error "read only file system" when I'm trying to create file using bash script in AWS Lambda function (python)

Question

I have python (3.8) Lambda function that connected to EFS, in mount /mnt/my-mount.

I want to run a bash script via the function, so I created another file script.sh.

This is the python function:

import json
import os

def lambda_handler(event, context):
    os.system("sh script.sh")

and bash script script.sh:

#!/bin/bash
touch hello.txt

and I get the following error:

cannot touch script.sh: Read-only file system

Notes:

I can create file using the python function (f.write).
If I run os.system("chmod 777 a.sh"), again I get Read-Only file system.
If I use rc = subprocess.call("bash a.sh"), I get No such file or directory: 'bash a.sh'
The EFS has access point for user 1000:1000 with 777 permissions.

Do you need to specify an absolute path such as touch /mnt/my-mount/hello.txt? — jarmod
– jarmod, Commented Sep 25, 2020 at 15:21

Bitconym · Accepted Answer · 2021-07-30 09:59:26Z

2

This could be due to having the Lambda role without proper write permissions. You should attach the proper policy or define your custom one:

answered Jul 30, 2021 at 9:59

Bitconym

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Comments

rraj gautam · Accepted Answer · 2023-10-10 10:38:24Z

0

Along with the permission, the issue will be with directory path of Access Point. If you are mounting it in lambda, the root directory path "/" will give permission denied issue. So, make sure you use some other absolute path other than default "/".

Access Point Configuration

Lambda Configuration

answered Oct 10, 2023 at 10:38

rraj gautam

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