Regularly Terminate AWS instances that are idle(<5% CPU Utilization) for the past 10 minutes

aws_terminator.py

import json
import subprocess
import pendulum  # pip install pendulum

# Note: This is a hacky, quick solution prototyped in less than an hour, the ideal solution would involve using boto3 and other best practices auth

# ensure that your AWS CLI is configured and has the keys and default region set up. This script works in the default region

instance_cmd = """
aws ec2 describe-instances \
    --filters "Name=tag-key,Values=Name" "Name=instance-state-name,Values=running"\
    --query 'Reservations[*].Instances[*].{Instance:InstanceId,AZ:Placement.AvailabilityZone,Name:Tags[?Key==`Name`]|[0].Value}' \
    --output json
"""
instances = subprocess.check_output(instance_cmd, shell=True)
try:
    instances = json.loads(instances)
except:
    print(instances)
    exit()

ids = [k[0]["Instance"] for k in instances]

endtime = pendulum.now().utcnow()
starttime = endtime.subtract(minutes=10)

idle_instances = []

print(pendulum.now().to_datetime_string())
print("----------------------------------------------------------------")
for id in ids:
    cloudwatch_cmd = f"""aws cloudwatch get-metric-statistics --namespace AWS/EC2 --metric-name CPUUtilization  --period 3600 \
    --statistics Average --dimensions Name=InstanceId,Value={id} --start-time {starttime.to_iso8601_string()} --end-time {endtime.to_iso8601_string()} \
    --output json
    """
    res = subprocess.check_output(cloudwatch_cmd, shell=True)
    res = json.loads(res)
    avg_util = res["Datapoints"][0]["Average"]
    print(id, avg_util)
    if avg_util < 5:
        idle_instances.append(id)

if len(idle_instances) > 0:
    print(idle_instances)
    terminate_cmd = f"aws ec2 terminate-instances --instance-ids {' '.join(idle_instances)} --output text"
    print(terminate_cmd)
    print(str(subprocess.check_output(terminate_cmd, shell=True)))
    print(f"Terminated {len(idle_instances)}")
print("----------------------------------------------------------------")

# Example CRON Tab command to run this script regularly (the below command runs this script every 15 mins)
# */15 * * * * python /home/ubuntu/aws_terminator.py >> ~/aws_terminator.log