Open Stack

Hi all,

Today I had a productive hallway discussion with jtomasek and
stevebaker re $subject, so I wanted to elaborate here for the benefit
of those folks not present.  Hopefully we can get feedback on the
ideas and see if it makes sense to continue and work on some patches:

The problem under discussion is how do we run pre-deployment workflows
(such as those integrated recently to calculate derived parameters,
and in future perhaps also those which download container images etc),
and in particular how do we make these discoverable via the UI
(including any input parameters).

The idea we came up with has two parts:

1. Add a new optional section to roles_data for services that require
pre-deploy workflows

E.g something like this:

     pre_deploy_workflows:
        - derive_params:
              workflow_name:
tripleo.derive_params_formulas.v1.dpdk_derive_params
              inputs:
                  ...

This would allow us to associate a specific mistral workflow with a
given service template, and also work around the fact that currently
mistral inputs don't have any schema (only key/value input) as we
could encode the required type and any constraints in the inputs block
(clearly this could be removed in future should typed parameters
become available in mistral).

2. Add a new workflow that calculates the enabled services and returns
all pre_deploy_workflows

This would take all enabled environments, then use heat to validate
the configuration and return the merged resource registry (which will
require https://review.openstack.org/#/c/509760/), then we would
iterate over all enabled services in the registry and extract a given
roles_data key (e.g pre_deploy_workflows)

The result of the workflow would be a list of all pre_deploy_workflows
for all enabled services, which the UI could then use to run the
workflows as part of the pre-deploy process.

If this makes sense I can go ahead and push some patches so we can
iterate on the implementation?

Thanks,

Steve