20 Common Use Cases for Automating Network Device Configuration with Ansible

In the previous article on system administration and automated deployment, we introduced how to use Ansible for automated system management. In this article, we focus specifically on automating network device configuration. As the number of network devices continues to grow, manual configuration management becomes increasingly impractical—making Ansible’s ability to streamline this process especially valuable.

Introduction to Ansible

Ansible is a powerful IT automation tool designed to simplify application deployment, configuration management, and task automation. It employs an agentless architecture and uses YAML to define configuration files (called playbooks), making configurations intuitive and easy to understand.

Network Device Modules

Ansible provides several modules dedicated to managing network devices, including:

• ios_config: For configuring Cisco IOS devices
• nxos_config: For configuring Cisco NX-OS devices
• eos_config: For configuring Arista EOS devices
• netconf: For managing devices via the NETCONF protocol

Each module offers common capabilities—such as uploading configurations, checking device state, and rolling back to previous configurations—tailored to its respective platform.

Environment Setup

Before using Ansible to configure network devices, ensure your environment is properly configured. You’ll need to install Ansible, and your target network devices must support SSH or another supported management protocol.

Install Ansible using the following command:

pip install ansible

Example: Configuring a Cisco IOS Device

Below is a simple example demonstrating how to configure a Cisco IOS device with Ansible.

1. Create an Inventory File

First, create an inventory file listing the network devices you wish to manage:

[routers]
router1 ansible_host=192.0.2.1 ansible_user=admin ansible_password=your_password

2. Write a Playbook

Next, write an Ansible playbook to configure a device interface. Here's an example playbook (config_ios.yml):

---
- name: Configure Cisco IOS devices
  hosts: routers
  gather_facts: no
  tasks:
    - name: Ensure interface is configured
      ios_config:
        lines:
          - description Configured by Ansible
          - ip address 192.0.2.2 255.255.255.0
          - no shutdown
        parents: interface GigabitEthernet0/1

3. Run the Playbook

Execute the playbook with the following command:

ansible-playbook -i inventory config_ios.yml

Upon execution, Ansible connects to router1 and applies the specified configuration.

Checking Device Status

After configuring network devices, you may want to verify their operational status. Below is an example playbook (check_interfaces.yml) that retrieves interface status information:

---
- name: Check interface status
  hosts: routers
  gather_facts: no
  tasks:
    - name: Check interface status
      ios_command:
        commands:
          - show ip interface brief
      register: interface_status

    - name: Show interface status
      debug:
        var: interface_status.stdout_lines

Run it with:

ansible-playbook -i inventory check_interfaces.yml

This displays the interface status directly in the console output.

Summary

Through the above examples, we’ve explored the fundamentals of using Ansible for automated network device configuration. This approach not only improves operational efficiency but also significantly reduces the risk of human error. In the next section, we’ll explore cross-platform application deployment, continuing our journey into Ansible’s vast capabilities.

This section has covered core usage patterns and practical examples of Ansible in network device management. For deeper exploration, consult the official documentation or community resources.