Python-AWS Lambda不等待子流程完成

Question

I'm trying to execute the following code on AWS lambda:

from os import listdir
from subprocess import call
from datetime import datetime

def lambda_handler(event, context):
    print(datetime.now())
    call('sh scp.sh', shell=True)
    print(listdir('/tmp/stores'))
    print(datetime.now())

The scp.sh script execute a copy files from other server, but the problem is, the main thread is not waiting for the subprocess finishes.

This is the output:

START RequestId: 6241a143-8c5f-11e8-9d42-d330bf352385 Version: $LATEST
2018-07-20 20:56:33.568496
[Errno 2] No such file or directory: '/tmp/stores': FileNotFoundError
Traceback (most recent call last):
  File "/var/task/main.py", line 8, in lambda_handler
    print(listdir('/tmp/stores'))
FileNotFoundError: [Errno 2] No such file or directory: '/tmp/stores'

This is the source of scp.sh file:

ssh-add nextcloud-key.pem;
scp -r ubuntu@34.218.106.211:/tmp/stores /tmp/stores;

Why this is happening?

Answer 1

What's happening is that the scp command is failing and nothing gets copied to /tmp. Instead of subprocess.call , use subprocess.check_call and you'll see that it raises an exception.