Compute V2: Don't fail when disassociating floating IP from the instance when it is already not associated.

[rnurgaliyev]

According to Compute API documentation, an attempt to remove floating IP association from an instance may fail with 409, when floating IP address was not associated with this instance initially.

This patch enables "create_before_destroy" lifecycle in openstack_compute_floatingip_associate_v2 resource. When used together with an instance, whose lifecycle also has create_before_destroy, this patch will remove downtime in a rolling update - floating IP address will be reassociated only when the new instance is completely provisioned.

Without this patch, setting create_before_destroy in lifecycle of openstack_compute_floatingip_associate_v2 will cause terraform to fail. New VM will be provisioned before deleting the old one, then new floating ip address association will be created, re-assigning same floating IP address from the existing resource, but on the next step terraform will fail while trying to delete old association since it is not there anymore in OpenStack. However, there is no need to fail - resource is actually deleted, and consequent "terraform plan" will show no changes.

This issue is discussed in here: https://github.com/terraform-providers/terraform-provider-openstack/issues/439

[theopenlab-ci]

Build succeeded.

• terraform-provider-openstack-unittest : SUCCESS in 3m 10s
• terraform-provider-openstack-acceptance-test : SUCCESS in 2h 14m 39s

[jtopjian]

LGTM! Thank you so much for working on this.

[jtopjian]

I think it would be hard to write an acceptance test for this. I have tested this offline and can confirm it works.