Compute only stack fail to create

[Steven Hardy]

I should be possible to deploy a stack with only compute nodes, but currently assumptions around the controller as a primary role mean the j2 rendering fails:

(undercloud) [stack@undercloud ~]$ openstack overcloud deploy --templates tripleo-heat-templates --stack compute1 -r compute_only_roles_data.yaml -e compute_only_environment.yaml -e controlplane_endpoint_map.yaml
Started Mistral Workflow tripleo.validations.v1.check_pre_deployment_validations. Execution ID: c0533769-4b1d-4ea1-9678-ce28f8de3dae
Waiting for messages on queue 'tripleo' with no timeout.
Removing the current plan files
Uploading new plan files
Started Mistral Workflow tripleo.plan_management.v1.update_deployment_plan. Execution ID: 58ecb2a6-8a72-4aa5-b538-243caa69a089
Error rendering template common/post-upgrade.yaml : list object has no element 0
Exception updating plan: Error rendering template common/post-upgrade.yaml : list object has no element 0

We should allow compute only roles where upgrade is disabled.

[Bogdan Dobrelya (bogdando)]

looks like a dup of https://bugs.launchpad.net/tripleo/+bug/1734703

[Steven Hardy (shardy)]

> looks like a dup of https://bugs.launchpad.net/tripleo/+bug/1734703

No I don't think so - this bug is about deploying with no roles that have upgrade enabled, it's a different problem, with a different fix - see https://review.openstack.org/#/c/521927/

Unfortunately I forgot to tag that for this bug, apoligies