We have changed the configuration (props.conf) on a Universal Forwarder so that it will now use the correct sourcetype for a couple of log files.
How do I go about getting
a) the forwarder to "resend" the events in those files with the new correct source type
b) getting the indexer to re-index those events.
Alternatively, is there a way to change the source type for those events at the indexer?
c) You cannot modify the data once it is indexed.
b) The indexer will happily re-index duplicates, nothing to do there. However, if you want to get rid of the old events you can either empty the corresponding index (and delete every other event in that index along the way!) or mark them as deleted with the delete command (won't reclaim space).
a) You need to empty the fish bucket on the forwarder to get it to re-read files that have already been read. It'll then re-read everything on the forwarder, make sure you don't get unwanted duplicates from other sources.