Boto s3 permission issue - django

Question

I've come across very weird permission issue. I'm trying to upload a file to s3, here's my function
def UploadFile(FileName, S3FileName):
session = boto3.session.Session()
s3 = session.resource('s3')
s3.meta.client.upload_file(FileName, "MyBucketName", S3FileName)
I did configure aws-cli on the server. This function works fine when I log into server and launch python interpreter but fails when called from my django rest api with:
An error occurred (AccessDenied) when calling the PutObject operation: Access Denied
No idea why the same function works when called from interpreter and fails when called from django. Both are in the same virtual environment. Any suggestions?

Answer 1

According to the boto3 docs, boto3 is looking for credentials in the following places:
Passing credentials as parameters in the boto.client() method
Passing credentials as parameters when creating a Session object
Environment variables
Shared credential file (~/.aws/credentials)
AWS config file (~/.aws/config)
Assume Role provider
Boto2 config file (/etc/boto.cfg and ~/.boto)
Instance metadata service on an Amazon EC2 instance that has an IAM role configured.
Note that many of these places are paths with "~" in them. "~" refers to the current user's home directory. Most likely, your REST API is running under a different system user than you are using to test your code.
The proper solution is to use IAM roles, as this allows your server to have S3 access without you needing to give it IAM credentials. However, if that doesn't work for your setup, you should put the IAM credentials in the /etc/boto.cfg file as that is user agnostic.