cs_ip_address: add a "tags" parameter to ensure idempotency

[dpassante]

SUMMARY

Due to Cloudstack API limitations, the calls related to IP addresses aren't idempotent.
This implies implementing some complex mechanisms in playbooks that manage public access to Cloudstack deployments.

However, resources tagging can be used to uniquely identify IP addresses.

ISSUE TYPE

• Feature Pull Request

COMPONENT NAME

lib/ansible/modules/cloud/cloudstack/cs_ip_address.py

ANSIBLE VERSION

2.6

ADDITIONAL INFORMATION

[ansibot]

cc @DazWorrall @resmo
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[resmo]

Thanks for this PR: This is a very interesting approach.

I like the general idea to use a unique tag. However, this would be a "special case" in terms of we handle tags in this module differently than anywhere else. That is why I think carefully about it.

Questions I made for myself:

1. Can this break existing setups using tags, if their tags are unique? At some point (first tag) is always unique right?

2. Would it make sense to pre-define a tag key e.g. unique_id just for identify the resource? Just looking for the tag with key unique_id if it exists and value matches?

3. Would it make sense to use this key across all resources supporting tags to avoid a "special case"?

Any thoughts?

[resmo]

needs_info

[dpassante]

Whatever the implementation, I think this shouldn’t break anything as long as the tags are “really unique” across the domain e.g random uuid as value.
If they don't, they could match an existing deployment, but only if it uses an identical key/value pair.

Defining a special tag was my first approach but it seemed an “even more special case” to me.
Anyway, I think it would makes sense if it can be used across all resources supporting tags.
As there is always “special cases”, I guess that could be useful for some setups.

[resmo]

shipit

Thanks again for this helpful contribution!