Infrastructure-as-Code: Why It's Essential for Modern DevOps

Written By jameelah mercer

Introduction

Manual infrastructure management doesn’t scale—especially when you're responsible for maintaining the integrity of a national high-performance computing (HPC) data center.

As a DevOps Engineering Intern at the National Energy Research Scientific Computing Center (NERSC), I helped build systems that supported real-time monitoring, environmental sensor accuracy, and intelligent infrastructure alerting. We validated critical hardware through software like OpenDCIM, automated system failure detection, and created tools that visualized resource loads in 3D. But none of it would have been reliable—or sustainable—without a repeatable, version-controlled infrastructure workflow.

That’s where Infrastructure-as-Code (IaC) comes in. By codifying infrastructure in tools like Ansible, teams can move from manual processes to scalable, automated provisioning that’s testable, traceable, and collaborative. At NERSC, workflows powered by automation helped reduce downtime, environmental impact, and time spent debugging hardware drift.

This post explores why IaC—especially with Ansible—is essential to modern DevOps, and how it can help teams build resilient infrastructure from the ground up.

What Is Infrastructure-as-Code?

Infrastructure-as-Code (IaC) is the practice of managing and provisioning infrastructure through code instead of manual processes. Rather than clicking through a dashboard or configuring servers by hand, you define the desired state of your infrastructure in files that can be version-controlled, peer-reviewed, and deployed like any other software artifact.

Ansible approaches IaC with a human-readable, declarative syntax. Using YAML-based playbooks, you can define how systems should be configured, what packages should be installed, and what services should be running—without needing to install agents or run complex pipelines. Ansible connects over SSH, making it especially accessible to teams looking to automate fast without heavy overhead.

Where traditional sysadmin work is prone to drift and human error, Ansible playbooks ensure every environment is configured the same way, every time. From spinning up HPC nodes to automating alerting systems, this kind of automation becomes the backbone of reliable infrastructure.

Why Infrastructure-as-Code Is Essential for Modern DevOps

Modern DevOps is built on the principle of automation, and Infrastructure-as-Code is its foundation. As systems scale and teams grow, it becomes impossible to rely on tribal knowledge, one-off scripts, or undocumented server changes. IaC solves this by giving infrastructure the same rigor and repeatability as application code.

Here’s why it matters:

1. Consistency Across Environments

With Ansible, you can write one playbook and apply it across staging, production, or recovery systems. At NERSC, this meant we could validate that what worked in one rack of servers would behave the same in another—minimizing configuration drift and unexpected behavior.

2. Version Control and Collaboration

Infrastructure changes are tracked in Git. That means every adjustment—whether to a Kubernetes deployment or a data center monitoring script—is reviewed, documented, and revertible. As someone who collaborated across engineers and operations managers, this level of transparency ensured everyone stayed aligned.

3. Faster Recovery and Onboarding

When systems went down or needed to scale quickly, IaC allowed us to bring environments back online with minimal downtime. New engineers could get up to speed faster because infrastructure was readable, centralized, and well-documented.

4. Scalability and Sustainability

IaC isn’t just about speed—it’s also about building sustainable systems. At NERSC, infrastructure automation contributed to a more energy-efficient and financially sustainable data center. We weren’t guessing—we were provisioning based on well-defined code that reflected the real-world state of our systems.

How to Get Started with Infrastructure-as-Code Using Ansible

Adopting Infrastructure-as-Code (IaC) with Ansible begins with more than installing tools—it starts with a mindset shift: treating infrastructure as a collaborative, testable, version-controlled asset. Ansible’s agentless, declarative approach makes it ideal for gradually integrating automation into existing infrastructure while keeping human readability and flexibility intact.

Here’s a detailed roadmap for starting strong with Ansible in production-minded environments:

1. Define a Small, Meaningful Use Case

Begin by selecting a manageable task suitable for automation, such as configuring a development environment or deploying a monitoring agent. Starting with a focused use case allows for incremental learning and minimizes potential disruptions.

2. Install Ansible and Set Up Your Control Node

For Ubuntu:

sudo apt update
sudo apt install ansible -y

For RHEL/CentOS:

sudo yum install epel-release -y
sudo yum install ansible -y

For macOS (with Homebrew):

brew install ansible

Confirm installation:

ansible --version

3. Create Your Inventory File

[web]
web01 ansible_host=192.168.10.10 ansible_user=ubuntu

[monitoring]
prometheus01 ansible_host=192.168.10.20 ansible_user=devops

4. Create Modular, Reusable Playbooks

Organize your playbooks with roles:

ansible-galaxy init roles/prometheus

Within a role:

  • tasks/ – main setup logic
  • handlers/ – services to restart
  • templates/ – dynamic config files
  • defaults/ – default vars

5. Parameterize with Variables and Templates

Use variables to increase flexibility:

global:
  scrape_interval: {{ scrape_interval }}

scrape_configs:
  - job_name: 'node'
    static_configs:
      - targets: {{ prometheus_targets }}

6. Version Control Your Playbooks

git init
git add .
git commit -m "Initial Ansible setup"

7. Test Before Deployment

Use check mode:

ansible-playbook -i inventory playbook.yml --check

Try tools like ansible-lint, molecule, or vagrant to validate roles.

8. Integrate into CI/CD Pipelines

Example GitHub Actions job:

name: Ansible CI

on: [push]

jobs:
  ansible:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v2
      - run: sudo apt update && sudo apt install ansible -y
      - run: ansible-playbook -i inventory playbook.yml --check

9. Document Everything

  • Include a README.md for every role or playbook
  • Comment your YAML clearly
  • Share diagrams or onboarding docs internally

Conclusion

Infrastructure-as-Code isn’t just a tooling trend—it’s a cultural and operational upgrade. With Ansible, teams can automate critical processes, eliminate guesswork, and ensure their infrastructure is as dependable as their codebase.

My experience at NERSC showed how automation and documentation work together to reduce risk and improve collaboration. Whether you're managing a startup’s cloud footprint or maintaining a supercomputing facility, Infrastructure-as-Code enables your infrastructure to scale with confidence—not chaos.

And Ansible is one of the most powerful tools to help you get there.

jameelah mercer
Next

Why Docs-as-Code Matters for Developer Experience