EBS volume attached on running instance lambda logic required - amazon-web-services

Question

I have written a Lambda function which can be trigged only when an EBS volume is attached to running instance and the status is completed. If this condition is true, then the below Lambda function will trigger and mounting the two EBS devices on my running OS.
Is this possible with a Lambda function or not? Please help me with the below code. My two EBS volumes are created and attached with a CloudFormation template.
from __future__ import print_function
import boto3
import os
ec2 = boto3.client('ec2')
def lambda_handler(event, context):
volume =(event['resources'][0].split('/')[1])
if event['detail']['result'] == 'completed':
attach=ec2.describe_volumes(VolumeIds=[volume])['Volumes'][0]['Attachments']
if attach:
instance = attach[0]['InstanceId']
if instance:
os.system('mkfs -t ext4 /dev/xvdg')
os.system('mkfs -t ext4 /dev/xvdf')
os.system('mkdir -p /var/www/production /var/lib/SQL')
os.system('mount /dev/xvdf /var/www/production')
os.system('mount /dev/xvdg /var/lib/SQL')
os.system('echo dev/xvdf /var/www/production ext4 defaults,nofail 0 2 >> /etc/fstab')
os.system('echo /dev/xvdg /var/lib/SQL ext4 defaults,nofail 0 2 >> /etc/fstab')
else:
raise Exception('Volume ' + volume + ' not currently attached to an instance')

Answer 1

Rohan,
Without some magic, Lambda cannot execute commands on EC2 instances.
I am assuming that you are creating new EC2 instances using CloudFormation and attaching the EBS volumes at that time.
You can put your OS level commands into the UserData under Resources in CloudFormation.
This link has examples:
Deploying Applications on Amazon EC2 with AWS CloudFormation