http://e26whn2524322mkxb3cbyk27ev2ihhq2biz35hty7gzgsyrwrygq27yd.onion/posts/documentation/linux/745-allowing-your-internal-search-engine-to-index-gitlab-issues-commits-and-wiki-pages.html
Almost more importantly that being able to index your issues though, is being able to index your wiki pages. As bad as it might be not to be able to search for project issues, the idea of a wiki not being trivially indexable is a million times worse, compounded only by the possibility of a user finding a wiki page, but not being able to view it because of Javascript issues.