6.6 - Configuration Management Tools

Greetings, Tech Talkers!

This is Tor, your trusted network engineering uplink! Today, we're exploring the world of Configuration Management Tools, focusing on Ansible and Terraform. These tools are game-changers in network automation, enabling us to manage complex configurations efficiently, consistently, and at scale.

In this article, we'll delve into the capabilities of these tools, how they differ, and how you can leverage them to automate your network infrastructure. By the end, you'll have a solid understanding of how Ansible and Terraform can enhance your network operations.

Let's get started!

What Are Configuration Management Tools?

Configuration Management Tools automate the process of configuring and maintaining systems, ensuring that desired configurations are applied consistently across your infrastructure. They help manage complex deployments, reduce errors, and streamline operations.

Key Benefits:

• Automation: Automate repetitive tasks, saving time and reducing manual errors.

• Consistency: Ensure that configurations are uniform across all devices.

• Scalability: Manage large-scale environments efficiently.

• Version Control: Track changes and maintain historical records of configurations.

Ansible: Agentless Automation

Ansible is an open-source automation tool used for configuration management, application deployment, and task automation. It uses a simple, human-readable language called YAML to define automation jobs in Playbooks.

Key Features:

• Agentless: No software agents are required on target devices; uses SSH or APIs.

• Easy to Learn: Simple syntax and declarative language make it accessible.

• Idempotent: Ensures that applying the same configuration multiple times has the same effect.

• Extensible Modules: Supports a wide range of modules for different platforms and tasks.

How Ansible Works:

• Inventory: Defines the hosts and groups of hosts to manage.

• Playbooks: YAML files that describe the desired state and tasks.

• Modules: Units of work executed on target devices (e.g., network modules).

Example Ansible Playbook:

- name: Configure network devices
  hosts: switches
  gather_facts: no
  connection: network_cli
  tasks:
    - name: Configure interface description
      ios_config:
        lines:
          - description Uplink to Core
        parents: interface GigabitEthernet0/1

Terraform: Infrastructure as Code

Terraform is an open-source tool by HashiCorp that enables you to define and provision infrastructure using a high-level configuration language called HCL (HashiCorp Configuration Language).

Key Features:

• Infrastructure as Code (IaC): Manage infrastructure using code, enabling version control and collaboration.

• Declarative Syntax: Define the desired state, and Terraform handles the provisioning.

• State Management: Keeps track of resource states, enabling incremental changes.

• Provider Plugins: Supports various providers (e.g., AWS, Azure, Cisco) through plugins.

How Terraform Works:

• Configuration Files: Define resources and dependencies in HCL files.

• Providers: Interact with APIs to manage resources.

• State File: Maintains the current state of the infrastructure.

• Execution Plan: Terraform generates a plan showing what actions will be taken.

Example Terraform Configuration:

provider "cisco" {
  address  = "192.168.1.1"
  username = "admin"
  password = "password"
}
resource "cisco_interface" "GigabitEthernet0_1" {
  name        = "GigabitEthernet0/1"
  description = "Uplink to Core"
  enabled     = true
}

Comparing Ansible and Terraform

Capabilities of Ansible and Terraform

Ansible Capabilities:

• Network Automation:

  • Supports multiple network vendors (Cisco, Juniper, Arista).

  • Manages device configurations, OS upgrades, and backups.

• Playbooks and Roles:

  • Reusable code blocks for common tasks.

• Dynamic Inventories:

  • Integrate with cloud providers to manage dynamic hosts.

Terraform Capabilities:

• Infrastructure Provisioning:

  • Creates and manages resources across multiple providers.

• Dependency Management:

  • Understands resource relationships and orchestrates accordingly.

• Plan and Apply Workflow:

  • Generates execution plans for review before applying changes.

Using Ansible for Network Configuration

Step-by-Step Example:

1. Install Ansible:

   $ sudo apt-get install ansible

2. Define Inventory File (`hosts`):

   [switches]
   switch1 ansible_host=192.168.1.10 ansible_network_os=ios

3. Create Playbook (`configure_interfaces.yml`):

   ---
   - name: Configure interfaces on switches
     hosts: switches
     gather_facts: no
     connection: network_cli
     tasks:
       - name: Configure interface description
         ios_config:
           lines:
             - description Uplink to Core
           parents: interface GigabitEthernet0/1

4. Run Playbook:

   $ ansible-playbook -i hosts configure_interfaces.yml

Benefits:

• Automate configuration across multiple devices.

• Ensure consistency and compliance.

• Reduce manual effort and errors.

Using Terraform for Network Provisioning

Step-by-Step Example:

1. Install Terraform:

Download from the [HashiCorp website](https://www.terraform.io/downloads.html) and add it to your PATH.

2. Define Provider Configuration (`provider.tf`):

   provider "cisco" {
     address  = "192.168.1.1"
     username = "admin"
     password = "password"
   }

3. Create Resource Definitions (`main.tf`):

   resource "cisco_interface" "GigabitEthernet0_1" {
     name        = "GigabitEthernet0/1"
     description = "Uplink to Core"
     enabled     = true
   }

4. Initialize Terraform:

   $ terraform init

5. Plan Changes:

   $ terraform plan

6. Apply Changes:

   $ terraform apply

Benefits:

- Define infrastructure as code.

- Maintain a clear view of changes with execution plans.

- Reproduce environments consistently.

Best Practices

For Ansible:

• Use Roles: Organize playbooks into roles for reusability.

• Variables and Templates: Use variables and Jinja2 templates for dynamic configurations.

• Idempotency: Ensure playbooks can run multiple times without unintended effects.

• Version Control: Keep playbooks in a version control system like Git.

For Terraform:

• State Management: Secure state files, especially when containing sensitive information.

• Modules: Use modules to encapsulate and reuse configurations.

• Environment Separation: Use workspaces or separate state files for different environments (dev, prod).

• Review Plans: Always review `terraform plan` output before applying changes.

When to Use Ansible vs. Terraform

Ansible is Ideal For:

• Ongoing configuration management.

• Patching and updates.

• Orchestrating ad-hoc tasks.

Terraform is Ideal For:

• Provisioning new infrastructure.

• Managing cloud resources.

• Infrastructure lifecycle management.

Combined Use:

• Use Terraform to provision infrastructure and Ansible to configure it post-deployment.

Wrapping It Up

Ansible and Terraform are powerful tools that can significantly enhance your network automation capabilities. By understanding their strengths and how to use them effectively, you can automate complex tasks, reduce errors, and improve the scalability of your network operations.

Until next time, Tech Talkers, keep automating and optimizing your network configurations!

Thanks,

Tor – Your trusted network engineering uplink