I am trying to configure the slack notification alert app for multiple slack channels. There seems to be only one option for a webhook URL but we need to be able to configure multiple webhook URLs to be able to post to multiple channels in the same organization/workspace... Anyone have a solution to this?
There is a second slack notification app within the Splunk apps available: https://splunkbase.splunk.com/app/3525/#/details
It seems to be possible using this app to configure a Slack Webhook URL within the trigger actions for each alert. So you should be able to define this on alert level and send to multiple channel depending on the webhook you're using.