Getting Started with Network Automation Using Ansible

Network automation is no longer optional—it's essential for modern infrastructure. In this guide, we'll explore how Ansible can transform your network operations.

Why Ansible for Network Automation?

Ansible offers several advantages for network engineers:

• Agentless - No software to install on network devices
• YAML-based - Human-readable configuration
• Idempotent - Safe to run multiple times
• Vendor-agnostic - Works with Cisco, Juniper, Arista, and more

Prerequisites

Before we begin, ensure you have:

1. Python 3.8+ installed
2. Ansible 2.9 or later
3. Access to network devices (physical or virtual)

Installation

# Install Ansible via pip
pip install ansible

# Verify installation
ansible --version

Your First Network Playbook

Let's create a simple playbook to gather facts from Cisco devices:

---
# save as gather_facts.yml
- name: Gather Network Facts
  hosts: all
  gather_facts: false
  connection: network_cli
  
  vars:
    ansible_network_os: ios
  
  tasks:
    - name: Get device facts
      ios_facts:
        gather_subset: all
    
    - name: Display hostname
      debug:
        var: ansible_hostname
    
    - name: Display interfaces
      debug:
        var: ansible_net_interfaces

Inventory Configuration

Create your inventory file:

# save as inventory
[switches]
192.168.1.1
192.168.1.2

[routers]
192.168.1.100

[all:vars]
ansible_user=admin
ansible_ssh_pass=your_password
ansible_become_pass=enable_password

Running the Playbook

# Dry run first
ansible-playbook gather_facts.yml --check

# Actually run it
ansible-playbook gather_facts.yml

Real-World Example: Backup Configuration

Here's a more practical playbook that backs up running configurations:

---
- name: Network Configuration Backup
  hosts: all
  gather_facts: false
  connection: network_cli
  
  vars:
    backup_dir: /path/to/backups
  
  tasks:
    - name: Create backup directory
      file:
        path: "{{ backup_dir }}"
        state: directory
        mode: '0755'
    
    - name: Fetch running config
      ios_config:
        backup: yes
        backup_options:
          filename: "{{ inventory_hostname }}-{{ ansible_date_time.date }}.cfg"
          dir_path: "{{ backup_dir }}"

Best Practices

1. Use Ansible Vault for Secrets

# Create encrypted vault file
ansible-vault create group_vars/all/vault.yml

# Edit vault
ansible-vault edit group_vars/all/vault.yml

2. Organize with Group Variables

inventory/
group_vars/
  all/
    vault.yml      # Secrets
    global.yml     # Global settings
  switches/
    switches.yml   # Switch-specific
  routers/
    routers.yml    # Router-specific

3. Use Dynamic Inventory

For cloud environments, use dynamic inventory plugins:

# aws_ec2.yml
plugin: amazon.aws.aws_ec2
regions:
  - us-east-1
filters:
  tag:Environment: production

Common Modules Reference

| Module | Purpose | |--------|---------| | ios_config | Configure Cisco IOS | | ios_facts | Gather IOS facts | | eos_config | Configure Arista EOS | | junos_config | Configure Juniper Junos | | netconf_config | Configure via NETCONF |

Next Steps

1. Explore NAPALM - Network Automation with Python and LLMs
2. Integrate with CI/CD - Test configurations before deployment
3. Build custom modules - For vendor-specific needs

Resources

• Ansible Network Documentation
• Ansible Galaxy - Pre-built roles
• Network to Code - Community resources

Conclusion

Network automation with Ansible is accessible and powerful. Start small, automate one task at a time, and gradually expand your automation footprint.

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