Ansible - read inventory hosts and variables to group_vars/all file - ansible

Question

I have a dummy doubt that keeps me stuck for a long time. I have a very banal inventory file with hosts and variables:
[lb]
10.112.84.122
[tomcat]
10.112.84.124
[jboss5]
10.112.84.122
...
[tests:children]
lb
tomcat
jboss5
[default:children]
tests
[tests:vars]
data_base_user=NETWIN-4.3
data_base_password=NETWIN
data_base_encrypted_password=
data_base_host=10.112.69.48
data_base_port=1521
data_base_service=ssdenwdb
data_base_url=jdbc:oracle:thin:#10.112.69.48:1521/ssdenwdb
The problem is that I need to access all these hosts and variables, in the inventory file, from the group_vars/all file.
I've tried the following manners to access the host IP:
{{ lb }}
"{{ hostvars[lb] }}"
"{{ hostvars['lb'] }}"
{{ hostvars[lb] }}
To access a host variable I tried:
"{{ hostvars[tests].['data_base_host'] }}"
All of them are wrong!!! Can anyone help me find out the best practice to access hosts and variables, not from a playbook but from a variables file?
EDIT:
Ok. Let's clarify.
Problem: Use a host declared in the inventory file in a variable file, let's say: group_vars/all.
Example: I have a DB host with IP:10.112.83.37.
Inventory file:
[db]
10.112.83.37
In the group:vars/all file I want to use that IP to build a variable.
group_vars/all file:
data_base_url=jdbc:oracle:thin:#{{ db }}:1521/ssdenwdb
In a template I use the variable built in the group_vars/all file.
Template file:
oracle_url = {{ data_base_url }}
The problem is that the {{ db }} variable in the group_vars/all file is not replaced by the DB host IP. The user can only edit the inventory file.

Answer 1

- name: host
debug: msg="{{ item }}"
with_items:
- "{{ groups['tests'] }}"
This piece of code will give the message:
'10.112.84.122'
'10.112.84.124'
as groups['tests'] basically return a list of unique ip addresses ['10.112.84.122','10.112.84.124'] whereas groups['tomcat'][0] returns 10.112.84.124.

Answer 2

If you want to programmatically access the inventory entries to include them in a task for example. You can refer to it like this:
{{ hostvars.tomcat }}
This returns you a structure with all variables related with that host. If you want just an IP address (or hostname), you can refer to it like this:
{{ hostvars.jboss5.ansible_ssh_host }}
Here is a list of variables which you can refer to: click. Moreover, you can declare a variable and set it with for example result of some step in a playbook.
- name: Change owner and group of some file
file: path=/tmp/my-file owner=new-owner group=new-group
register: chown_result
Then if you play this step on tomcat, you can access it from jboss5 like this:
- name: Print out the result of chown
debug: msg="{{ hostvars.tomcat.chown_result }}"

Answer 3

Just in case if the problem is still there,
You can refer to ansible inventory through ‘hostvars’, ‘group_names’, and ‘groups’ ansible variables.
Example:
To be able to get ip addresses of all servers within group "mygroup", use the below construction:
- debug: msg="{{ hostvars[item]['ansible_eth0']['ipv4']['address'] }}"
with_items:
- "{{ groups['mygroup'] }}"

Answer 4

Considering your previous example:
inventory file:
[db]
10.112.83.37
group_vars/all
data_base_url=jdbc:oracle:thin:#{{ db }}:1521/ssdenwdb
template file:
oracle_url = {{ data_base_url }}
You might want to replace your group_vars/all with
data_base_url="jdbc:oracle:thin:#{{ groups['db'][0] }}:1521/ssdenwdb"

Answer 5

Yes the example by nixlike works very well.
Inventory:
[docker-host]
myhost1 user=barbara
myhost2 user=heather
playbook:
---
- hosts: localhost
connection: local
tasks:
- name: loop debug inventory hostnames
debug:
msg: "the docker host is {{ item }}"
with_inventory_hostnames: docker-host
- name: loop debug items
debug:
msg: "the docker host is {{ hostvars[item]['user'] }}"
with_items: "{{ groups['docker-host'] }}"
output:
ansible-playbook ansible/tests/vars-test-local.yml
PLAY [localhost]
TASK [setup]
******************************************************************* ok: [localhost]
TASK [loop debug inventory hostnames]
****************************************** ok: [localhost] => (item=myhost2) => {
"item": "myhost2",
"msg": "the docker host is myhost2" } ok: [localhost] => (item=myhost1) => {
"item": "myhost1",
"msg": "the docker host is myhost1" }
TASK [loop debug items]
******************************************************** ok: [localhost] => (item=myhost1) => {
"item": "myhost1",
"msg": "the docker host is barbara" } ok: [localhost] => (item=myhost2) => {
"item": "myhost2",
"msg": "the docker host is heather" }
PLAY RECAP
********************************************************************* localhost : ok=3 changed=0 unreachable=0
failed=0
thanks!

Answer 6

If you want to refer one host define under /etc/ansible/host in a task or role, the bellow link might help:
https://www.middlewareinventory.com/blog/ansible-get-ip-address/

Answer 7

If you want to have your vars in files under group_vars, just move them here. Vars can be in the inventory ([group:vars] section) but also (and foremost) in files under group_vars or hosts_vars.
For instance, with your example above, you can move your vars for group tests in the file group_vars/tests :
Inventory file :
[lb]
10.112.84.122
[tomcat]
10.112.84.124
[jboss5]
10.112.84.122
...
[tests:children]
lb
tomcat
jboss5
[default:children]
tests
group_vars/tests file :
data_base_user=NETWIN-4.3
data_base_password=NETWIN
data_base_encrypted_password=
data_base_host=10.112.69.48
data_base_port=1521
data_base_service=ssdenwdb
data_base_url=jdbc:oracle:thin:#10.112.69.48:1521/ssdenwdb