Support region in OpenStack actions

Launchpad blueprint:

This blueprint intends to support specifying region name for OpenStack actions, so that authorized user could run OpenStack actions within different OpenStack regions in one workflow, which is extremely userful for operators when they want to execute maintainance tasks across different regions within one workflow.

Problem description

Currently, Mistral end user could specify region name or target region name when running OpenStack workflow, which means all the tasks inside the workflow have to be running within that specific region. It’s impossible to run different tasks in different regions.

Use Cases

  • User with credential in region-1 can specify region-2 for the whole workflow (Keystone is shared between different regions).

  • User with credential in region-1 can specify different region in different tasks.

Proposed change

The basic idea is to simplely support ‘action_region’ as an extra input param for actions of configured OpenStack projects..

  1. Add a config option called modules_support_region, the value will be list of module names for which the ‘action_region’ input param will be add to each of its actions. The reason for adding this option is, there may be some OpenStack services (e.g. Keystone) already support region(or similar concept) in action input params, we should not add a param with same meaning, e.g. if Keystone is shared between regions in OpenStack deployment, ‘keystone’ should be excluded from the list.

  2. Insert ‘action_region’ as an optional input param when registering OpenStack actions.


As mentioned in the problem description section, it’s impossible to do multi- region workflows without this feature.

Data model impact

This change doesn’t have to influence the data model.

REST API impact


End user impact

With this change, users could specify region name as action input.

Performance Impact


Deployer impact

When upgrade, deployer should run tools/ script to delete all OpenStack actions and re-create again. ‘action_region’ will be added as input param automatically.



Primary assignee:

Lingxian Kong <>

Work Items

  • Add ‘action_region’ as action input param for modules specified in modules_support_region options. Use ‘action_region’ to construct OpenStack service client.




  • write tests to make sure ‘action_region’ is supported for configured OpenStack modules.

  • write tests to make sure ‘action_region’ is properly used to construct OpenStack service client.