Mistral Workflows should validate their inputs

[Dougal Matthews]

Many of the workflows accept inputs, but if they are changed from the defaults and don't match what is expected they can fail in obscure ways.

We could work around this with a custom action that validates inputs. It would then be used at the start of workflows to validate the inputs as the first task. It could look something like this...

tasks:
  validate_inputs:
    action: tripleo.validate_inputs
    input:
      task_context: <% $ %>
      types:
        queue_name: string
        container: plan_name
        timeout: integer
    on-success: original_workflow_first_action

This would verify that the queue_name, container and timeout inputs. The "types" (string, plan_name and integer) would need to be known names in the action which would map to a validating function/regex.

The action could look something like this...

validators = {
    "plan_name": validating_function,
    ...
}

class ValidateInputs(base.Action):
    def __input__(self, task_context, types):
        self.task_context = task_context
        self.types = types
    def run(self, context):

        for name, type in self.types.items():
            value = self.task_context.get(name)
            assert validators[type](value)

[Dougal Matthews (d0ugal)]

I think it makes more sense to try and solve this more generally in Mistral.