Do YAML inventory plugins support inheritance?

[Guy Knights]

I'm experimenting with the new AWS_EC2 plugin and have been wondering if there's a way to streamline the file as we have separate inventory folders for dev, demo and prod. Is there a way to do something like and 'include' for the bulk of the YAML file content and just have the different environment filters in each inventory's specific file? eg. something like this:

Central file (central.aws_ec2.yml):

plugin: aws_ec2
regions:
  - us-east-1
  - us-east-1
  - us-west-1
  - us-west-2
  - ap-southeast-2
filters:
  instance-state-name: running
strict_permissions: False
hostnames:
  - tag:Name
  - private-ip-address
strict: False
keyed_groups:
  - prefix: ''
    separator: ''
    key: tags.Type

Demo inventory file (demo.aws_ec2.yml):

include: central.aws_ec2.yml
filters:
  tag:Environment: demo

Thanks,

Guy

[Ryan Brown]

Guy,

It looks like the specific case you have of filtering based on a given tag can be solved without having several inventories.

If you use the `constructed` part of inventory plugins, https://docs.ansible.com/ansible/2.7/plugins/inventory/constructed.html which lets you do all kinds of advanced grouping based on properties such as tags.

Also, here's an issue you can watch which is related to allowing importing w/ vars. It doesn't extend to config, but would be the same principal.

[Guy Knights]

Thanks Ryan, I did some tests and got this working using the constructed plugin.

One issue I ran into though is that the inventory plugin files appear to be loaded alphabetically, so if the constructed inventory filename is alphabetically 'smaller', the constructed inventory file will be loaded first, and the host inventory may not yet be populated by the other inventory files. I found an issue logged about this: https://github.com/ansible/ansible/issues/31405. I've got around this in the meantime by prefixing the name of my inventory file with 'z_'. It seems to me that Ansible's behaviour should be to always load constructed inventory files last since they rely purely on the output of other inventory plugins.

Anyway, just noting that extra bit of info here in case anyone stumbles upon this thread. Thanks again for your help!

Kind regards,

Guy

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Guy Knights • Senior Systems Engineer c: 778-996-2687p: 778-379-5120