Dynamic Start and Stop Lambda Scheduler Functions

lambda_function.py

import boto3, os, json, time

REGION = os.environ['REGION']
ASG_NAME = os.environ['ASG_NAME']
SSM_PARAMETER_NAME = os.environ['SSM_PARAMETER_NAME']

ssm = boto3.client('ssm', region_name=REGION)
autoscaling = boto3.client('autoscaling', region_name=REGION)
ec2 = boto3.client('ec2', region_name=REGION)
def lambda_handler(event, context):
  # get parameter_store instance id value
  INSTANCE_ID = ssm.get_parameter(Name=SSM_PARAMETER_NAME)['Parameter']['Value']

  # set instance to standby
  autoscaling.enter_standby(
    InstanceIds=[INSTANCE_ID],
    AutoScalingGroupName=ASG_NAME,
    ShouldDecrementDesiredCapacity=True
  )
    
  # wait until LifecycleState is Standby
  response = autoscaling.describe_auto_scaling_instances(
    InstanceIds=[INSTANCE_ID]
  )
    
  while str(json.dumps(response["AutoScalingInstances"][0]["LifecycleState"])).replace('"', '') != "Standby":
    time.sleep(60)
    response = autoscaling.describe_auto_scaling_instances(
      InstanceIds=[INSTANCE_ID]
    )
    
  print('INFO: Instance set to standby...')

  # set desired capacity to 0 to ensure autoscaled instances are cleared
  autoscaling.set_desired_capacity(
      AutoScalingGroupName=ASG_NAME,
      DesiredCapacity=0
  )
  print('INFO: Set desired capacity to 0...')
    
  #stop instance
  ec2.stop_instances(
    InstanceIds=[INSTANCE_ID]
  )
  print('INFO: Stopped ' + INSTANCE_ID)