Ansible Inventory Management for Network Automation: A Beginner’s Guide

Network automation is becoming increasingly important in today’s complex and dynamic network environments. One of the most powerful tools for network automation is Ansible, an open-source platform that simplifies and accelerates network tasks through its inventory feature. In this blog post, we will explore how to use Ansible inventory management to simplify and automate network tasks, and how it can be used to improve network reliability and repeatability.

Ansible Inventory Management

Ansible’s inventory feature allows you to store all of the runtime variables for a given playbook as facts. This means that you can easily access and manipulate the values of these variables in your playbooks, making it easier to perform tasks such as data gathering and validation. Ansible supports two formats for an on-controller inventory: conf (Windows-like) and YAML (Linux-like). We will be using the YAML format in this example.

Using the Inventory Feature

To use the inventory feature, you first need to update your Ansible inventory. This can be done using the API method, which requires multiple new variables. Once you have updated your inventory, you can run extremely simple playbooks to gather data. Ansible’s inventory feature enables you to scale per node without any additional code, making it easy to manage large networks with many nodes.

The Power of Idempotency

One of the key benefits of using Ansible for network automation is its idempotency. This means that running repeated executions of a playbook is safe, as Ansible will only make changes if they do not already exist. This makes it easy to use Ansible to check for the presence of certain services or configuration items, and then take action based on the results.

Example: Checking for Cisco Fabric Services

Recently, Cisco disclosed a vulnerability with Cisco Fabric Services, which affects many network environments. To fix this vulnerability, you can use Ansible to check for the presence of the service and disable it if it is running. Here’s an example playbook that demonstrates how to do this:

“`yaml

—

– name: Check for Cisco Fabric Services

hosts: all

become: true

tasks:

– name: Check for Fabric Services

nxos_facts:

facts:

inventory: cml

register: fabric_services

debug:

var: fabric_services

“`

In this example, we are using the `nxos_facts` module to gather information about the network nodes. The `inventory` parameter is set to `cml`, which tells Ansible to use the inventory feature to retrieve the node information. The `register` parameter is used to store the results of the `nxos_facts` module in a variable called `fabric_services`. Finally, we are using the `debug` module to print the contents of the `fabric_services` variable to the console.

Conclusion

Ansible inventory management is a powerful tool for network automation that simplifies and accelerates network tasks. By using Ansible’s inventory feature, you can easily access and manipulate the values of runtime variables, making it easier to perform tasks such as data gathering and validation. Additionally, Ansible’s idempotency makes it safe to run repeated executions of playbooks, allowing you to easily check for the presence of certain services or configuration items and take action based on the results. We hope this blog post has provided a helpful introduction to using Ansible inventory management for network automation.