Hi
If you have onsite JIRA server and you want to collect its log, you could do just normal log file based integration. Currently this (almost) needs that you have Jira Data Center versions as new server licenses didn't sold anymore and it's out of support from Feb/24.
If you have Atlassian's JIRA cloud version, then just look from splunkbase suitable add-ons for do this. I cannot said which one of those is best option, but there are lot of blogs/articles/videos etc. how you can do it. You should just look those and select correct option after that.
At least some of those also support to integrate JIRA ticketing with splunk. Basically you could create tickets into JIRA based on Splunk Alarms and also update those later on.
r. Ismo
