Dynamic topic for output kafka in fluentbit

fluentbit.conf

Place below config in fluent bit.config. And annotate your pods with `k8s_annotations_fluentbit.topic : <destination-topic>`.
For the pods which have this annotation defined, kafka will output : respective `<destination-topic>`

    [FILTER]
        Name kubernetes
        Match kube.*
        Merge_Log On
        Keep_Log Off
        K8S-Logging.Parser On
        K8S-Logging.Exclude On
    
    [FILTER]
        Name nest
        Match *
        Operation lift
        Nested_under kubernetes
        Add_prefix kubernetes_

    [FILTER]
        Name nest
        Match *
        Operation lift
        Nested_under kubernetes_annotations
        Add_prefix k8s_annotations_

    [FILTER]
        Name nest
        Match *
        Operation nest
        Wildcard kubernetes_*
        Nest_under kubernetes

    [OUTPUT]
        Name kafka
        Match kube.*
        Brokers ${KAFKA_BROKER}
        Topics default_topic_here
        Topic_key k8s_annotations_fluentbit.topic
        Dynamic_topic On
        ...remaining config