terraform/juju/bosh are purpose-build for app and infra deployments.

StackStorm is a generic automation platform with no . One can use it to run arbitrary chain of actions on events. As such, it is used in auto-remediation & automating runbooks. We internally use it for variety of things like irc-to-slack relay, zombie ec2 vm periodic clean-up, ChatOps-ing JIRA, etc.

Some folks do run complex continuos deployment pipelines and blue/green deployments on StackStorm. Would be good if they can comment here.