Lambda function for starting an already set EC2 instance and ssh-ing into it using Paramiko library.

aws-lambda-start-ssh.py

"""
Lambda function for starting an already set EC2 instance and ssh-ing into it using Paramiko library. 
Paramiko is installed on lambda using lambda layers. 
"""

import json
import paramiko
import boto3

region = ''
ec2 = boto3.resource('ec2', region_name = region)
s3_client = boto3.client('s3')

def start_instance(id):
    ec2 = boto3.client('ec2')
    response = ec2.start_instances(InstanceIds=[id], DryRun = False)
    return response

  
def get_ip_from_instance(id):
    instance = None
    for i in ec2.instances.all():
        if i.id == id:
            instance = i
            print(i)
            
    if instance.state.get('Name')!='running':
        print(instance.state.get('Name'))
        # print(instance.id)
        start_instance(instance.id)
        instance.wait_until_running()
    instance.load()
    return instance.public_ip_address


def lambda_handler(event, context):
    # TODO implement
    instance_id = ''            # Instance id of ec2 instance
    
    ip = get_ip_from_instance(instance_id)
    print(ip)
    
    bucket_name = ''            # S3 bucket where .pem file is stored
    file_name = ''              # filename of .pem file
    s3_client.download_file(bucket_name, file_name, f'/tmp/{file_name}') 
    key = paramiko.RSAKey.from_private_key_file(f"/tmp/{file_name}")
   
    ssh_client = paramiko.SSHClient()
    ssh_client.set_missing_host_key_policy(paramiko.AutoAddPolicy())

    host=ip
    print("Connecting to : " + host)
    # connecting to server
    ssh_client.connect(hostname=host, username="ubuntu", pkey=key)
    print("Connected to :" + host)

    return {
        'statusCode': 200,
        'body': json.dumps('Hello from Lambda!')
    }