In your index template, it shows below which seems incorrect
rollover_alias should be example sonicwall instead of having a -* inside
Also your logstash conf.d index => should point to your rollover_alias instead of "sonicwall-%{+YYYY.MM.dd}"
If you wanted to add date to your index, you can take a look at this post or read up on date math
This document helps me alot when I'm configuring ILM
Hope this can help you!