Using Python Boto3 and Lambda functions to start/stop EC2 Instances Based on Tags

4 min readOct 29, 2022

In this blog we have to create script to start/stop ec2 instances using python script based on tags, to launch instances check here.

Prerequisites

An AWS Account with An IAM User with IAM, Lambda, EC2 Access

Create new role for our lambda functions.

Let’s name role name as lambda-ec2-access, above policy gives access to instances which contains auto-start-stop: Yes tags.

Launch EC2 instances

Launch instances and add tags, if instances already exists just add auto-start-stop: Yes tags to instances.

Create Two Lambda Functions To Start/Stop EC2 Instances Based On Tags

stop-ec2-instances

Goto Lambda console and click on create function
Create lambda functions with stop-ec2-instance, python3.8 runtime, and lambda-ec2-access role.

Goto code editor and start writing the code.

import boto3 and json modules.

import json
import boto3

Lets invoke resource for EC2 along with the region name where we are going to perform this activity.

ec2 = boto3.resource('ec2', region_name='ap-south-1')

First search for instance which are in running state and are having auto-start-stop tag as “Yes” by using instances.filter(). Checkout he official documentation for this method here

def lambda_handler(event, context):
 instances = ec2.instances.filter(Filters=[{'Name': 'instance-state-name', 'Values': ['running']},{'Name': 'tag:auto-start-stop','Values':['Yes']}])

List returned using for loop and fetch instance ids and save it in variable id.

def lambda_handler(event, context):
instances = ec2.instances.filter(Filters=[{'Name': 'instance-state-name', 'Values': ['running']},{'Name': 'tag:auto-start-stop','Values':['Yes']}])
for instance in instances:
    id=instance.id

Stopping instances given a list of instance IDs filtering. This will stop all running instances having auto-start-stop tag with value as Yes.

def lambda_handler(event, context):
 instances = ec2.instances.filter(Filters=[{'Name': 'instance-state-name', 'Values': ['running']},{'Name': 'tag:Env','Values':['Dev']}])
 for instance in instances:
     id=instance.id
     ec2.instances.filter(InstanceIds=[id]).stop()
     print("Instance ID is stopped:- "+instance.id)
 return "success"

To view entire stop-ec2-instances code

start-ec2-instances

Goto Lambda console and click on create function
Create lambda functions with start-ec2-instance, python3.8 runtime, and lambda-ec2-access role.

Goto code editor and start writing the code.

import boto3 and json modules.

import json
import boto3

Lets invoke resource for EC2 along with the region name where we are going to perform this activity.

ec2 = boto3.resource('ec2', region_name='ap-south-1')

First search for instance which are in stopped state and are having auto-start-stop tag as “Yes” by using instances.filter(). Checkout he official documentation for this method here

def lambda_handler(event, context):
 instances = ec2.instances.filter(Filters=[{'Name': 'instance-state-name', 'Values': ['stopped']},{'Name': 'tag:auto-start-stop','Values':['Yes']}])

List returned using for loop and fetch instance ids and save it in variable id.

def lambda_handler(event, context):
instances = ec2.instances.filter(Filters=[{'Name': 'instance-state-name', 'Values': ['stopped']},{'Name': 'tag:auto-start-stop','Values':['Yes']}])
for instance in instances:
    id=instance.id

Stopping instances given a list of instance IDs filtering. This will start all stopped instances having auto-start-stop tag with value as Yes.

def lambda_handler(event, context):
 instances = ec2.instances.filter(Filters=[{'Name': 'instance-state-name', 'Values': ['stopped']},{'Name': 'tag:Env','Values':['Dev']}])
 for instance in instances:
     id=instance.id
     ec2.instances.filter(InstanceIds=[id]).stop()
     print("Instance ID is stopped:- "+instance.id)
 return "success"

To view entire start-ec2-instances code

Once lambda functions created trigger them, it will start or stop instances based on instance state. Or can take this setup up cron jobs to run on specific time using Eventbridge, Jenkins, crontab etc.

Resource clean up

Terminate EC2 instances
Delete Lambda functions for start and stop
Delete Lambda Role

Conclusion

Boto3 provided inbuild methods for AWS resources using which many task can be automated by writing a python script.

Stay tuned for my next blog…..

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