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Question

Parsing Syslog With Nested JSON

  • December 15, 2025
  • 0 replies
  • 6 views

Rmoss
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Hi,

How do I parse out “data_user_agent” in the below the nested JSON ? The log is Syslog with a JSON object:

<190>Dec 9 19:55:40 test-local-primary test_audit:

{

"actor_ip": "1.1.1.1,

"action": "login",

"created_at": [removed by moderator] ,

"data": {

"user_agent": "Mozilla/5.0 (Macintosh Intel Mac OS X 10.15 rv:145.0) Gecko/20100101 Firefox/145.0",

"method": "POST",

"@timestamp": [removed by moderator] ,

"category_type": "Authentication",

}

}

My parser is as follows but it doesn’t pick up anything for the “data_user_agent” field.

filter {

mutate {

replace => {

"data_user_agent" => ""

}

}

mutate {replace => {"event.idm.read_only_udm.metadata.event_type" => "GENERIC_EVENT"}}

if [data_user_agent] != "" {

mutate {

replace => {

"data_user_agent.key" => "data_user_agent"

"data_user_agent.value.string_value" => "%{data_user_agent}"

}

merge => {

"event.idm.read_only_udm.additional.fields" => "data_user_agent"

}

}

}

if [data_user_agent] != "" {

mutate {

replace => {

"event.idm.read_only_udm.network.http.user_agent" => "%{data_user_agent}"

}

}

}

statedump {}

mutate {

merge => {

"@output" => "event"

}

}

}

STATEDUMP:

Internal State (label=):

{
"@collectionTimestamp": {
"nanos": 0,
"seconds": [removed by moderator]
},
"@createTimestamp": {
"nanos": 0,
"seconds": [removed by moderator]
},
"@enableCbnForLoop": true,
"@onErrorCount": 0,
"@output": [],
"@timestamp": {
"nanos": 0,
"seconds": [removed by moderator]
},
"@timezone": "",
"data_user_agent": "",
"event": {
"idm": {
"read_only_udm": {
"metadata": {
"event_type": "GENERIC_EVENT"
}
}
}
},
"hostname": "test-local-primary",
"message": "\u003c190\u003eDec 9 19:55:40 test-local-primary test_audit: \n{\n \"actor_ip\": \"1.1.1.1\",\n \"action\": \"login\",\n \"created_at\": [removed by moderator] ,\n \"data\": {\n \"user_agent\": \"Mozilla/5.0 (Macintosh Intel Mac OS X 10.15 rv:145.0) Gecko/20100101 Firefox/145.0\",\n \"method\": \"POST\",\n \"category_type\": \"Authentication\"\n }\n}",
"time": "Dec 9 19:55:40"
}