use AWS inventory plugin (instead of deprecated ec2.py inventory 'script')

[lhoss]

A PR that was long overdue, since I've used the AWS inventory plugin now since most of 2019.

Notes

• Inventory plugins were introduced since ansible v2.4, and since then are the recommended way to configure dynamic (cloud) inventories
• Docs: https://docs.ansible.com/ansible/latest/plugins/inventory.html
• Added advantages:
  • no more need to package (and git manage) lengthy scripts
  • smaller config, more flexible
  • This Repository's License can be harmonized to only "Apache License", once we have replaced all other Cloud inventory scripts by the respective inventory plugin
• the ansible.cfg inventory section I added, thx to the auto entry, should work for any cloud plugin (in recent ansible versions), but if you still run with older ansible versions (as 2.5.x) you might need to explicitly add the plugin to make it work (in this case aws_ec2). At least I had experienced trouble when I used the AWS plugin with ansible <v2.7.x

[seanorama]

Will existing users of the old AWS approach need to change anything or be impacted by the change?

[lhoss]

Will existing users of the old AWS approach need to change anything or be impacted by the change?

Hi Sean

• Indeed this change will impact users with existing old (AWS)approach cfg, due to the change in
  add_nodes_aws.yml
  • maybe would need to branch into a new major version (from the other side, not sure how many people still interested in this role.. with CDP being the future)
• (If this change is accepted) ideally we should also migrate the other cloud providers