EC2 Cost Optimization Using AWS Lambda Function

Using the lambda function with python code, we will be able to shut down the EC2-instances automatically. The python code that can be executed automatically using the AWS cloudwatch rules has been provided below.

General Information

To save costs on AWS EC2, it may be necessary in some cases to automatically shut down EC2 instances during off-peak hours. For example, if the developers have a few EC2 instances running, we can automatically shut them down during their non-working hours using lambda functions and cloudwatch rules.

Technology Used

• AWS Lambda
• AWS Cloudwatch

About the python code

The python codes added below will stop and start all ec2-instances every day at 12:15 AM GMT and 08:15 AM GMT respectively with instance tags key: “env” and value: “testing”

The python code has been written below::

1. To Stop the Instance

import boto3

REGION = "ap-south-1"

def lambda_handler(event, context):
    
  ec2 = boto3.client('ec2',region_name=REGION)

  all_ec2 = ec2.describe_instances(
      
      Filters=[
        {'Name':'tag:env', 'Values':["testing"]}
      ]
  )

  for instance in all_ec2['Reservations'][0]['Instances']:
    
    print("Stopping Ec2 : {} ".format( instance['InstanceId'] ))
    
    ec2.stop_instances(InstanceIds=[ instance['InstanceId'] ])

2. To Start the Instance

import boto3

REGION = "ap-south-1"

def lambda_handler(event, context):
    
  ec2 = boto3.client('ec2',region_name=REGION)

  all_ec2 = ec2.describe_instances(
      
      Filters=[
        {'Name':'tag:env', 'Values':["testing"]}
      ]
  )

  for instance in all_ec2['Reservations'][0]['Instances']:
    
    print("Starting Ec2 : {} ".format( instance['InstanceId'] ))
    
    ec2.start_instances(InstanceIds=[ instance['InstanceId'] ])

Steps to be done::

1. Create an IAM role granting EC2 Full access to Lambda

Create the IAM role by selecting the AWS Service — Lambda

Grant EC2 Full access to Lambda

2. Create Lambda Function with both the start and stop EC2 Python Codes

Create the Lambda Function

Add the python code to stop/start the instance in separate lambda functions

Check the added lambda functions

3. Create the cloudwatch rules to automatically run the lambda function

Cloudwatch rule to stop the ec2-instances at 12:15 AM GMT every day

Cloudwatch rule to start the ec2-instances at 08:15 AM GMT every day

Check the Cloudwatch rules

Result:

The Cloudwatch rules will execute the python codes added in the Lambda functions and it will stop and start all ec2-instances every day at 12:15 AM GMT and 08:15 AM GMT respectively with the instance tags key: “env” and value: “testing”

Author:

Created by @sebinxavi — feel free to contact me and advise as necessary!