Terraform and Ansible

Terraform and Ansible are popular tools in the DevOps community, used for infrastructure as code (IaC) and automation tasks.

They serve different, yet complementary purposes.

Table of Contents

• Terraform and Ansible
• Terraform
  • Terraform Examples
• Ansible
  • Ansible Examples
• Relationship between Terraform and Ansible
  • Example Workflow
  • Integration Use Case
• tl;dr

Terraform

Terraform, developed by HashiCorp, is used for building, changing, and versioning infrastructure safely and efficiently.

It supports a wide range of cloud providers (like AWS, Google Cloud, Azure) as well as on-prem resources.

Terraform uses declarative configuration files to manage and provision the infrastructure.

Terraform Examples

1. Provisioning a Virtual Machine on AWS:

   resource "aws_instance" "example" {
     ami           = "ami-0c55b159cbfafe1f0"
     instance_type = "t2.micro"
   }
   

   This Terraform script creates a new EC2 instance of type t2.micro on AWS.

2. Creating a Network on Google Cloud:

   resource "google_compute_network" "vpc_network" {
     name                    = "terraform-network"
     auto_create_subnetworks = "true"
   }
   

   This script provisions a new VPC network in Google Cloud with auto-created subnetworks.

Ansible

Ansible, developed by Red Hat, is an open-source software provisioning, configuration management, and application-deployment tool.

What it does: * Uses a procedural style for automation.
* Deploys apps. * Manages systems and devices.

Unlike Terraform, Ansible uses an agentless architecture. Ansible relies on SSH for communication to managed nodes.

Ansible Examples:

1. Configuring a Web Server:

   - name: Ensure Apache is at the latest version
     yum:
       name: httpd
       state: latest
   - name: Write the Apache config file
     template:
       src: /srv/httpd.j2
       dest: /etc/httpd.conf
   

   This Ansible playbook ensures that Apache (httpd) is installed at its latest version and configures it using a template.

2. Adding a User to Multiple Servers:

   - name: Add a new user
     user:
       name: username
       state: present
       groups: "wheel"
       append: yes
   

   This playbook adds a new user to the wheel group across all managed servers.

Relationship between Terraform and Ansible

• Terraform is for setting up and tearing down entire infrastructures.
• Ansible is for the setting up the detailed configuration of the software on those infrastructures.

They can be used together in a workflow where Terraform provisions the hardware, and Ansible then configures the software.

Example Workflow

1. Terraform is used to provision a set of VMs and a load balancer in AWS.
2. Ansible takes over to install a web server on the VMs, deploy the application, and ensure all configurations are correct.

Integration Use Case

• After Terraform provisions new AWS EC2 instances, it outputs the IP addresses of the new instances.
• Ansible uses those IP addresses (perhaps dynamically generated inventory) to configure software, deploy applications, and ensure the servers are ready for traffic.

This approach leverages the strengths of both tools: Terraform's ability to manage infrastructure and Ansible's capability to configure and deploy applications onto that infrastructure.

tl;dr:

• Terraform is for setting up and tearing down entire infrastructures.
• Ansible is for the setting up the detailed configuration of the software on those infrastructures.