How to Parse Json log format by ConfigMap in Logstash

This is an basic example of a filter that should produce output. Although it is depending on the if statement, if that matches then the below config should work..

input {
        beats {
            port => 50XX
        }
    }
    filter {
        if [kubernetes][container][name] == "nginx" {
            json {
                source => "message"
           }
       }
    }

    output {
            elasticsearch {
                hosts => ["es-xx-01.xxxx.pro:9200", "es-xx-02.xxxx.pro:9200"]
                index => "apps-qa-%{[kubernetes][namespace]}-deployment-%{[kubernetes][pod][name]}-%{[kubernetes][labels][app]}-%{[kubernetes][container][name]}-%{+YYYY.MM.dd}"

        }
    }