Description
7.7.0 introduces a new version (11) of the Watcher history index template. This index template may not get installed prior to Watcher writing to the .watcher-history* index. This may happen due to some new behavior that requires the all the nodes to be on 7.7.0 before installing the new version (11) of index template. [1] This likely isn't a concern to most users since the .watcher-history index is esentially a just a log of the watches that have run and is generally only used for troubleshooting and this will likely go unoticed. Further, since Watcher uses a daily index and upgrades usually don't span multiple days the next day's index should have the correct mappings.
This will most likely only be noticed for large watches where the single record of it's execution can exceed the total field of 1000. failure [java.lang.IllegalArgumentException: Limit of total fields [1000] in index [.watcher-history-11-2020.05.13] has been exceeded]
Once an index is created you can not retroactivley apply an index template, so the suggested workaround to this to copy the exiting version (10) and install it as version 11, then delete that day's .watcher-history index. Once the upgrade is complete delete the installed 11 template and Watcher will auto install the real 11 template. Or, you can just ignore the error in the logs for that day, it is pretty harmless since it is effectily a failure to log what happened. However, the error logs can get quite noisy if lots of Watches are running past the 1000 field limit.
[1]
WatcherIndexTemplateRegistry as of #52962.