AWS Lambda /tmp python script import module error - amazon-web-services

Question

I am trying to run a python script that is present in AWS Lambda /tmp directory. The scripts require some extra dependencies like boto3 etc to run the file. When AWS Lambda runs the file it gives out the following error:
ModuleNotFoundError: No module named 'boto3'
However when i run this file directly as a lambda function then it runs easily whithout any import errors.
The Lambda Code that is trying to execute the code present in /tmp directory :
import json
import os
import urllib.parse
import boto3
s3 = boto3.client('s3')
def lambda_handler(event, context):
records = [x for x in event.get('Records', []) if x.get('eventName') == 'ObjectCreated:Put']
sorted_events = sorted(records, key=lambda e: e.get('eventTime'))
latest_event = sorted_events[-1] if sorted_events else {}
info = latest_event.get('s3', {})
file_key = info.get('object', {}).get('key')
bucket_name = info.get('bucket', {}).get('name')
s3 = boto3.resource('s3')
BUCKET_NAME = bucket_name
keys = [file_key]
for KEY in keys:
local_file_name = '/tmp/'+KEY
s3.Bucket(BUCKET_NAME).download_file(KEY, local_file_name)
print("Running Incoming File !! ")
os.system('python ' + local_file_name)
The /tmp code that is trying to get some data from S3 using boto3 :
import sys
import boto3
import json
def main():
session = boto3.Session(
aws_access_key_id='##',
aws_secret_access_key='##',
region_name='##')
s3 = session.resource('s3')
# get a handle on the bucket that holds your file
bucket = s3.Bucket('##')
# get a handle on the object you want (i.e. your file)
obj = bucket.Object(key='8.json')
# get the object
response = obj.get()
# read the contents of the file
lines = response['Body'].read().decode()
data = json.loads(lines)
transactions = data['dataset']['fields']
print(str(len(transactions)))
return str(len(transactions))
main()
So boto3 is imported in both the codes . But its only successful when the lambda code is executing it . However /tmp code cant import boto3 .
What can be the reason and how can i resolve it ?

Answer 1

Executing another python process does not copy Lambda's PYTHONPATH by default:
os.system('python ' + local_file_name)
Rewrite like this:
os.system('PYTHONPATH=/var/runtime python ' + local_file_name)
In order to find out complete PYTHONPATH the current Lambda version is using, add the following to the first script (one executed by Lambda):
import sys
print(sys.path)