kubernetes.namespace_name": [
      "@kibana-highlighted-field@istio-system@/kibana-highlighted-field@"
    ]
  },
  "sort": [
    1715931943319
  ]
}