EXPERIMENTAL: test lifecycle ignore image changes via variable

[sjpb]

When a compute group has compute_init_enable set/non-empty:

• Using the ansible variable image_id templated out using the compute group tf var of the same name, into the TF-templated ansible inventory for that compute group.

  • This means that ansible will have image_id for each compute node, and the compute_init:export.yml task will write that out into the /exports/cluster/hostvars.

• Add a lifecycle block to the openstack_compute_instance_v2 resource so that subsequent changes to the tf cluster_image variable for that compute group don’t actually result in a change via tf plan/apply. This is done with the meta-argument "ignore_changes"

  • In practice this isn't possible due to meta-arguments (e.g. lifecycle and its contents) only taking static values, so duplication of the openstack_compute_instance_v2 is necessary with some gated condition on which is used.

[bertiethorpe]

LGTM

[sjpb]

Only done to demo a workaround.