Ansible Handle Multiple Elements in Hash - ansible

Question

I'm trying to load a list of hosts in my playbook to provision a KVM. I need to key this off of the hosts.yml because another playbook is going to take the hosts and connect to them once they're up.
This my hosts.yml:
kvm:
hosts:
kvm01
dcos:
dcos-bootstrap:
hosts:
dcos-bootstrap
vars:
lv_size: "10g"
dcos-masters:
hosts:
dcos-master-1
vars:
lv_size: "50g"
dcos-agents:
hosts:
dcos-agent-1
dcos-agent-2
vars:
lv_size: "50g"
So on a single KVM I run this playbook to create the logical volumes for each of the Virtual Machines corresponding to the dcos hosts:
---
- hosts: kvm
tasks:
- name: Get a list of vm's to create
include_vars:
file: "../hosts.yml"
- name: Verify the host list
debug: var=dcos
when: dcos is defined
- name: Provision Volume Groups
lvol:
vg: vg01
lv: "{{ item.value.hosts }}"
size: "{{ item.value.vars.lv_size }}"
with_dict: "{{ dcos }}"
This works fine until you include more than one host for a group. I've tried other loops but I'm not sure how to continue. How can I iterate over the hash while working on each host in a group?

Answer 1

I'm new to Ansible so I really wasn't sure how to accomplish what I wanted. I initially tried to parse the hosts file myself, not knowing that Ansible does this for me. Now I know...
All of the host and group data is stored in host_vars and groups. All I needed to do what use this like so:
vars:
dcoshosts: "{{ groups['dcos'] }}"
tasks:
- name: List groups
debug:
msg: "{{ groups }}"
- name: Get All DCOS hosts
debug:
msg: "Host: {{ item }}"
with_items:
- "{{ dcoshosts }}"
- name: Provision Volume Groups
lvol:
vg: vg01
lv: "{{ item }}"
size: "{{ hostvars[item].lv_size }}"
with_items: "{{ dcoshosts }}"
I ended up using a hosts.ini file instead of yaml because the ini worked and the yaml didn't. Here it is to complete the picture:
[dcos-masters]
dcos-master-1
dcos-master-2
[dcos-masters:vars]
lv_size="50g"
[dcos-agents]
dcos-agent-1
dcos-agent-2
[dcos-agents:vars]
lv_size="50g"
[dcos-bootstraps]
dcos-bootstrap
[dcos-bootstraps:vars]
lv_size="10g"
[dcos:children]
dcos-masters
dcos-agents
dcos-bootstraps
Thanks to everybody for the help and pushing me to my solution :)

Answer 2

You try to reinvent what Ansible provides already.
This is the Ansbile way of life:
Define your hosts and groups in an inventory file dcos.ini:
[dcos-bootstraps]
dcos-bootstrap
[dcos-masters]
dcos-master-1
[dcos-agents]
dcos-agent-1
dcos-agent-2
[dcos:children]
dcos-bootstraps
dcos-masters
dcos-agents
Then you customize the group parameters in group variables.
Bootstrap parameters in groups_vars/dcos-bootstraps.yml:
---
lv_size: 10g
Masters parameters in group_vars/dcos-masters.yml:
---
lv_size: 50g
Agents parameters in group_vars/dcos-agents.yml:
---
lv_size: 50g
And your playbooks becomes quite simple:
---
- hosts: dcos
tasks:
- name: Provision Volume Groups
lvol:
vg: vg01
lv: "{{ inventory_hostname }}"
size: "{{ lv_size }}"
When you run this each host gets its lv_size parameter based on the group membership of the host.

Answer 3

First of all, you I suspect you have incorrect data.
If you want your hosts to be a list, you should make it so:
kvm:
hosts:
kvm01
dcos:
dcos-bootstrap:
hosts:
- dcos-bootstrap
vars:
lv_size: "10g"
dcos-masters:
hosts:
- dcos-master-1
vars:
lv_size: "50g"
dcos-agents:
hosts:
- dcos-agent-1
- dcos-agent-2
vars:
lv_size: "50g"
Note the hyphens.
And to your question: if you are not going to use "group" names in your loop (like dcos-bootstrap, etc.), you can use with_subelements:
- name: Provision Volume Groups
lvol:
vg: vg01
lv: "{{ item.1 }}"
size: "{{ item.0.vars.lv_size }}"
with_subelements:
- "{{ dcos }}"
- hosts