Floating IP support

[verdurin]

While I did see an error when insufficient floating IPs were allocated to the project, it appears that floating IPs are not in fact associated to instances by default.

Is the intention that these associations are carried out separately inside OpenStack?

[sjpb]

No they are not. You've hit another limitation of our cookiecutter environment vs our actual production configurations. There are some subtleties.

[sjpb]

Currently the cookiecutter TF config has no support for adding FIPs to login nodes. Generally, production sites tend not to need FIPs as login nodes have an interface on a network reachable by users. FIPs are also not available on all clouds so this cannot be a default. However it would be helpful to support optionally defining a pre-existing FIP address as part of the login node definition(s) and attaching this to the node(s).

Note the actual FIP should NOT be defined in the tf config using an openstack_networking_floatingip_v2 resource as this means deleting/recreating the cluster may end up with a different FIP being allocated (and I think there's also some poor/unexpected behaviour wrt whether it is released or not). Instead, the FIP should be manually added to the project and its address added to the tf config, and an openstack_networking_floatingip_associate_v2 resource used to add it to the instance. Note that this still doesn't "protect" the FIP from being attached to by another VM if the cluster is deleted, but that isn't fixable on the openstack level (and isn't a problem if the slurm cluster is the only thing in the project).

[sjpb]

This was added in https://github.com/stackhpc/ansible-slurm-appliance/releases/tag/v1.158. See #572