Efficiency and resilience: how IaC revolutionizes infrastructure deployment

Five years ago, deploying cloud infrastructure took weeks of manual work: configuring servers one by one, creating networks, defining permissions, installing dependencies. Today, with Infrastructure as Code (IaC), that same process shrinks to minutes—with greater reliability and zero human error.

The question is no longer whether to adopt IaC, but how much money and time you're losing by not doing so. In this article, we explore how IaC has become standard practice for teams that need to scale without sacrificing stability.

What is Infrastructure as Code?

IaC is the practice of defining your entire infrastructure—servers, networks, databases, permissions, services—in versionable text files (YAML, JSON, HCL). Instead of configuring manually from web consoles or SSH, you describe what you need in code, and tools like Terraform, AWS CloudFormation or Ansible deploy it automatically.

It's the difference between building a house by laying each brick by hand versus printing the entire house from a precise digital blueprint.

The benefits that transform operations

1. Speed: from days to minutes

Manually setting up a production environment on AWS (VPC, subnets, load balancers, auto-scaling groups, RDS, IAM permissions) can take 3-5 days if you're experienced. With IaC, you run one command and in 20 minutes you have everything running.

Real case: A team of 12 developers in Madrid needed to replicate their staging environment for testing. Manually: 2 days. With Terraform already configured: 18 minutes.

2. Versioning and auditability: Git for infrastructure

If your infrastructure lives in Git files, you can:

• See who changed what, when and why (commits with messages)
• Roll back if something fails (instant rollback)
• Review changes before applying them (pull requests)
• Pass security audits without manual documentation

This is especially critical in regulated sectors (fintech, healthtech) where every change must be traceable.

3. Elimination of human error

Manual configuration is error-prone: forgetting to open a port, getting permissions wrong, using inconsistent configurations across environments. With IaC, you define once and replicate infinitely with no deviations.

"We used to lose half a day debugging subtle differences between staging and production. Now staging IS production, just with fewer resources. The code is identical."

4. Scalability without friction

Need to create 5 identical environments for different clients? Want to test an alternative architecture without risking production? With IaC, you clone, tweak parameters and deploy. No touching web consoles. No support tickets.

5. Accelerated disaster recovery

If your AWS region fails or you need to migrate to another cloud (multi-cloud), with IaC you rebuild your entire infrastructure in another region/provider by running the same code. The RTO (Recovery Time Objective) drops from days to hours.

Practical case: deploying a backend on AWS with IaC

Let's look at a real example we've implemented dozens of times:

Requirement: Deploy a NestJS backend on AWS with:

• CPU-based auto-scaling
• Managed PostgreSQL database (RDS)
• Load balancer with SSL certificate
• Authentication with Cognito
• Centralized logs in CloudWatch
• Automated backups

Manual approach (old)

1. Day 1: Create VPC, public/private subnets, internet gateway, route tables
2. Day 2: Configure security groups, EC2 instances, install dependencies
3. Day 3: Set up RDS, configure backups, connect to backend
4. Day 4: Configure ALB, SSL certificate, health checks
5. Day 5: Configure auto-scaling, Cognito, testing

Total: 5 days + risk of inconsistent configuration

IaC approach with Terraform (modern)

terraform init
terraform plan    # Review changes
terraform apply   # Deploy everything

Total: 20 minutes + identical infrastructure every time

Best practices for implementing IaC

From our 12 DevSecOps transformations, these are the key lessons:

1. Start modular from day one

Don't write a 2,000-line file. Create reusable modules (networking, compute, databases). It enables flexible composition and independent testing.

2. State management is critical

If you use Terraform, the state file (.tfstate) is your source of truth. Store it in a remote backend (S3 + DynamoDB lock) for teamwork. Losing the state = disaster.

3. Integrate with CI/CD from day 1

Your pipeline should:

• Run terraform plan on every pull request
• Require manual approval before apply
• Validate security policies (Checkov, tfsec)
• Notify changes in Slack/Teams

4. Keep variables and secrets separate

Never hardcode credentials in code. Use AWS Secrets Manager, HashiCorp Vault, or environment variables injected from CI/CD. Everything in Git must be public-safe.

5. Document the "why", not the "what"

The code already shows what you're deploying. Comments should explain why you made architectural decisions (e.g. "public subnet because the ALB needs public IPs").

Tools: Terraform, CloudFormation or Ansible?

There's no single answer, but these are our recommendations depending on context:

• Terraform: Multi-cloud, huge community, HCL more readable than JSON. Default for most cases.
• AWS CloudFormation: If you're 100% on AWS and value native integration (StackSets, drift detection).
• Pulumi: If your team prefers TypeScript/Python over DSLs. More flexible but less mature.
• Ansible: Better for post-deployment software configuration, not so much for provisioning cloud infrastructure.

The real cost of not adopting IaC

Beyond speed, the cost of not having IaC is brutal:

• Bus factor = 1: Only one person knows how the infra works. If they leave, you're blocked.
• Uncontrollable drift: Production diverges from staging without anyone knowing when or why.
• Disasters with no recovery plan: You can't rebuild your infra quickly because it isn't codified.
• Slow onboarding: New devs take weeks to understand the architecture because there's no living documentation (the code is).
• Impossible compliance: Security audits require screenshots and outdated manual documentation.

Next steps: from manual to automated

If you still manage infrastructure manually, the path toward IaC doesn't have to be disruptive:

1. Audit of the current state (1-2 weeks): Document your existing infrastructure
2. Codify non-prod environments first (2-3 weeks): Start with dev/staging, not production
3. Implement CI/CD for infra (1 week): A pipeline that validates and deploys changes
4. Progressive migration of prod (2-4 weeks): Import existing resources into IaC with no downtime
5. Continuous optimization (ongoing): Refactor modules, improve policies

Total: 6-10 weeks of transformation for a technical debt that was costing you months of manual work per year.

Is your team ready for IaC?

If you're in any of these situations, IaC should be a priority now:

• Creating new environments takes you more than 1 day
• You've had incidents caused by incorrect manual configuration
• You can't explain exactly how your production infra is configured
• Onboarding new devs/devops takes >2 weeks just to understand the architecture
• You need to comply with SOC2, ISO27001 or similar

At onext, we've implemented complete DevSecOps transformations—including IaC, CI/CD, observability and security—in 6-10 weeks. Without stopping your current deliveries.