Automated EC2 & RDS Rightsizing

Automate Amazon EC2 and Amazon RDS rightsizing using EventBridge Scheduler, AWS Lambda and Terraform.

Not every workload requires the same capacity 24/7. This solution automatically upgrades or downgrades EC2 instances and RDS databases based on scheduled dates and times, helping reduce AWS costs while ensuring sufficient capacity when needed.

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Architecture

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Features

EC2 Rightsizing

• Scheduled EC2 instance upgrades
• Scheduled EC2 instance downgrades
• Multiple EC2 instance support
• Recurring schedules
• One-time event schedules
• Date-range schedules
• Automated stop, resize and start workflow

RDS Rightsizing

• Scheduled RDS database upgrades
• Scheduled RDS database downgrades
• Multiple database support
• Recurring schedules
• One-time event schedules
• Date-range schedules
• Automated database class modification

Operational Features

• Event-driven architecture
• Serverless automation
• Terraform Infrastructure as Code
• CloudWatch logging
• SNS notifications
• Configuration-driven deployment

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Scheduling Use Cases

The following examples use the configured schedule_timezone.

Daily Business Hours

Time	Action
08:00 AM	Upgrade
07:00 PM	Downgrade

Weekly Schedule

Schedule	Action
Every Wednesday 08:00 AM	Upgrade
Every Wednesday 06:00 PM	Downgrade

One-Time Event

Date	Action
2026-11-25	Upgrade
2026-12-01	Downgrade

Date-Range Schedule

Configuration	Value
Start Date	2026-06-01
End Date	2026-11-30
Upgrade	Every Wednesday 08:00 AM
Downgrade	Every Wednesday 06:00 PM

Scheduled Capacity Expansion

Date	Action
November 1	Increase Capacity
January 5	Restore Normal Capacity

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Prerequisites

• AWS Account
• Terraform >= 1.10, < 2.0
• AWS CLI configured

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Repository Structure

automated-ec2-rds-rightsizing/
├── terraform/
│
│   ├── modules/
│   │   ├── naming/
│   │   ├── iam/
│   │   ├── sns/
│   │   ├── lambda/
│   │   └── eventbridge/
│   │
│   ├── main.tf
│   ├── variables.tf
│   ├── outputs.tf
│   ├── providers.tf
│   ├── versions.tf
│   └── terraform.tfvars.example
│
├── lambda/
│   ├── ec2_resizer.py
│   └── rds_resizer.py
│
├── diagrams/
│   └── architecture.png
│
└── README.md

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Example Configuration

Recurring Weekly Schedule

mobile_app_server = {

  instance_id = "i-0123456789abcdef0"

  upgrade_type   = "t3.large"
  downgrade_type = "t3.small"

  upgrade_schedule = {
    expression = "cron(0 8 ? * WED *)"
    start_date = "2026-06-01T00:00:00Z"
    end_date   = "2026-11-30T23:59:59Z"
  }

  downgrade_schedule = {
    expression = "cron(0 18 ? * WED *)"
    start_date = "2026-06-01T00:00:00Z"
    end_date   = "2026-11-30T23:59:59Z"
  }
}

One-Time Special Event (EC2)

mobile_app_server = {

  instance_id = "i-0abcdef1234567890"

  upgrade_type   = "c6i.2xlarge"
  downgrade_type = "t3.medium"

  upgrade_schedule = {
    expression = "at(2026-11-25T06:00:00)"
  }

  downgrade_schedule = {
    expression = "at(2026-12-01T00:00:00)"
  }
}

One-Time Special Event (RDS)

mobile_app_database = {

  db_identifier = "mobile-app-mysql"

  upgrade_class   = "db.r6g.xlarge"
  downgrade_class = "db.t3.medium"

  upgrade_schedule = {
    expression = "at(2026-07-15T00:00:00)"
  }

  downgrade_schedule = {
    expression = "at(2026-07-16T00:00:00)"
  }
}

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Timezone

The solution supports configurable EventBridge Scheduler timezones.

Example:

schedule_timezone = "Asia/Singapore"

Schedules run according to the configured timezone allowing automation to align with local business hours.

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Deployment

Initialize Terraform:

terraform init

Validate configuration:

terraform validate

Review planned changes:

terraform plan

Deploy infrastructure:

terraform apply

Remove infrastructure:

terraform destroy

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License

MIT License