Fluent-bit - Splitting json log into structured fields in Elasticsearch

Solution is as follows.

[SERVICE]
    Flush        5
    Daemon       Off
    Log_Level    debug
    Parsers_File parsers.conf

[INPUT]
    Name         forward
    storage.type filesystem
    Listen       my_fluent_bit_service
    Port         24224

[FILTER]
    Name         parser
    Parser       docker
    Match        hello_*
    Key_Name     log
    Reserve_Data On
    Preserve_Key On

[OUTPUT]
    Name            es
    Host            my_elasticsearch_service
    Port            9200
    Match           hello_*
    Index           hello
    Type            logs
    Include_Tag_Key On
    Tag_Key         tag

[PARSER]
    Name         docker
    Format       json
    Time_Key     time
    Time_Format  %Y-%m-%dT%H:%M:%S.%L
    Time_Keep    On
    # Command      |  Decoder | Field | Optional Action
    # =============|==================|=================
    Decode_Field_As   escaped_utf8    log    do_next
    Decode_Field_As   json       log