Kubernetes pod name/service name as index name in Kibana using fluentd - elasticsearch

Question

Currently we have many services running on k8s and sending logs with fluent-bit to elastic using fluentd.
In fluentd we have hard coded logstash_prefix xxx-logstash, so all logs are created with the same index. Now we want to send data to elastic with respect to podname/service name.
From the json document of logs in kibana, we see there is a key PodName, but how to use this in fluentd.conf? We are using helm for elastic stack deployment.
fluentd.conf
#see more ddetails in https://github.com/uken/fluent-plugin-elasticsearch
apiVersion: v1
kind: ConfigMap
metadata:
name: elasticsearch-output
data:
fluentd.conf: |
#configure the logging level to error
<system>
log_level error
</system>
# Ignore fluentd own events
<label #FLUENT_LOG>
<match fluent.**>
#type null
</match>
</label>
# TCP input to receive logs from the forwarders
<source>
#type forward
bind 0.0.0.0
port 24224
</source>
# HTTP input for the liveness and readiness probes
<source>
#type http
bind 0.0.0.0
port 9880
</source>
# Throw the healthcheck to the standard output instead of forwarding it
<match fluentd.healthcheck>
#type null
</match>
# Send the logs to the standard output
<match **>
#type elasticsearch
include_tag_key true
host "{{ .Release.Name }}-es-http"
port "9200"
user "elastic"
password "{{ (.Values.env.secret.password | b64dec) | indent 4 | trim }}"
logstash_format true
scheme https
ssl_verify false
logstash_prefix xxx-logstash
logstash_prefix_separator -
logstash_dateformat %Y.%m.%d
<buffer>
#type file
path /opt/bitnami/fluentd/logs/buffers/logs.buffer
flush_thread_count 2
flush_interval 5s
</buffer>
</match>
** Sample log document from Kibana**
{
"_index": "xxx-logstash-2022.08.19",
"_type": "_doc",
"_id": "N34ntYIBvWtHvFBZmz-L",
"_version": 1,
"_score": 1,
"_ignored": [
"message.keyword"
],
"_source": {
"FileName": "/app/logs/app.log",
"#timestamp": "2022-08-19T08:10:46.854Z",
"#version": "1",
"message": "[com.couchbase.endpoint][EndpointConnectionFailedEvent][1485us] Connect attempt 16569 failed because of : finishConnect(..) failed: Connection refused: xxx-couchbase-cluster.couchbase/10.244.27.5:8091 - Check server ports and cluster encryption setting. {\"circuitBreaker\":\"DISABLED\",\"coreId\":\"0x94bd86a800000002\",\"remote\":\"xxx-couchbase-cluster.couchbase:8091\",\"type\":\"MANAGER\"}",
"logger_name": "com.couchbase.endpoint",
"thread_name": "cb-events",
"level": "WARN",
"level_value": 30000,
"stack_trace": "com.couchbase.client.core.endpoint.BaseEndpoint$2: finishConnect(..) failed: Connection refused: xxx-couchbase-cluster.couchbase/10.244.27.5:8091 - Check server ports and cluster encryption setting.\n",
"PodName": "product-59b7f4b567-r52vn",
"Namespace": "designer-dev",
"tag": "tail.0"
},
"fields": {
"thread_name.keyword": [
"cb-events"
],
"level": [
"WARN"
],
"FileName": [
"/app/logs/app.log"
],
"stack_trace.keyword": [
"com.couchbase.client.core.endpoint.BaseEndpoint$2: finishConnect(..) failed: Connection refused: xxx-couchbase-cluster.couchbase/10.244.27.5:8091 - Check server ports and cluster encryption setting.\n"
],
"PodName.keyword": [
"product-59b7f4b567-r52vn"
],
"#version.keyword": [
"1"
],
"message": [
"[com.couchbase.endpoint][EndpointConnectionFailedEvent][1485us] Connect attempt 16569 failed because of : finishConnect(..) failed: Connection refused: xxx-couchbase-cluster.couchbase/10.244.27.5:8091 - Check server ports and cluster encryption setting. {\"circuitBreaker\":\"DISABLED\",\"coreId\":\"0x94bd86a800000002\",\"remote\":\"xxx-couchbase-cluster.couchbase:8091\",\"type\":\"MANAGER\"}"
],
"Namespace": [
"designer-dev"
],
"PodName": [
"product-59b7f4b567-r52vn"
],
"#timestamp": [
"2022-08-19T08:10:46.854Z"
],
"level.keyword": [
"WARN"
],
"thread_name": [
"cb-events"
],
"level_value": [
30000
],
"Namespace.keyword": [
"designer-dev"
],
"#version": [
"1"
],
"logger_name": [
"com.couchbase.endpoint"
],
"tag": [
"tail.0"
],
"stack_trace": [
"com.couchbase.client.core.endpoint.BaseEndpoint$2: finishConnect(..) failed: Connection refused: xxx-couchbase-cluster.couchbase/10.244.27.5:8091 - Check server ports and cluster encryption setting.\n"
],
"tag.keyword": [
"tail.0"
],
"FileName.keyword": [
"/app/logs/app.log"
],
"logger_name.keyword": [
"com.couchbase.endpoint"
]
},
"ignored_field_values": {
"message.keyword": [
"[com.couchbase.endpoint][EndpointConnectionFailedEvent][1485us] Connect attempt 16569 failed because of : finishConnect(..) failed: Connection refused: xxx-couchbase-cluster.couchbase/10.244.27.5:8091 - Check server ports and cluster encryption setting. {\"circuitBreaker\":\"DISABLED\",\"coreId\":\"0x94bd86a800000002\",\"remote\":\"xxx-couchbase-cluster.couchbase:8091\",\"type\":\"MANAGER\"}"
]
}
}