Many sites implement pages where content is driven by the search provider. If there is an issue with search results, rendered pages may be missing some content, and this may not be noticed right away. While Solr does not include built-in monitoring, it does provide a Health Check capability.
The Health Check feature in Solr can be accessed browsing to a URL in the form:
http:// solr-server :7611/solr/ coreNumber /admin/ping
For versions older than 9.2 this URL would be:
http:// solr-server :7602/solr/ coreNumber /admin/ping
Where solr-server is the server where Solr is installed, and coreNumber is the ID for the site you wish to check. You can get the coreNumber for the site being checked by navigating to its workarea then settings > configuration > search > configuration > Solr core name.
The Health Check can be periodically requested by a customer application, which can check the status element and, if the value is other than OK, take an action (for example, send an alert email).