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

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.

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 }}"

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!

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'] }}"

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/

- 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.

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"

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