Let EC2 inventory script use r53 hostname as ansible_host

[stpierre]

SUMMARY

This lets the user SSH to the r53 hostname, which, depending on domain
topology, may be easier to manage SSH configs for.

For instance, our hosts all have *.compute-1.amazonaws.com as their public hostname, but a sensible CNAME in route53. Using that CNAME makes the configurations in ~/.ssh/config work, even across subdomains (which are expressed through the r53 CNAME records).

ISSUE TYPE

• Feature Pull Request

COMPONENT NAME

EC2 dynamic inventory script

ANSIBLE VERSION

ansible 2.8.0.dev0 (ec2-inventory-r53-hostname-as-dest 49908c42c6) last updated 2018/11/09 13:39:59 (GMT -500)
  config file = None
  configured module search path = [u'/home/stpierre/.ansible/plugins/modules', u'/usr/share/ansible/plugins/modules']
  ansible python module location = /home/stpierre/devel/ansible/lib/ansible
  executable location = /home/stpierre/devel/ansible/bin/ansible
  python version = 2.7.15 (default, Oct 15 2018, 15:24:06) [GCC 8.1.1 20180712 (Red Hat 8.1.1-5)]

ADDITIONAL INFORMATION

[ansibot]

Hi @stpierre, thank you for submitting this pull-request!

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[ansibot]

cc @ryansb @s-hertel @willthames
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[s-hertel]

You can set hostvars like ansible_host using the constructed inventory plugin's compose option as well, though I'm not sure if that is useful in this case. You can inspect your hostvars with ansible-inventory -i contrib/inventory/ec2.py --list to help determine that.

[stpierre]

Looks like that doesn't help in this case; the r53 hostname isn't included in any variables except as the inventory hostname, and

compose:
    ansible_hostname: inventory_hostname

...doesn't work. (Nor does any other iteration with s/hostname/host/.)