Workflow UUID support in Mistral REST API

https://blueprints.launchpad.net/mistral/+spec/use-workflow-id-in-rest-api

Problem description

Currently, we identify a workflow by its name, of course, the workflow name is unique within a tenant’s scope. However, when we use ‘public’ workflows or we want to get benifits from workflow sharing feature[1], we may see more than one workflows with the same name (you can see a related bug which has been fixed here[2]). Even worse, users will never see other ‘same-name’ workflows when performing mistral workflow-get <name> command, since it always returns the first one.

Look at almost all other projects, they always use UUID as globally unique resource identifier, especially in the REST API, the resource name is a string that can be duplicated throughout the whole system, and may be changed frequently as the time goes by.

So, I propose we use UUID as the workflow global unique identifier in the REST API. What’s more, we can consider using UUID for other resources after that.

Use Cases

  • As a user, I want to see the definition of a public scope workflow, whose name is the same with one of my private workflows or another public workflow.

  • As a user or application developer, I want to send REST API to Mistral with resource UUID contained, rather than resource name.

Proposed change

We need to support workflow UUID as a parameter of pecan WorkflowsController related methods(GET, PUT, DELETE), we still support workflow name for backward compatibility, the magic will be happened in the db api layer. At the meanwhile, workflow UUID needs to be exposed to end users, using which users could do operations they want.

Things will be a little complicated for PUT method. Before, when we want to update a workflow definition, Mistral only accepts URL like http://localhost:8989/v2/workflows and the new workflow definition content as request body, which means workflow name is an identifier when updating workflow definition, and can’t be changed. In order to support UUID, a new parameter with an appropriate default value will be added to PUT method, with the UUID, workflow name can be changed. In addition, when updating a workflow with UUID provided, only one workflow definition could be contained in request body.

Since UUID is so important right now, users should see that both via REST API or Mistral client, a good news is, UUID has already be supported from both server side and client side[3].

Changes should also be made for db interface, operations should be supported based on UUID.

Alternatives

Without the UUID support in REST API, those problems mentioned in the first section can’t be solved totally.

Data model impact

None

REST API impact

All the REST API requests for workflow resource will support UUID, the request and response body are the same with before, the only exception to this is PUT HTTP method.

When updating a workflow with UUID provided, only one workflow definition could be contained in request body.

End user impact

It’s strongly recommended that users use UUID in URL of HTTP request or in the command line.

Performance Impact

None

Deployer impact

None

Implementation

Assignee(s)

Primary assignee:

kong <anlin.kong@gmail.com>

Work Items

  • Add UUID support for GET, PUT, DELETE mothod of workflow REST API.

Dependencies

None

Testing

  • Test the UUID support in REST API and/or Mistral client side.