Logstash parsing json string fields, merging, and replacing event

logstash.conf

# test as follows:

# 1. start logstash: 
# logstash -f ~/logstash.conf --config.reload.automatic

# 2. send it data:
# echo '{"container": "/spiff", "bleh": "blah"}' | nc localhost 6060

input {
    tcp {
		port => 6060
	}
}


filter {
    # merge json fields to top-level event
    if [message] {
        if [message] =~ "\A\{.+\}\z" {
        ruby {
            code => '
                    msgObj = JSON.parse(event.get("message"))
                    msgObj.each { |k,v|
                        event.set("#{k}", v)
                    }
                    event.remove("message")
            '
            }
        }
    }

    # # convert a field "message" to json and replace it
    # if [message] {
    #     if [message] =~ "\A\{.+\}\z" {
    #     ruby {
    #         code => '
    #                 msgObj = JSON.parse(event.get("message"))
    #                 event.set("message", msgObj)
    #         '
    #         }
    #     }
    # }
}


output {
 stdout {
    # codec => rubydebug
 }
}