> ## Documentation Index
> Fetch the complete documentation index at: https://docs.ocient.com/llms.txt
> Use this file to discover all available pages before exploring further.

# LAT Log4J Configuration

export const Ocient = "Ocient®";

export const Log4j2 = "Apache® Log4J 2™";

export const Kafka = "Apache® Kafka®";

<Warning>
  Data Pipelines are now the preferred method for loading data into the {Ocient} System. For details, see [Load Data](/load-data).
</Warning>

The LAT uses {Log4j2} for [logging](https://logging.apache.org/log4j/2.x/). Users can configure their logging setup however they would like. The LAT packages come with example `log4j2.xml` files that can be used directly, or modified by the user. This XML code in the `log4j2.xml` file shows an example configuration.

```xml XML theme={null}
<?xml version="1.0" encoding="UTF-8"?>
<Configuration status="warn" strict="true" monitorInterval="30" packages="biz.paluch.logging.gelf.log4j2">
  <Appenders>
    <RollingRandomAccessFile name="HttpLog" append="true" fileName="logs/http.log" filePattern="logs/http.%d{yyyyMMdd-HH}.%i.log.gz" immediateFlush="true">
      <PatternLayout pattern="%m%n" />
      <Policies>
        <SizeBasedTriggeringPolicy size="100 MB" />
      </Policies>
      <DefaultRolloverStrategy>
        <Delete basePath="logs">
          <IfFileName glob="http.*.log.gz" />
          <IfAccumulatedFileSize exceeds="5 GB" />
        </Delete>
      </DefaultRolloverStrategy>
    </RollingRandomAccessFile>
    <RollingRandomAccessFile name="LATLog" append="true" fileName="logs/lat.log" filePattern="logs/lat.%d{yyyyMMdd-HH}.%i.log.gz" immediateFlush="false">
      <PatternLayout pattern="%d{ISO8601} %-5p [%t] - %m%n" />
      <Policies>
        <SizeBasedTriggeringPolicy size="100 MB" />
      </Policies>
      <DefaultRolloverStrategy>
        <Delete basePath="logs">
          <IfFileName glob="lat.*.log.gz" />
          <IfAccumulatedFileSize exceeds="20 GB" />
        </Delete>
      </DefaultRolloverStrategy>
    </RollingRandomAccessFile>
    <RollingRandomAccessFile name="ErrorLog" append="true" fileName="logs/error.log" filePattern="logs/error.%d{yyyyMMdd-HH}.%i.log.gz" immediateFlush="false">
      <PatternLayout pattern="%m%n" />
      <Policies>
        <SizeBasedTriggeringPolicy size="100 MB" />
      </Policies>
      <DefaultRolloverStrategy fileIndex="nomax">
        <Delete basePath="logs">
          <IfFileName glob="error.*.log.gz" />
          <IfAccumulatedFileSize exceeds="20 GB" />
        </Delete>
      </DefaultRolloverStrategy>
    </RollingRandomAccessFile>
    <!--
    <Gelf name="Graylog" host="udp:graylog-dev" port="12201" version="1.1" extractStackTrace="true">
      <Field name="process_name" literal="lat" />
      <Field name="log_level" pattern="%-5p" />
      <Field name="thread" pattern="%t" />
    </Gelf>
    -->
  </Appenders>
  <Loggers>
    <Logger name="org.apache.kafka" level="info" />
    <Logger name="com.ocient.lat.sink.ocient.Binders.Binder" level="info" />
    <!-- HttpChannel at debug so that jetty preserves the stacktrace when logging uncaught exceptions -->
    <Logger name="org.eclipse.jetty.server.HttpChannel" level="debug" />
    <Logger name="org.eclipse.jetty.server.RequestLog">
      <AppenderRef ref="HttpLog" />
    </Logger>
    <Logger name="com.ocient.lat.sink.file.FileErrorSink" level="info" additivity="false">
      <AppenderRef ref="ErrorLog" />
      <!--
      <AppenderRef ref="Graylog" />
      -->
    </Logger>
    <Logger name="software.amazon.awssdk" level="info" />
    <Logger name="io.netty" level="info" />
    <Root level="info">
      <AppenderRef ref="LATLog" />
      <!--
      <AppenderRef ref="Graylog" />
      -->
    </Root>
  </Loggers>
</Configuration>
```

Relevant Loggers:

* `org.apache.kafka`: {Kafka} logger.
* `com.ocient.lat.sink.ocient.Binders.Binder`: LAT binder logger. Can be verbose, recommended to keep at `info` level.
* `org.eclipse.jetty.server.HttpChannel` and `org.eclipse.jetty.server.RequestLog`: Jetty logs for the HTTP endpoint.
* `com.ocient.lat.Worker`: Main worker logger containing important pipeline logs.

Valid log levels are (in order of least to most verbose):

* `error`
* `warn`
* `info`
* `debug`
* `trace`

Log4j can be configured to log different packages at different levels as shown in the example. Here, the example logs the `com.ocient.streaming.client` package at the trace level, but the remainder of the code is logged at info level.

## Related Links

[Ingest Data with Legacy LAT Reference](/ingest-data-with-legacy-lat-reference)