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

# Configure Fusion Logging in Fusion 4.0

export const LwTemplate = ({title = "Key questions to get you started", icon = "sparkles", cta = "Powered by Agent Studio", linkHref = "https://lucidworks.com/demo/?utm_source=docs&utm_medium=referral&utm_campaign=docs_cta_ai"}) => {
  const [isLoaded, setIsLoaded] = useState(false);
  useEffect(() => {
    const timer = setTimeout(() => {
      setIsLoaded(true);
    }, 500);
    return () => clearTimeout(timer);
  }, []);
  return <div className="lw-template-container">
      <Card title={title} icon={icon}>
        {isLoaded && <span dangerouslySetInnerHTML={{
    __html: `<lw-template id="a029c1a9-28be-427e-b0e1-5d918920246a"></lw-template
            >`
  }} />}
        <Link href={linkHref} className="agent-studio-link text-left text-gray-600 gap-2 dark:text-gray-400 text-sm font-medium flex flex-row items-center hover:text-primary dark:hover:text-primary-light group-hover:text-primary group-hover:dark:text-primary-light">Powered by Lucidworks Agent Studio</Link>
      </Card>
    </div>;
};

[localhost link]: http://localhost:3000/docs/4/fusion-server/reference/fusion-configure-logging-40

[mintlify link]: https://doc.lucidworks.com/docs/4/fusion-server/reference/fusion-configure-logging-40

[old doc.lw link]: https://doc.lucidworks.com/fusion-server/4.2/671

Fusion uses the [Apache Log4j 2](http://logging.apache.org/log4j/2.x/manual/index.html) logging framework with Jetty to log each of the Fusion components.

<LwTemplate />

Logging is configured with an XML configuration file named `log4j2.xml`. Log levels, frequencies, and log rotation policy can be configured by changing these configuration files:

|                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |
| --------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| API service           | `https://FUSION_HOST:FUSION_PORT/conf/api-log4j2.xml`                                                                                                                                                                                                                                                                                                                                                                                                                                        |
| Connectors            | `https://FUSION_HOST:FUSION_PORT/conf/connectors-classic-log4j2.xml`  `https://FUSION_HOST:FUSION_PORT/conf/connectors-rpc-agent-log4j2.xml`  `https://FUSION_HOST:FUSION_PORT/conf/connectors-rpc-log4j2.xml`                                                                                                                                                                                                                                                                               |
| Solr                  | `https://FUSION_HOST:FUSION_PORT/conf/solr-log4j2.xml`                                                                                                                                                                                                                                                                                                                                                                                                                                       |
| Spark                 | `https://FUSION_HOST:FUSION_PORT/conf/spark-driver-launcher-log4j2.xml`  `https://FUSION_HOST:FUSION_PORT/conf/spark-driver-log4j2.xml`  `https://FUSION_HOST:FUSION_PORT/conf/spark-driver-scripted-log4j2.xml`  `https://FUSION_HOST:FUSION_PORT/conf/spark-master-agent-log4j2.xml`  `https://FUSION_HOST:FUSION_PORT/conf/spark-master-log4j2.xml`  `https://FUSION_HOST:FUSION_PORT/conf/spark-worker-agent-log4j2.xml`  `https://FUSION_HOST:FUSION_PORT/conf/spark-worker-log4j2.xml` |
| SQL                   | `https://FUSION_HOST:FUSION_PORT/conf/sql-agent-log4j2.xml`  `https://FUSION_HOST:FUSION_PORT/conf/sql-log4j2.xml`                                                                                                                                                                                                                                                                                                                                                                           |
| UI                    | `https://FUSION_HOST:FUSION_PORT/conf/admin-ui-log4j2.xml`                                                                                                                                                                                                                                                                                                                                                                                                                                   |
| ZooKeeper             | `https://FUSION_HOST:FUSION_PORT/conf/zk-log4j2.xml`                                                                                                                                                                                                                                                                                                                                                                                                                                         |
| Other Fusion services | `https://FUSION_HOST:FUSION_PORT/conf/proxy-log4j2.xml`                                                                                                                                                                                                                                                                                                                                                                                                                                      |

The [Log4j2 Configuration](http://logging.apache.org/log4j/2.x/manual/configuration.html) guide provides documentation and examples of all logging configuration options.