lambda function to sftp files from s3 to anywhere else

lambda_sftp.py

import boto3                                                                                                                 
import os                                                                                                                    
import paramiko      

#
# use a trigger to copy files from s3 to an on premise server
#
# TODO: 
#   configuration using lambda environment vars
#
                                                                                                                             
def worker_handler(event, context):                                                                                          
                                                                                                                             
    sourceKey = event['Records'][0]['s3']['object']['key']                                                                   
    sourceFile = os.path.basename(sourceKey)                                                                                 
    print("sourceKey = " + sourceKey + "\nsourceFile = " + sourceFile)                                                       
                                                                                                                             
    s3_client = boto3.client('s3')                                                                                           
    #s3_client.download_file('BUCKET_NAME','PATH/TO/YOUR/SOURCE/FILE','/PATH/TO/DESTINATION/FILE')                           
    s3_client.download_file('my-magic-bucket','lambda-sftp/req/sshkey.pem','/tmp/sshkey.pem')
    s3_client.download_file('my-magic-bucket',sourceKey,'/tmp/' + sourceFile)                                        
                                                                                                                             
    k = paramiko.RSAKey.from_private_key_file("/tmp/sshkey.pem")                                                            
    c = paramiko.SSHClient()                                                                                                 
    c.set_missing_host_key_policy(paramiko.AutoAddPolicy())                                                                  
                                                                                                                             
    host='111.222.333.444'                                                                                                      
    print("Connecting to " + host)                                                                                           
    c.connect( hostname = host, username = "myusername", pkey = k )                                                          
    print("Connected to " + host)                                                                                            
                                                                                                                             
    ftp_client=c.open_sftp()                                                                                                 
    print("uploading " + sourceFile)                                                                                         
    # ftp_client.put('/path/to/source/file','/path/to/destination/file/on/remote/server')                                    
    ftp_client.put('/tmp/' + sourceFile,'/home/myusername/' + sourceFile)                               
    print("uploaded " + sourceFile)                                                                                          
    ftp_client.close()                                                                                                       
                                                                                                                             
    return                                                                                                                   
    {                                                                                                                        
        'message' : "Script execution completed. See Cloudwatch logs for complete output"                                    
    }