Infrastructure as Code: Why It Matters for Your Business

Manual infrastructure doesn’t scale. Infrastructure as Code does.

The Problem with Manual Infrastructure

When infrastructure is created by clicking through consoles:

• No history: Who changed what, when, and why?
• No reproducibility: Can you rebuild this environment from scratch?
• No review process: Changes go live without oversight
• Configuration drift: Production slowly diverges from staging
• Single points of failure: Only one person knows how it’s set up

This works for a weekend project. It doesn’t work for a business.

What Infrastructure as Code Actually Means

Infrastructure as Code (IaC) means defining your infrastructure in version-controlled files:

// This is infrastructure
const database = new rds.DatabaseInstance(this, "Database", {
  engine: rds.DatabaseInstanceEngine.postgres({ version: rds.PostgresEngineVersion.VER_15 }),
  instanceType: ec2.InstanceType.of(ec2.InstanceClass.T4G, ec2.InstanceSize.SMALL),
  vpc,
  allocatedStorage: 20,
  backupRetention: Duration.days(7),
});

This code:

• Lives in Git with full history
• Gets reviewed before merging
• Deploys consistently every time
• Can recreate the entire environment

The Business Case

1. Faster deployments

Approach	Time to Deploy New Environment
Manual	4-8 hours (if documented)
IaC	15-30 minutes

When a new client needs an isolated environment, or you need to spin up a demo, IaC makes it trivial.

2. Fewer errors

Manual deployments have a ~5-10% error rate on complex changes. IaC reduces this to near zero because:

• Changes are tested in staging first
• Code review catches mistakes
• The same code runs every time

3. Disaster recovery

If your AWS account got compromised tomorrow, could you rebuild?

With IaC: Run cdk deploy and you’re back online.

Without IaC: Days of manual reconstruction, assuming someone remembers how it was configured.

4. Knowledge transfer

When someone leaves the team, their infrastructure knowledge shouldn’t leave with them. With IaC, everything is documented in code.

Choosing a Tool

Three main options for AWS:

AWS CDK (Cloud Development Kit)

const bucket = new s3.Bucket(this, "DataBucket", {
  encryption: s3.BucketEncryption.S3_MANAGED,
  versioned: true,
  lifecycleRules: [{
    expiration: Duration.days(90),
    transitions: [{
      storageClass: s3.StorageClass.GLACIER,
      transitionAfter: Duration.days(30),
    }],
  }],
});

Best for: Teams comfortable with TypeScript/Python, complex infrastructure, AWS-only environments.

Strengths:

• Full programming language (loops, conditions, abstractions)
• Strong typing catches errors early
• High-level constructs reduce boilerplate

Terraform

resource "aws_s3_bucket" "data" {
  bucket = "my-data-bucket"
}

resource "aws_s3_bucket_lifecycle_configuration" "data" {
  bucket = aws_s3_bucket.data.id

  rule {
    id     = "archive"
    status = "Enabled"

    transition {
      days          = 30
      storage_class = "GLACIER"
    }

    expiration {
      days = 90
    }
  }
}

Best for: Multi-cloud environments, teams with existing Terraform experience.

Strengths:

• Cloud-agnostic
• Mature ecosystem
• Large community

CloudFormation

Resources:
  DataBucket:
    Type: AWS::S3::Bucket
    Properties:
      BucketEncryption:
        ServerSideEncryptionConfiguration:
          - ServerSideEncryptionByDefault:
              SSEAlgorithm: AES256
      LifecycleConfiguration:
        Rules:
          - Status: Enabled
            Transitions:
              - StorageClass: GLACIER
                TransitionInDays: 30
            ExpirationInDays: 90

Best for: Simple setups, teams already invested in CloudFormation.

Strengths:

• Native AWS support
• No additional tooling required
• Direct AWS integration

Our recommendation

CDK for most projects. The productivity gains from using a real programming language outweigh the learning curve.

Getting Started

Project structure

infrastructure/
├── bin/
│   └── app.ts           # Entry point
├── lib/
│   ├── stacks/
│   │   ├── network.ts   # VPC, subnets, security groups
│   │   ├── database.ts  # RDS, ElastiCache
│   │   ├── compute.ts   # Fargate, Lambda
│   │   └── cdn.ts       # CloudFront, S3
│   └── constructs/
│       ├── static-site.ts
│       └── fargate-api.ts
├── cdk.json
├── package.json
└── tsconfig.json

Start simple

Don’t try to codify everything at once. Start with:

1. One environment (production or staging)
2. Core infrastructure (database, compute, networking)
3. New resources only (don’t migrate existing manual resources immediately)

Example: Basic web app infrastructure

// lib/stacks/app-stack.ts
export class AppStack extends Stack {
  constructor(scope: Construct, id: string, props: AppStackProps) {
    super(scope, id, props);

    // Networking
    const vpc = new ec2.Vpc(this, "Vpc", {
      maxAzs: 2,
      natGateways: 1,
    });

    // Database
    const database = new rds.DatabaseInstance(this, "Database", {
      engine: rds.DatabaseInstanceEngine.postgres({
        version: rds.PostgresEngineVersion.VER_15,
      }),
      instanceType: ec2.InstanceType.of(ec2.InstanceClass.T4G, ec2.InstanceSize.MICRO),
      vpc,
      vpcSubnets: { subnetType: ec2.SubnetType.PRIVATE_ISOLATED },
      credentials: rds.Credentials.fromGeneratedSecret("postgres"),
    });

    // Application
    const cluster = new ecs.Cluster(this, "Cluster", { vpc });

    new ecs_patterns.ApplicationLoadBalancedFargateService(this, "Service", {
      cluster,
      memoryLimitMiB: 512,
      cpu: 256,
      taskImageOptions: {
        image: ecs.ContainerImage.fromEcrRepository(props.repository),
        secrets: {
          DATABASE_URL: ecs.Secret.fromSecretsManager(database.secret!),
        },
      },
    });
  }
}

Common Patterns

Environment separation

// bin/app.ts
const app = new cdk.App();

new AppStack(app, "AppStaging", {
  env: { account: "123456789", region: "us-east-1" },
  environment: "staging",
  instanceSize: "micro",
});

new AppStack(app, "AppProduction", {
  env: { account: "987654321", region: "us-east-1" },
  environment: "production",
  instanceSize: "small",
});

Same code, different configurations. Staging and production stay in sync.

Secrets management

Never hardcode secrets:

// Bad
const apiKey = "sk-1234567890";

// Good
const apiKey = secretsmanager.Secret.fromSecretNameV2(
  this, "ApiKey", "/myapp/api-key"
);

Cross-stack references

// Network stack exports VPC
export class NetworkStack extends Stack {
  public readonly vpc: ec2.Vpc;

  constructor(scope: Construct, id: string, props?: StackProps) {
    super(scope, id, props);
    this.vpc = new ec2.Vpc(this, "Vpc", { maxAzs: 2 });
  }
}

// App stack imports VPC
const networkStack = new NetworkStack(app, "Network");
new AppStack(app, "App", { vpc: networkStack.vpc });

Deployment Workflow

Local development

# See what will change
cdk diff

# Deploy to your account
cdk deploy

CI/CD integration

# .github/workflows/infrastructure.yml
name: Infrastructure

on:
  push:
    branches: [main]
    paths: ['infrastructure/**']

jobs:
  deploy:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4

      - name: Configure AWS credentials
        uses: aws-actions/configure-aws-credentials@v4
        with:
          role-to-assume: ${{ secrets.AWS_ROLE_ARN }}
          aws-region: us-east-1

      - name: Install dependencies
        run: cd infrastructure && npm ci

      - name: CDK diff
        run: cd infrastructure && npx cdk diff

      - name: CDK deploy
        run: cd infrastructure && npx cdk deploy --require-approval never

Migration Strategy

For existing manual infrastructure:

Phase 1: Import

Use cdk import to bring existing resources under IaC management:

cdk import AppStack
# Follow prompts to import existing resources

Phase 2: Parity

Ensure the IaC definition matches reality:

cdk diff
# Should show no changes if import was successful

Phase 3: Iteration

Now all changes go through code:

# Make change in code
git commit -m "Increase database instance size"
git push

# CI/CD deploys the change

Mistakes to Avoid

1. Giant monolithic stacks

// Bad: Everything in one stack
class EverythingStack extends Stack {
  // 2000 lines of resources
}

// Good: Logical separation
class NetworkStack extends Stack { }
class DatabaseStack extends Stack { }
class ComputeStack extends Stack { }

2. Ignoring state management

Both Terraform and CDK track state. Understand where state lives and how to handle state conflicts.

3. No environment separation

// Bad: Hardcoded values
const instanceType = "t4g.large";

// Good: Environment-specific configuration
const instanceType = props.environment === "production"
  ? "t4g.large"
  : "t4g.micro";

4. Skipping code review

Infrastructure changes should get the same review rigor as application code. A bad infrastructure change can take down production.

Measuring Success

After implementing IaC, track:

Metric	Before IaC	After IaC
Deployment time	Hours	Minutes
Failed deployments	5-10%	<1%
Time to spin up new env	Days	Hours
Configuration drift incidents	Monthly	Never
Bus factor	1-2 people	Team-wide

Lessons Learned

1. Start with new projects. Migrating existing infrastructure is harder than starting fresh.

2. Invest in learning. IaC has a learning curve, but it pays off quickly.

3. Don’t over-engineer. Start simple, add complexity as needed.

4. Test in staging. Never deploy infrastructure changes directly to production.

5. Document decisions. Code shows what, comments explain why.

---

Manual infrastructure is technical debt that compounds over time. Infrastructure as Code is an investment that pays dividends with every deployment.