Include Terraform dependency lock file

Why? Because in the beginning of an initialization it save modules and providers checksums. Thanks to this you can track if anything changed in the version you used.

Source: https://www.hashicorp.com/en/blog/terraform-security-5-foundational-practices

A cost optimized AWS environment

Costs saving:

• Saving Plans,
• Reserved Instances,
• change your default payment method to avoid currency conversion,
• Spot Instances (a development environment),
• Data Lifecycle Management for EBSes (remove unneeded EBSes),
• S3:
• a lifecycle policy for a bucket (move your data into a cheaper storage class),
• use VPC endpoints (AWS charges for outbound data transfer),
• use Graviton instance type,
• use Lambda to switch off your instances (for example EC2, RDS) out of working hours on your development environments.
• choose a right region because a resource can be cheaper in a different region,
• Parameter Store instead of Secrets Manager if you don't need a versioning or rotation,
• ElastiCache for Redis:
• consider using ElastiCache for Valkey,
• CloudWatch:
• logs retention,
• NAT Gateway:
• consider using fck-nat,
• Route 53:
• check your records TTLs - the lower TTL the less you pay.
  

Monitoring:

• Cost Explorer,
• Cost and Usage Reports,
• Cost Anomaly Detection,
• Budgets,
• Trusted Advisor,
• cost allocation tags,
• AWS Compute Optimizer,
• S3 Storage Lens.