Avoidable(?) error message after changing log format to JSON?

[psheichelberg]

I have changed the log format of my kafka.kafka.strimzi.io with this configuration:

spec:
  kafka:
    logging:
      type: inline
      loggers:
        appender.console.layout.type: JsonTemplateLayout
        appender.console.layout.eventTemplate: […] # omited, see https://github.com/apache/logging-log4j2/blob/rel/2.25.3/log4j-layout-template-json/src/main/resources/LogstashJsonEventLayoutV1.json 

This works fine (except for a few log lines at startup that are probably printed by kafka_run.sh.

But now I have an error message in my logs:

2026-02-17T08:30:44.370423732Z main ERROR JsonTemplateLayout contains an invalid element or attribute "pattern"

I suspect the reason is that the appender.console.layout.pattern is still present:

apiVersion: v1
kind: ConfigMap
data:
  cluster.id: gbZ8TcatQ6SYatEUQp4LCg
  log4j2.properties: |
    # Do not change this generated file. Logging can be configured in the corresponding Kubernetes resource.
    name=KafkaConfig
    appender.console.type=Console
    appender.console.name=STDOUT
    appender.console.layout.type=JsonTemplateLayout
    appender.console.layout.pattern=%d{yyyy-MM-dd HH:mm:ss} %-5p [%t] %c{1}:%L - %m%n
    […]
    appender.console.layout.eventTemplate=[…]

Is there any way to unset/remove the appender.console.layout.pattern line? I would like to not have ERROR messages in my logs when they are not actually errors. 😅

Thank you in advance!

[psheichelberg]

I tried nil, null and "" but it did not help:

spec:
  kafka:
    logging:
      loggers:
        appender.console.layout.pattern: nil
        appender.console.layout.pattern: null
        appender.console.layout.pattern: ""

[scholzj]

The inline configuration is designed for simple changes such as log levels etc. For more complex changes such as using custom layout, you should use the external logging configuration.

[psheichelberg]

Thanks, that worked!

[…]
spec:
  kafka:
    logging:
      type: external
      valueFrom:
        configMapKeyRef:
          name: kafka-logging
          key: log4j2.properties
[…]
---
apiVersion: v1
kind: ConfigMap
metadata:
  name: kafka-logging
data:
  log4j2.properties: |-
[…]

[dawchotryg]

@psheichelberg could you please share the full configmap kafka-logging? Beside this do you need to add additional jars to the strimzi image to get it working? If so which and where? I'm trying with jsonevent-layout-1.7.jar but it doesn't seem work.

[psheichelberg]

I don't remember the details anymore but I guess using jars did not work for me either, because this is my log4j2.properties file:

name = COConfig
monitorInterval = 30
appender.console.type = Console
appender.console.name = STDOUT
appender.console.layout.type = JsonTemplateLayout
# Event template based on https://github.com/apache/logging-log4j2/blob/rel/2.25.3/log4j-layout-template-json/src/main/resources/LogstashJsonEventLayoutV1.json
# curl -fLSs https://github.com/apache/logging-log4j2/raw/refs/heads/2.x/log4j-layout-template-json/src/main/resources/LogstashJsonEventLayoutV1.json | jq -cM 'del(."@version",.source_host)'
appender.console.layout.eventTemplate = {"mdc":{"$resolver":"mdc"},"exception":{"exception_class":{"$resolver":"exception","field":"className"},"exception_message":{"$resolver":"exception","field":"message","stringified":true},"stacktrace":{"$resolver":"exception","field":"stackTrace","stackTrace":{"stringified":true}}},"line_number":{"$resolver":"source","field":"lineNumber"},"class":{"$resolver":"source","field":"className"},"message":{"$resolver":"message","stringified":true},"thread_name":{"$resolver":"thread","field":"name"},"@timestamp":{"$resolver":"timestamp"},"level":{"$resolver":"level","field":"name"},"file":{"$resolver":"source","field":"fileName"},"method":{"$resolver":"source","field":"methodName"},"logger_name":{"$resolver":"logger","field":"name"}}
rootLogger.level = INFO
rootLogger.appenderRefs = stdout
rootLogger.appenderRef.console.ref = STDOUT
logger.kafka.name = org.apache.kafka
logger.kafka.level = WARN
logger.netty.name = io.netty
logger.netty.level = INFO

[dawchotryg]

Thanks! I was able to configure it without any external jars. Thanks for help.