EC2 Zombie Killer

This repository packages a scheduled AWS Lambda job built with lambdacron. The job scans EC2 instances for a configurable tag key whose value is the maximum allowed uptime in hours, then either notifies, stops, or terminates instances that have exceeded that limit.

The scheduled Lambda lives in lambda/docker/lambda_handler.py. The root Terraform module in this repository is meant to be consumed by a separate deployment repository that owns the deployment configuration for a specific AWS account.

Runtime behavior

• Instances are discovered with the configured tag key. By default that key is max_hours_uptime.
• The tag value must be a positive number of hours.
• When the elapsed time since LaunchTime meets or exceeds that value, the Lambda performs the configured action:
  • notify: publish an overdue result and take no EC2 action
  • stop: request StopInstances for overdue running instances
  • terminate: request TerminateInstances for overdue non-terminal instances
• Notification payloads include the instance ID, name, state, launch time, deadline, elapsed hours, configured max hours, and action status.

Terraform interface

The root module exposes project-specific inputs for the runtime contract:

• max_uptime_tag_key
• enforcement_action
• scheduled_lambda_additional_policy_arns

It also injects the required EC2 permissions into the scheduled Lambda role:

• ec2:DescribeInstances
• ec2:StopInstances when enforcement_action = "stop"
• ec2:TerminateInstances when enforcement_action = "terminate"

Example inputs for local interface development are in terraform.tfvars.example, lambda/terraform.tfvars.example, and bootstrap-deploy-repo/terraform.tfvars.example.

Validation

• Python tests: python3 -m unittest discover -s tests -p 'test_*.py' -q
• Terraform/OpenTofu validation:
  • tofu init -backend=false && tofu validate
  • tofu -chdir=lambda init -backend=false && tofu -chdir=lambda validate
  • tofu -chdir=bootstrap-deploy-repo init -backend=false && tofu -chdir=bootstrap-deploy-repo validate

See README-lambdacron.md for the underlying template model and repository structure.