[doc] Redeploy cinder/compute nodes if new controller added

[OpenStack Infra]

https://review.openstack.org/132549
commit 1d3982f606b5d0d0cba78b52a5806abee6a97918
Author: Dima Shulyak <email address hidden>
Date: Mon Nov 3 13:37:37 2014 +0200

    Redeploy cinder/compute nodes if new controller added

    Addition of new controller affects cluster messaging,
    particularly cinder/computes nodes which is reliant on
    rabbitmq_hosts settings

    In current orchestration model - the only way to
    fix configuration on nodes is to redeploy them.
    Configuration will be applied from /etc/astute.yaml and
    it is not enough to simply add additional PostDeployment
    method in astute

    Introduced additional setting for roles_metadata:
    - update_required
      should store list of roles that dependends on this role

    On deployment stage:
    - make update_required list for the whole cluster
    - select ready nodes without pending_roles and deploy them

    No migration added to keep behaviour on old clusters as it is

    DocImpact
    Closes-Bug: 1368445

    Change-Id: I1735a8b06531018b1240726f5faa4f7ce6e6a631

[Bogdan Dobrelya (bogdando)]

There is a separate section in ops guide about adding new nodes. This change description should land there.

[Sheena Conant (sheena-conant)]

I think this should be added to User Guide for 8.0 - any reason why it should go to 6.1 specifically? Is this still a valid workflow?

[Alexander Adamov (aadamov)]

I'd rather put it KB (or deprecated OpsGuide) - as it solves the issue when adding a new controller

[Fuel Devops McRobotson (fuel-devops-robot)]

Fix proposed to branch: master
Change author: Svetlana Karslioglu <email address hidden>
Review: https://review.fuel-infra.org/16926

[Fuel Devops McRobotson (fuel-devops-robot)]

Change abandoned by Svetlana Karslioglu <email address hidden> on branch: master
Review: https://review.fuel-infra.org/16926
Reason: scheduled for improvement for 9.0