Adding better support for groups via the metadata.groups attribute

[jackspirou]

This pull request adds better support for groups, via the metadata.groups attribute and fixes #16

[vasiliyb]

@jackspirou I've tried compiling from your fork, with no avail:

go get github.com/jackspirou/terraform-inventory
cd src/gitub.com/jackspirou/terraform-inventory
go build

./terraform-inventory --list still shows the hosts separate

[jackspirou]

@vasiliyb can you send me an example file your using? Do you have a metadata.groups attribute listed?

[vasiliyb]

@jackspirou email sent, thank you! I dont see metadata.groups in --list output

[adammck]

Hello! Thanks very much for your patch. However, I also can't seem to get it to work. None of the resources in my state files seem to include a meta.groups attribute. Can you provide an example?

[jackspirou]

Hi @vasiliyb and @adammck, sorry for the delay in responding. So the reason I submitted this was because our team needed something that Ansible groups could easily pickup. This PR takes the approach of adding a metadata.groups attribute (which I hear is quite popular with other tools) to the .tfstate file. This can be done by including the following code for a resource in main.tf

resource "openstack_compute_instance_v2" "hive" {
  count = "${lookup(var.instances, var.env)}"
  security_groups = ["default", "HTTP"]
  name = "${var.env}-hive-${count.index}"
  region = "${var.region}"
  image_name = "${module.settings.images}"
  flavor_name = "${lookup(var.flavor, var.env)}"
  key_pair = "${module.settings.key_pair}"
  floating_ip = "${lookup(var.static_address, var.env)}"
  network {
    name = "${module.settings.private_net}"
  }
  metadata {
    groups = "web,api,hive"
  }
}

After using terraform apply with the example above, running terraform-inventory --list <filepath> would result in:

{"api":["10.65.82.170"],"hive":["10.65.82.170"],"web":["10.65.82.170"]}

So values like "metadata.groups": "mongosc,mongos,mongoc", might produce groups along side the current --list outputt:

{
  "mongoc":["10.10.10.101","10.10.10.102","10.10.10.103"],
  "mongos":["10.10.10.101","10.10.10.102","10.10.10.103"],
  "mongosc":["10.10.10.101","10.10.10.102","10.10.10.103"],
  "server.0":["10.10.10.101"],
  "server.1":["10.10.10.102"],
  "server.2":["10.10.10.103"]
}

Let me know your thoughts and if this still makes sense given PR #22 or if we can consider #16 fixed.

[jackspirou]

After taking a look at PR #22 I think it accomplishes much of this, but from what I understand it doesn't allow for multiple resources to one group, or multiple resources to multiple groups. So for example, you might have a shared Ansible bootstrap play to set default configuration on all servers belonging to the HTTP Ansible group.

Again all feedback welcome.

[adammck]

Thanks for getting back to me, @jackspirou. You're right that #22 doesn't provide arbitrary group names, which is something I'd very much like to add. I wasn't familiar with the metadata attribute, because (as far as I can tell), it's only supported by the OpenStack provider. But most other providers have their own mechanism (e.g. AWS's instance tags) for this sort of thing.

I refactored master a bit already (to make this sort of thing simpler in future), and will try to get this merged shortly. Thanks very much for the patch!

[jackspirou]

This PR has conflicts. Closing.