How to tweak the json log format in websphere liberty

Question

We have a liberty-based app on IBM Cloud and we'd like to send structured logs to the LogDNA service. Currently, when we set com.ibm.ws.logging.message.format=json it emits the logs in a format like this:

{
  "type": "",
  "host": "",
  "ibm_userDir": "",
  "ibm_serverName": "",
  "message": "",
  "ibm_threadId": "",
  "ibm_datetime": "",
  "module": "",
  "loglevel": "",
  "ibm_sequence": "",
  "ext_thread": ""
}

Instead, LogDNA works best with a format like this:

{
  "line": "This is an awesome log statement",
  "app": "myapp",
  "level": "INFO",
  "env": "production",
  "meta": {
    "customfield": {
      "nestedfield": "nestedvalue"
    }
  }
}

Is there a way to rename the JSON attributes emitted by liberty?

Answer 1

There isn't a built in way to re-map the field names currently -- but we recognize the value of that. There's an open issue at https://github.com/OpenLiberty/open-liberty/issues/6079 . Please add your comments to make sure it covers what you want.

---

UPDATE: As of 19.0.0.10, this feature is now supported!

I can finally get the behavior I expected by setting the logging config in my server.xml to something like this:

<logging traceSpecification="${env.TRACE_SPEC}" traceFileName="stdout" isoDateFormat="true"/>

And setting the following environment variables in my kubernetes deployment:

      containers:
      - env:
        - name: TRACE_SPEC
          value: "*=info"
        - name: WLP_LOGGING_MESSAGE_FORMAT
          value: json
        - name: WLP_LOGGING_MESSAGE_SOURCE
          value: ""
        - name: WLP_LOGGING_CONSOLE_FORMAT
          value: json
        - name: WLP_LOGGING_CONSOLE_LOGLEVEL
          value: info
        - name: WLP_LOGGING_CONSOLE_SOURCE
          value: message,trace,accessLog,ffdc,audit
        - name: WLP_LOGGING_JSON_FIELD_MAPPINGS
          value: loglevel:level,ibm_datetime:timestamp