fuel-devops not trackig dependencies between network devices

[Sergey Yudin]

https://github.com/openstack/fuel-devops/blob/master/devops/models/group.py#L45

this code return network objs in random order, meanwhile we may have dependencies between them, e.g.

public network may be bridged with public-raw and we must ensure public raw will be started first.

Workaround is to order networks by ifaces and first bring up ifaces with most dependecies like

- return self.l2networkdevice_set.filter(**kwargs)
+ devs = self.l2networkdevice_set.filter(**kwargs)
+ return sorted(devs, key=lambda dev: len(dev.interfaces), reverse=True)

but proper solution is to build tree and return first ifaces wo dependencies.

In attachment yaml which will help to reproduce issue. It will fail because public will be started before public-raw.

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/319258
Committed: https://git.openstack.org/cgit/openstack/fuel-devops/commit/?id=83bfa424a2113cd897b9b73cdd36ebfee4fe9ee1
Submitter: Jenkins
Branch: master

commit 83bfa424a2113cd897b9b73cdd36ebfee4fe9ee1
Author: Anton Studenov <email address hidden>
Date: Mon Jul 4 17:55:31 2016 +0300

    Proper ordering for objects loaded from templates

    - Use OrderedDict for loading objects from yaml template.
    - Load objects from db with the order they were saved.
      It guarantees that objects will be defined in the same order
      that they appear in template file.
    - added id field to Group
    - added unit tests for yaml_template_load

    Related-Bug: #1591750
    Change-Id: I2cafa1fbe156b1ddbd5546d06938e65c9b6bf4bf

[Sergey Yudin (tsipa740)]

I'd say commit "Proper ordering for objects loaded from templates" correct and valid, but not sufficient.
Since devops being used by other components like a f-qa with this approach we will have to change everything what relies on devops templates to use ordered hashes to get expected behavior. I still think since we may have a hierarchy of interfaces we should build a three with dependencies and start/define ifaces following those dependencies.