Mistral is a code name for workflow service in OpenStack. Most processes consist of multiple distinct interconnected steps that need to be executed in a specific order in a distributed environment. With Mistral, the user can describe such process as a set of tasks and its task relation, then; upload such description to Mistral so that it takes care of the correct execution order. Mistral also provides flexible task scheduling so that we can run a process according to a specified schedule instead of running it immediately.

For example, a user can use the Mistral service to schedule a task to execute a bash script on specified virtual machines, and then post the output response of the first task as the input for the next task in the workflow through the REST API call, to execute another bash script in other virtual machines. It is essential that several tasks can be combined in a single workflow and run in an on-schedule time. Mistral will take care of their workflow execution.