Solr is an application that runs on it's own, independent of Drupal. So before we can integrate our Drupal site with the Solr server we first need to install Solr and get it running. In this tutorial we'll walk through the requirements for installing Solr and then look at a quick and easy way to get it running on our localhost for development purposes. This setup is best for when you're working on a site locally, but have it hosted elsewhere and someone else is managing your Solr install for you.
The basic process is to download the Solr application, unpack it somewhere on your localhost, and then run the start.jar file that comes with the example application:
java -jar start.jar. To ensure it's working you can connect to the Solr web UI on your localhost at http://localhost:8983/solr/.
Note: When using Solr with Drupal and the Search API module we currently need to use the most recent 4.x version of Solr, despite the fact that there is a 5.x version that just came out. At the time these tutorials where recorded the Search API module had not yet been updated to work with Solr >= 5.x. The general installation instructions for localhost development however are not likely to change much at all between Solr 4 and 5 so even if you're using Solr 5 this should still be relevant information.
By the end of this tutorial you should be able to run Solr on your localhost and verify that it is working.