This epic tracks the end-to-end adoption of a 2+ multi-cell 17.1 Nova control plane into the new installer.

NOTE: multi-cell with different networks/subdomains to be a follow-on feature, after this basic multi cell with a common network is complete.

Stories will be filed within this epic to cover the adoption of the controller services and the compute nodes.

This epic is not expected to be completed in a single quarter but the stories it contains will be scoped to a single quarter.

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This implies that the source OpenStack has 3 tripleo heat stack

A central stack with no computes nodes hosting cell-0 and an empty cell-1
a dedicated cell-2 stack with computes
a second cell-3 stack with computes

This topology would requiet at least 1 undercloud, 1 controller, 2 cell conductors and 2 comptue nodes one for each of cell-2 and cell-3

in tripleo proper this might force 1 undercloud + 3 ha overcloud controller + 6 conductor 3 per real cell due to triple ha requirements.

there is nothing in nova that would require 13 nodes for this topology
in devstack we can do this with 3 nodes total so one of the challenges is how to test this in ci without need a very large number of nodes.

thus, the HW footprint may be reduced to a 5 nodes for dev and adoption CI needs:

• undercloud
• non HA controller in overcloud stack
• cell controller in cell 1 stack
• cell compute in cell 1 stack
• cell controller in cell 2 stack, combined with a cell compute (single-node overcloud is supported in OSP officially)