Document how swap to structured logging

[xphir]

Summary

Please add official guidance (and example configuration) for turning on structured, machine-readable logging in Kafka-UI. JSON logs are easier to ingest and query in modern observability stacks.

Note:

There is probably a better way to do this if the logback-spring.xml did not exist, as the default spring-boot framework has some good inbuilt default that could be controlled just via config.

You could likely even maintain current behaviour defaulting logging.pattern.console to %black(%d{ISO8601}) %highlight(%-5level) [%blue(%t)] %yellow(%c{1}): %msg%n%throwable

Motivation / use-case

• Teams using tools such as Loki, Elastic, Datadog, or CloudWatch Logs benefit from consistent JSON output.
• Clear documentation would remove trial-and-error for newcomers and promote best-practice adoption.

Example working setup

Below is a minimal configuration that produces JSON logs at INFO level. It can be included as an example or starting point in the docs.

Dockerfile

FROM ghcr.io/kafbat/kafka-ui:v1.2.0

# Copy the custom config file
COPY config.yaml /opt/config.yaml

# Copy the custom Logback file
COPY logback-spring.xml /opt/logback-spring.xml

config.yaml

...
logging:
  config: /opt/logback-spring.xml

  structured:
    format:
      console: logstash

  level:
    org.springframework.security: INFO
    io.kafbat.ui.service.rbac: INFO
...

logback-spring.xml

<?xml version="1.0" encoding="UTF-8"?>
<configuration>

    <appender name="CONSOLE" class="ch.qos.logback.core.ConsoleAppender">
      <filter class="ch.qos.logback.classic.filter.ThresholdFilter">
        <level>${CONSOLE_LOG_THRESHOLD}</level>
      </filter>
      <encoder class="org.springframework.boot.logging.logback.StructuredLogEncoder">
        <format>${CONSOLE_LOG_STRUCTURED_FORMAT}</format>
        <charset>${CONSOLE_LOG_CHARSET}</charset>
      </encoder>
    </appender>

    <root level="INFO">
      <appender-ref ref="CONSOLE"/>
    </root>

</configuration>

References

• Spring Boot logging guide (structured logging): https://docs.spring.io/spring-boot/3.4-SNAPSHOT/reference/features/logging.html#features.logging.structured
• Default structured-console-appender example: https://github.com/spring-projects/spring-boot/blob/3.4.x/spring-boot-project/spring-boot/src/main/resources/org/springframework/boot/logging/logback/structured-console-appender.xml
• Default spring boot logback file https://github.com/spring-projects/spring-boot/blob/3.4.x/spring-boot-project/spring-boot/src/main/resources/org/springframework/boot/logging/logback/defaults.xml
• Kafka UI logback file https://github.com/kafbat/kafka-ui/blob/main/api/src/main/resources/logback-spring.xml