Infrastructure as Code: Terraform, Pulumi, and Ansible Advanced Use Cases

Infrastructure as Code (IaC) revolutionizes how we manage infrastructure—allowing you to define, provision, and update infrastructure using code. Tools like Terraform, Pulumi, and Ansible have become core parts of modern DevOps pipelines.

In this article, we'll go beyond the basics and explore advanced use cases for these tools, comparing how they solve real-world infrastructure challenges.

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🧠 What Is Infrastructure as Code?

Infrastructure as Code means managing and provisioning infrastructure (networks, VMs, databases, etc.) using declarative or imperative code.

Benefits:

• Repeatability and consistency

• Version control for infrastructure

• Reduced human error

• Faster provisioning and automation

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🛠️ Tools We’ll Explore

Tool	Language	Paradigm	Best For
Terraform	HCL (HashiCorp)	Declarative	Cloud provisioning (multi-cloud)
Pulumi	Python, TypeScript, Go, etc.	Imperative	Complex logic, cloud-native teams
Ansible	YAML + Jinja2	Declarative	Configuration management, provisioning

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🧰 Terraform: Advanced Use Cases

1. Modular Infrastructure

Terraform lets you break infrastructure into reusable modules.

h
module "vpc" {
  source = "./modules/vpc"
  cidr_block = "10.0.0.0/16"
}

📌 Why use it? Makes infra DRY, scalable, and easier to test.

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2. Workspaces for Multi-Environment Deployments

Workspaces isolate state for environments like dev/staging/prod.

bash
terraform workspace new dev
terraform apply

📌 Great for managing parallel environments without duplicating code.

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3. Dynamic Blocks and Expressions

Terraform supports logic inside resources:

h
resource "aws_security_group_rule" "example" {
  count = length(var.ports)
  from_port = var.ports[count.index]
  ...
}

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4. Remote State & State Locking

Use remote backends (e.g., S3 with DynamoDB) for team collaboration and to prevent state corruption.

hcl
backend "s3" {
  bucket = "my-terraform-state"
  key    = "network/terraform.tfstate"
  region = "us-west-1"
}

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💻 Pulumi: Advanced Use Cases

1. Full Infrastructure in Real Programming Languages

You can use TypeScript, Python, Go, or C# to define infrastructure, which enables:

• Reusable logic

• Loops and conditionals

• Native language tooling

ts
for (let i = 0; i < 3; i++) {
  new aws.ec2.Instance(`web-${i}`, {
    ami: "ami-xyz",
    instanceType: "t2.micro",
  });
}

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2. Combining Infrastructure with Application Logic

Pulumi lets you provision infrastructure and deploy apps in the same language/project.

ts
const bucket = new aws.s3.Bucket("appBucket");
const upload = new aws.s3.BucketObject("index", {
  bucket: bucket,
  content: "Hello, world!",
});

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3. Advanced Secrets Handling

Pulumi supports encrypted secrets natively, no external tooling required:

ts
const dbPassword = new pulumi.Config().requireSecret("dbPassword");

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4. Multi-Cloud Abstraction

You can define cloud-agnostic abstractions or write wrappers to deploy similar infra to different clouds programmatically.

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🧪 Ansible: Advanced Use Cases

1. Agentless Server Provisioning at Scale

Use dynamic inventories (like AWS EC2, Azure, GCP) to manage thousands of servers:

bash
ansible-inventory -i aws_ec2.yaml --graph

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2. Immutable Infrastructure with Ansible + Packer

Use Ansible as a provisioner in a Packer template to build golden images:

json
"provisioners": [{
  "type": "ansible",
  "playbook_file": "playbook.yml"
}]

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3. Automating Application Rollbacks

Write idempotent playbooks that deploy app versions using variables or Ansible Tower:

yaml
- name: Deploy app
  vars:
    app_version: "2.3.1"
  ...

Set app_version dynamically based on build pipelines or rollback trigger.

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4. Ansible Vault for Secrets

Encrypt variables or files:

bash
ansible-vault encrypt secrets.yml
ansible-playbook site.yml --ask-vault-pass

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🧬 Combining the Tools

Use Case	Recommended Tool
Provisioning Cloud Infrastructure	Terraform / Pulumi
Configuring OS and Apps	Ansible
Application + Infra in one codebase	Pulumi
Immutable Image Building	Packer + Ansible
Multi-environment deployments	Terraform Workspaces

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✅ Final Thoughts

Each tool in the IaC toolbox has its own strengths:

• Terraform is ideal for large-scale, declarative infrastructure.

• Pulumi is excellent for developers wanting to use real languages and combine app + infra.

• Ansible is best for configuration management and server-level automation.

The real power comes from combining them wisely based on your team’s needs and infrastructure complexity.