I have several indices that have a prefix, let's say ABCD-123-* . Is there a way to monitor/watch each individual index that starts with the aforementioned prefix and alert when the index reach a particular size. For instance have a watcher that will trigger an email when an index that starts with ABCD-123-* hits 40GB. I can't find any info for how to accomplish this.
you could use the (monitoring feature)[https://www.elastic.co/guide/en/elasticsearch/reference/6.6/configuring-monitoring.html] and query those indices in a watch.
Outside of watcher, the index lifecycle management feature might be interesting for you as well, depending on what you plan to do with that above information and if automation can help maybe.