The following procedure describes how to use custom JARs. Some cases may not require completion of every step. For example, indexer tools that support passing JARs as arguments may not require modifying xml files. However, completing all configuration steps helps ensure the custom JARs are used correctly in all cases.

  Note: Search for CDH supports custom plug-in code, but it does not support enabling custom JARs using the Blob Store API and special config API commands. Apache Solr 5.3 implements this functionality so that JARs can be loaded to a special system-level collection and dynamically loaded at run time.

1. Place your custom JAR in the same location on all hosts in your cluster.
2. For all collections where custom JARs will be used, modify solrconfig.xml to include references to the new JAR files.

   These directives can include explicit or relative references and can use wildcards. In the solrconfig.xml file, add <lib> directives to indicate the JAR file locations or <path> directives for specific jar files:

   <lib path="/usr/lib/solr/lib/MyCustom.jar" />

   or

   <lib dir="/usr/lib/solr/lib" />

   or

   <lib dir="../../../myProject/lib" regex=".*\.jar" />

3. For all collections in which custom JARs will be used, reference custom JAR code in the appropriate Solr configuration file. The two configuration files that most commonly reference code in custom JARs are solrconfig.xml and schema.xml.
4. For all collections in which custom JARs will be used, use solrctl to update ZooKeeper's copies of configuration files such as solrconfig.xml and schema.xml:

   solrctl instancedir --update name path

   • name specifies the instancedir associated with the collection using solrctl instancedir --create.
   • path specifies the directory containing the collection's configuration files.
   For example:

   solrctl instancedir --update collection1 $HOME/solr_configs

5. For all collections in which custom JARs will be used, use RELOAD to refresh information:

   http://<hostname>:<port>/solr/admin/collections?action=RELOAD&name=collectionname

   For example:

   http://example.com:8983/solr/admin/collections?action=RELOAD&name=collection1

   When the RELOAD command is issued to any host that hosts a collection, that host sends subcommands to all replicas in the collection. All relevant hosts refresh their information, so this command must be issued once per collection.

6. Ensure that the class path includes the location of the custom JAR file:
   1. For example, if you store the custom JAR file in /opt/myProject/lib/, add that path as a line to the ~/.profile for the Solr user.
   2. Restart the Solr service to reload the PATH variable.
   3. Repeat this process of updating the PATH variable for all hosts.