Scenario:
We have these 6 servers in hosts file:
[web_servers]
10.200.0.2
10.200.0.3
[db_servers]
10.200.0.6
10.200.0.7
[dns_servers]
10.200.0.8
10.200.0.9
We want Bind9 to be installed only on dns_servers
We want MariaDB to be installed only on db_servers
We want Nginx to be installed only on web_servers
We want user 'notadmin' to be created on all servers
For this example I will use Debian based servers.
The hosts file (see above) is copied in current working directory
First we create ansible role named "using-ansible-group-vars-example:
$ ansible-galaxy init using-group-vars-example
Then we create file playbook-using-group-vars-example.yml in the current working directory with the following content:
---
- name: How to use group_vars example
hosts: all
remote_user: admin
become: yes
roles:
- ./using-group-vars-example
Note: all remote hosts should be configure according Ansible documentation for this to work (ssh-copy-id and user "admin" in the /etc/sudoers with access to sudo with no password).
Then we create group_vars directory again in the current working directory:
$ mkdir group_vars
Now we have directory structure like this:
Create the following files inside group_vars/ directory with the names of the server groups from our hosts file
group_vars/db_servers.yml
---
install_mariadb: "true"
create_user: "true"
group_vars/dns_servers.yml
---
create_user: "true"
install_dns: "true"
group_vars/web_servers.yml
---
install_nginx: "true"
create_user: "true"
Content of the using-group-vars-example/defaults/main.yml should be this:
---
# defaults file for using-group-vars-example
# we must initialize these otherwise it will pop an error
create_user: none
install_nginx: none
install_mariadb: none
install_dns: none
Content of the using-group-vars-example/tasks/main.yml should be this:
---
# tasks file for using-group-vars-example
- name: install nginx
include_tasks: nginx.yml
when: install_nginx == "true"
- name: create user
include_tasks: user.yml
when: create_user == "true"
- name: install dns server
include_tasks: dns.yml
when: install_dns == "true"
- name: install mariadb server
include_tasks: db.yml
when: install_mariadb == "true"
Now we create 4 more files inside the using-group-vars-example/tasks/ as follow:
using-group-vars-example/tasks/dns.yml
---
- name: Install BIND9
apt:
name: bind9 bind9-utils
state: present
update_cache: yes
using-group-vars-example/tasks/db.yml
---
- name: Install MariaDB server
apt:
name: mariadb-server mariadb-server-core
state: present
update_cache: yes
using-group-vars-example/tasks/nginx.yml
---
- name: Update the repository cache and update package "nginx"
apt:
name: nginx
state: present
update_cache: yes
using-group-vars-example/tasks/user.yml
---
- name: Add the user 'notadmin'
user:
name: notadmin
state: present
comment: notadmin user for testing purposes
createhome: yes
home: /home/notadmin
These will be included only when declared in group_vars/ yml files
Now the final structure should look like this:
now we run this from the . directory like this:
$ ansible-playbook playbook-using-group-vars-example.yml -i hosts
