Solr is a “popular, blazing fast open source enterprise search platform from the Apache Lucene project”. Drupal search has traditionally been less then adequate. Using Solr to index and search you Drupal site is therefore quite helpful.

To start, download the Solr package (link) and the Solr drupal module (link). the current standard distribution is Solr 1.4 and Drupal 6.
Unarchive the tar files in a location that is reachable from your server.

We will assume that tomcat is installed in /opt/tomcat

In the Solr package there is an example application. That is the Solr application we are going to use. If you can write your own, you probably don’t need this tutorial.

Step 1:
Copy the example application, found in the solr package under example/webapps to the tomecat webapps folder which should be /opt/tomcat/webapps. when copying the file rename it to something other the solr. this will enable you to have multiplie solr installations running under one Tomcat container. We will assume the app is renamed new_solr_inst. If you are in the tomcat root folder the command should like like this:
cp /path/to/solr/package/apache-solr-1.4.0/apache-solr-1.4.0/example/webapps/solr.war webapps/new_solr_inst.war

Tomcat will pick up the war file and open it automatically after a restart.

Step 2:
In the tomcat root folder create a folder to hold your Solr configuration and data.
mkdir new_solr_inst
Copy the example app configuration into that folder
cp -R /path/to/solr/package/apache-solr-1.4.0/apache-solr-1.4.0/example/solr/* new_solr_inst

Step 3:
You need to replace the original schema.xml and solrconfig.xml with the ones provided by the drupal module. Copy these two files to your Solr configuration folder. Assuming you are currently at the tomcat root folder
cp /path/to/solr/module/schema.xml new_solr_inst/conf
cp /path/to/solr/module/solrconfig.xml new_solr_inst/conf
The Solr app is now ready for use.

Step 4:
The last step is needed to inform Tomcat about the app and its settings. Go to conf/Catalina/localhost and create the file new_solr_inst.xml. In that file fill the following content:

Step 5:
You need to restart tomcat
/opt/tomcat/bin/shutdown.sh
/opt/tomcat/bin/startup.sh
And your Solr should be running. There are three tests we can use to check everything went well.

• Tomcat has opened the war file. There is now a folder new_solr_inst in the webapps folder of Tomcat.
• Solr has made a data directory in the Solr home folder (that is /opt/tomcat/new_solr_inst)
• In your browser go to the Solr app http://domain:tomcat_port/new_solr_inst and you should see a welcome screen

If all is well you are ready to combine this Solr installation with your Drupal

Step 6:
Activate the Apache-Solr module and go to the Solr module settings page admin/settings/apachesolr
Assuming tomcat and drupal are running on the same server fill in localhost as the host name, fill in the port tomcat is running on and solr path should be your app name in the tomcat webapps folder. In our case is it new_solr_inst.

Save the settings. Drupal should inform you that a connection is made with Solr

Notes

• It is not nessecary to put the app configuration in the Tomcat root folder. you can probably (though I have not tested this) place it anywhere you want. you do need to make sure that the environment tag in the Tomact configuration file (the one in the conf/Catalina/localhost folder) is pointing to the right place.
• If you make changes to the schema you may need to dump all the indices Solr has made. you can do this via the Drupal admin interface for the Solr module.