How to create dynamic variables in ansible - ansible

Question

The real scenario, want to get a resource id of sqs in AWS, which will be returned after the execution of a playbook. So, using this variable in files to configure the application.
Persisting variables from one playbook to another
checking out the documentation, modules like set_fact and register have scope only for that specific host. There are many purpose of using the variables from one host to another.
Alternatives I can think of:
using Command module and echoing the variables to a file. Later, using the variable file using vars section or include.
Setting the env variables and then accessing it but this will be difficult.
So what is the solution?

Answer 1

If you're gathering facts, you can access hostvars via the normal jinja2 + variable lookup:
e.g.
- hosts: serverA.example.org
gather_facts: True
...
tasks:
- set_fact:
taco_tuesday: False
and then, if this has run, on another host:
- hosts: serverB.example.org
...
tasks:
- debug: var="{{ hostvars['serverA.example.org']['ansible_memtotal_mb'] }}"
- debug: var="{{ hostvars['serverA.example.org']['taco_tuesday'] }}"
Keep in mind that if you have multiple Ansible control machines (where you call ansible and ansible-playbook from), you should take advantage of the fact that Ansible can store its facts/variables in a cache (currently Redis and json), that way the control machines are less likely to have different hostvars. With this, you could set your control machines to use a file in a shared folder (which has its risks -- what if two control machines are running on the same host at the same time?), or set/get facts from a Redis server.
For my uses of Amazon data, I prefer to just fetch the resource each time using a tag/metadata lookup. I wrote an Ansible plugin that allows me to do this a little more easily as I prefer this to thinking about hostvars and run ordering (but your mileage may vary).

Answer 2

You can pass variables On The Command Line: http://docs.ansible.com/ansible/playbooks_variables.html#passing-variables-on-the-command-line
ansible-playbook release.yml --extra-vars "version=1.23.45 other_variable=foo"
You can use local connection to run playbook = get variable and apply it to another playbook:
- hosts: 127.0.0.1
connection: local
- shell: ansible-playbook -i ...
register: sqs_id
- shell: ansible-playbook -i ... -e "sqs_id={{sqs_id.stdout}}"
Also delegation might be useful in this scenario:
http://docs.ansible.com/ansible/playbooks_delegation.html#delegation
Also you can store output in the local file and use (http://docs.ansible.com/ansible/playbooks_delegation.html#delegation):
- name: take a sqs id
local_action: command cat ~/sqs_id
PS:
I don't understand why you can't write complex playbook where will be included many roles that will share variables?

Answer 3

You can write "common" variables to a host_vars or group_vars this way all the servers has access to it.
Another way may be to create a custom ansible module/lookup plugin to hide all the boilerplate code and get an easy and flexible access to the variables you need.

Answer 4

I had a similar issue with azure DevOps pipelines.
I created VM:s with terraform, ssh-keys and windows username/password was generated by terraform and stored it in a KeyVault.
So I then needed to query KeyVault before running Ansible on all created VM:s. I ended up using Azure python SDK to get all secrets. I also generate an inventory file and a host_vars folder with a file for each VM.
The actual play-book is now very basic and does the job perfectly. All variables for terraform and ansible is in a json file. And the python script is less than 30 lines.