Setting Up an External Search Tool to Index Confluence
Any web crawler can be configured to index Confluence content. If a login is required to view content that will be indexed, you should create a Confluence user specifically for the search crawler to use. Grant this user view rights to all content you wish to index, but deny that user all delete and administration rights. This ensures that an aggressive crawler will not be able to perform actions that could modify the site.
External applications can also use the search function in the Confluence APIs.