Ansible Inventory: teoría + ejercicios resueltos

Introducción

Guía de lectura sobre inventarios:

Resumen: el formato del inventario puede ser en INI o YAML principalmente, y dependiendo de si se usa uno u otro, la forma de definir variables, grupos de hosts, etc cambia. El inventario por defecto se encuentra en /etc/ansible/hosts. Las variables que se pueden usar estan en Connecting to hosts: behavioral inventory parameters

The simplest inventory is a single file with a list of hosts and groups. The default location for this file is /etc/ansible/hosts. You can specify a different inventory file at the command line using the -i <path> option or in configuration using inventory.

Guía para construir el archivo inventario: How to build your inventory

Even if you do not define any groups in your inventory file, Ansible creates two default groups: all and ungrouped. The all group contains every host. The ungrouped group contains all hosts that don’t have another group aside from all. Every host will always belong to at least 2 groups (all and ungrouped or all and some other group)

Example of inventory in YAML format:

leafs:
  hosts:
    leaf01:
      ansible_host: 192.0.2.100
    leaf02:
      ansible_host: 192.0.2.110

spines:
  hosts:
    spine01:
      ansible_host: 192.0.2.120
    spine02:
      ansible_host: 192.0.2.130

network:
  children:
    leafs:
    spines:

webservers:
  hosts:
    webserver01:
      ansible_host: 192.0.2.140
    webserver02:
      ansible_host: 192.0.2.150

datacenter:
  children:
    network:
    webservers:

Example of inventory in INI format

[atlanta]
host1
host2

[atlanta:vars]
ntp_server=ntp.atlanta.example.com
proxy=proxy.atlanta.example.com

Ejercicios

We have a sample inventory file with 3 servers listed. Add a fourth server by the name server4.company.com

# Sample Inventory File

server1.company.com
server2.company.com
server3.company.com

Solución

# Sample Inventory File

server1.company.com
server2.company.com
server3.company.com
server4.company.com

We have added aliases named web1, web2 and web3 for the first three servers. Update server4 to have an alias db1

# Sample Inventory File

web1 ansible_host=server1.company.com
web2 ansible_host=server2.company.com
web3 ansible_host=server3.company.com
server4.company.com

Solución:

# Sample Inventory File

web1 ansible_host=server1.company.com
web2 ansible_host=server2.company.com
web3 ansible_host=server3.company.com
db1 ansible_host=server4.company.com

The web servers are linux, but the db server is windows. Add additional parameters in each line to add ansible_connection, ansible_user and password. Use the below table for information about credentials.

Alias	Host	Connection	User	Password
web1	server1.company.com	SSH	root	Password123!
web2	server2.company.com	SSH	root	Password123!
web3	server3.company.com	SSH	root	Password123!
db1	server4.company.com	Windows	administrator	Password123!

Note: For linux use ansible_ssh_pass and for windows use ansible_password. Connector for windows is winrm

# Sample Inventory File

web1 ansible_host=server1.company.com
web2 ansible_host=server2.company.com
web3 ansible_host=server3.company.com
db1 ansible_host=server4.company.com

Solución:

# Sample Inventory File

# Web Servers
web1 ansible_host=server1.company.com ansible_connection=ssh ansible_user=root ansible_ssh_pass=Password123!
web2 ansible_host=server2.company.com ansible_connection=ssh ansible_user=root ansible_ssh_pass=Password123!
web3 ansible_host=server3.company.com ansible_connection=ssh ansible_user=root ansible_ssh_pass=Password123!

# Database Servers
db1 ansible_host=server4.company.com ansible_connection=winrm ansible_user=administrator ansible_password=Password123!

We have created a group for web servers. Similarly create a group for database servers named db_servers and add db1 server to it.

# Sample Inventory File

# Web Servers
web1 ansible_host=server1.company.com ansible_connection=ssh ansible_user=root ansible_ssh_pass=Password123!
web2 ansible_host=server2.company.com ansible_connection=ssh ansible_user=root ansible_ssh_pass=Password123!
web3 ansible_host=server3.company.com ansible_connection=ssh ansible_user=root ansible_ssh_pass=Password123!

# Database Servers
db1 ansible_host=server4.company.com ansible_connection=winrm ansible_user=administrator ansible_password=Password123!

[web_servers]
web1
web2
web3

Solución:

# Sample Inventory File

# Web Servers
web1 ansible_host=server1.company.com ansible_connection=ssh ansible_user=root ansible_ssh_pass=Password123!
web2 ansible_host=server2.company.com ansible_connection=ssh ansible_user=root ansible_ssh_pass=Password123!
web3 ansible_host=server3.company.com ansible_connection=ssh ansible_user=root ansible_ssh_pass=Password123!

# Database Servers
db1 ansible_host=server4.company.com ansible_connection=winrm ansible_user=administrator ansible_password=Password123!


[web_servers]
web1
web2
web3

[db_servers]
db1

Let us now create a group of groups. Create a new group called all_servers and add the previously created groups web_servers and db_servers to it.

Note: Syntax:
[parent_group:children]
child_group1
child_group2

# Sample Inventory File

# Web Servers
web1 ansible_host=server1.company.com ansible_connection=ssh ansible_user=root ansible_ssh_pass=Password123!
web2 ansible_host=server2.company.com ansible_connection=ssh ansible_user=root ansible_ssh_pass=Password123!
web3 ansible_host=server3.company.com ansible_connection=ssh ansible_user=root ansible_ssh_pass=Password123!

# Database Servers
db1 ansible_host=server4.company.com ansible_connection=winrm ansible_user=administrator ansible_password=Password123!


[web_servers]
web1
web2
web3

[db_servers]
db1

Solución:

# Sample Inventory File

# Web Servers
web1 ansible_host=server1.company.com ansible_connection=ssh ansible_user=root ansible_ssh_pass=Password123!
web2 ansible_host=server2.company.com ansible_connection=ssh ansible_user=root ansible_ssh_pass=Password123!
web3 ansible_host=server3.company.com ansible_connection=ssh ansible_user=root ansible_ssh_pass=Password123!

# Database Servers
db1 ansible_host=server4.company.com ansible_connection=winrm ansible_user=administrator ansible_password=Password123!


[web_servers]
web1
web2
web3

[db_servers]
db1

[all_servers:children]
web_servers
db_servers

Try and represent the data given in the below table in Ansible Inventory format

Server Alias	Server Name	OS	User	Password
sql_db1	sql01.xyz.com	Linux	root	Lin$Pass
sql_db2	sql02.xyz.com	Linux	root	Lin$Pass
web_node1	web01.xyz.com	Win	administrator	Win$Pass
web_node2	web02.xyz.com	Win	administrator	Win$Pass
web_node3	web03.xyz.com	Win	administrator	Win$Pass

Group the servers together based on this table

Group	Members
db_nodes	sql_db1, sql_db2
web_nodes	web_node1, web_node2, web_node3
boston_nodes	sql_db1, web_node1
dallas_nodes	sql_db2, web_node2, web_node3
us_nodes	boston_nodes, dallas_nodes

Solución:

# Sample Inventory File

# Web Servers
web_node1 ansible_host=web01.xyz.com ansible_connection=winrm ansible_user=administrator ansible_password=Win$Pass
web_node2 ansible_host=web02.xyz.com ansible_connection=winrm ansible_user=administrator ansible_password=Win$Pass
web_node3 ansible_host=web03.xyz.com ansible_connection=winrm ansible_user=administrator ansible_password=Win$Pass

# DB Servers
sql_db1 ansible_host=sql01.xyz.com ansible_connection=ssh ansible_user=root ansible_ssh_pass=Lin$Pass
sql_db2 ansible_host=sql02.xyz.com ansible_connection=ssh ansible_user=root ansible_ssh_pass=Lin$Pass

# Groups
[db_nodes]
sql_db1
sql_db2

[web_nodes]
web_node1
web_node2
web_node3

[boston_nodes]
sql_db1
web_node1

[dallas_nodes]
sql_db2
web_node2
web_node3

[us_nodes:children]
boston_nodes
dallas_nodes