In today's rapidly evolving IT environment, it is crucial to have management and configuration processes for network devices that are as efficient as possible and minimally reliant on manual interventions. Automating these processes brings significant improvements in the efficiency, scalability, and reliability of network infrastructure. One of the tools that has become a standard for automation in recent years is Ansible, an open-source platform for configuration and management of computers. This article focuses on implementing automated provisioning and configuration of network devices using Ansible network automation on the CentOS operating system.

Basic Principles of Ansible

Ansible is an IT process automation tool that enables configuration management, software deployment automation, and development environment orchestration. Its main advantage lies in its simplicity and the ability to use the "Infrastructure as Code" principle. Ansible uses YAML (YAML Ain't Markup Language) for configuration, a readable data format designed for configuration files. For communication with remote devices, it utilizes SSH, eliminating the need for installing a special client on target systems.

Installing Ansible on CentOS

Before commencing automation, it is essential to install Ansible on the CentOS system. The installation process is relatively straightforward, as Ansible is available in the official CentOS repositories. The installation steps are as follows:

1. Open a terminal on your CentOS system.
2. Ensure your system packages are up to date by running sudo yum update.
3. Install Ansible using sudo yum install ansible.
4. Verify the installation with ansible --version, which will display the Ansible version.

Configuring Ansible for Network Device Management

To manage network devices using Ansible, you need to prepare an inventory file containing information about the network devices, and playbooks that define tasks for configuration and management. An inventory file may look like this:

all:
  hosts:
    switch01:
      ansible_host: 192.168.1.1
      ansible_network_os: ios
      ansible_connection: network_cli

In this example, switch01 is the hostname of the network device, ansible_host specifies the IP address of the device, ansible_network_os indicates the device's operating system (Cisco IOS in this case), and ansible_connection sets the type of connection Ansible will use to communicate with the device.

Creating and Running Playbooks

Playbooks are the fundamental building blocks of Ansible for defining and executing tasks on remote devices. Here is a simple playbook example for setting the hostname on a network device:

- name: Configure hostname on network device
  hosts: switch01
  gather_facts: false
  tasks:
    - name: Set hostname
      ios_config:
        lines:
          - hostname switch01-new

This playbook defines a single task, which is setting the new hostname switch01-new on the device specified in the inventory file under the alias switch01. The ios_config module is used for devices running the Cisco IOS.

To run this playbook, use the following command in the terminal:

ansible-playbook -i inventory.yml playbook.yml

Where inventory.yml is your inventory file and playbook.yml is the file containing your playbook.

Security Aspects and Best Practices

When implementing automated provisioning and configuration of network devices, security is paramount. Ensure that:

• Secure protocols like SSH are used for communication between Ansible and managed devices.
• Sensitive data such as passwords and private keys are stored in encrypted files using Ansible Vault.
• Access to inventory files and playbooks is restricted to authorized users only.

Automation as Part of Integration and Delivery

Implementing automated provisioning and configuration of network devices using Ansible is a crucial step towards achieving higher efficiency, scalability, and reliability of network operations. Ansible enables rapid deployment of configurations, reduces the likelihood of human error, and provides the ability for systematic and repeatable deployment of changes.

In the context of advanced CI/CD (Continuous Integration/Continuous Deployment) pipelines, Ansible can be integrated into automated processes for testing and validating network configuration before deployment to production environments. This increases the overall quality and security of the network infrastructure.

In today's world, where rapid response to business demands must be balanced with ensuring high levels of security and reliability of IT services, automation becomes an essential tool for every network administrator. Implementing Ansible on CentOS for automating provisioning and configuration of network devices is an effective step towards achieving these goals.