Infrastructure as Code
Terraform on AWS
Deploy AWS infrastructure reliably with Terraform — version control, testing, and multi-environment management.
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Summary
Infrastructure as Code with Terraform: state management, best practices, and multi-environment AWS deployments.
Key Facts
- • Deploy AWS infrastructure reliably with Terraform — version control, testing, and multi-environment management
- • How do I manage Terraform state in AWS
- • Use S3 for remote state with DynamoDB for state locking
- • Enable versioning and encryption on the S3 bucket
- • Use AWS Secrets Manager or Parameter Store to store secrets
Entity Definitions
- EC2
- EC2 is relevant to terraform on aws.
- S3
- S3 is relevant to terraform on aws.
- RDS
- RDS is relevant to terraform on aws.
- DynamoDB
- DynamoDB is relevant to terraform on aws.
- VPC
- VPC is relevant to terraform on aws.
- Secrets Manager
- Secrets Manager is relevant to terraform on aws.
- AWS Secrets Manager
- AWS Secrets Manager is relevant to terraform on aws.
- Parameter Store
- Parameter Store is relevant to terraform on aws.
- Infrastructure as Code
- Infrastructure as Code is relevant to terraform on aws.
- Terraform
- Terraform is relevant to terraform on aws.
What is Terraform?
Terraform is an open-source Infrastructure as Code tool that lets you define AWS infrastructure in HCL (HashiCorp Configuration Language). Instead of clicking through the AWS Console, you write code that describes your desired infrastructure state, then Terraform creates/updates resources to match.
Why Terraform for AWS?
Reproducibility
- Same infrastructure code creates identical resources
- Environments stay consistent (dev/staging/prod match exactly)
Version Control
- Infrastructure changes tracked in Git
- Review and approval process for infrastructure changes
- Rollback capability if changes break something
Cost Visibility
- Before applying changes, see what will be created (cost estimation)
- Catch expensive mistakes in
terraform plan
Scalability
- Modules enable code reuse across projects
- State management scales to hundreds of resources
Core Terraform Concepts for AWS
Providers: AWS provider tells Terraform how to interact with AWS API
Resources: aws_instance, aws_s3_bucket, aws_rds_cluster — what you’re creating
Data Sources: Reference existing AWS resources without managing them
State File: Terraform’s database of current infrastructure (never commit to Git)
Modules: Reusable Terraform code (like functions in programming)
State Management Best Practices
Remote State (required for teams)
- Store state in S3 with versioning enabled
- Enable DynamoDB for state locking (prevents concurrent writes)
- Encrypt state file (sensitive data like passwords)
State Isolation
- One state file per environment (dev.tfstate, prod.tfstate)
- Use workspaces or separate directories
- Prevents accidental production changes
Common AWS + Terraform Patterns
Multi-Environment (dev/staging/prod)
- Same Terraform code, different variables per environment
terraform workspacesor separate directories
Multi-Region
- AWS provider aliases for different regions
- Replicate infrastructure across regions with minimal code duplication
Modules for Reusability
- VPC module: networking for any project
- RDS module: databases with standard configuration
- Share modules across teams via private module registry
Common Pitfalls
Mistake 1: Mixing manual AWS Console changes with Terraform. Terraform doesn’t know about manual changes; they cause drift.
Mistake 2: Committing state files or secrets to Git. Use .gitignore and .tfignore. Store secrets in AWS Secrets Manager.
Mistake 3: Large monolithic Terraform configs. Break into modules. Smaller configs are easier to review and test.
Mistake 4: Not using terraform plan before applying. Always review the plan; catches mistakes before they become expensive.
Getting Started with Terraform on AWS
- Install Terraform
- Configure AWS credentials (AWS CLI profile or environment variables)
- Create
main.tfwith AWS provider - Define resources: VPC, subnets, EC2 instances, databases
- Run
terraform planto preview changes - Run
terraform applyto create resources - Store state remotely (S3 + DynamoDB)
- Track code changes in Git
Related Services
Frequently Asked Questions
How do I manage Terraform state in AWS?
Use S3 for remote state with DynamoDB for state locking. Enable versioning and encryption on the S3 bucket. Never store state locally in production. Use `terraform_remote_state` to reference state from other configurations.
What is the best Terraform module structure for AWS?
Organize modules by resource type (compute, database, networking). Each module should have clear inputs, outputs, and documentation. Create a module registry in your organization for shared modules. Use semantic versioning for module releases.
How do I handle secrets in Terraform?
Never commit secrets to version control. Use AWS Secrets Manager or Parameter Store to store secrets. Reference them in Terraform via `aws_secretsmanager_secret_version` or `aws_ssm_parameter`. Alternatively, use Terraform Cloud/Enterprise with encrypted variables.
What are Terraform best practices for AWS?
Use workspaces or separate state files for different environments. Implement state locking to prevent concurrent modifications. Use data sources for existing resources. Keep modules small and focused. Test infrastructure changes with `terraform plan` before applying.
How do I migrate existing AWS infrastructure to Terraform?
Use `terraform import` to import existing resources. Write Terraform code to match the imported resources. Test with `terraform plan` to verify no changes. For large migrations, use tools like Terraformer to auto-generate code from AWS resources.
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