Uploading a file to a S3 bucket with a prefix using Boto3

import boto3

s3 = boto3.resource('s3')
s3.meta.client.upload_file( 'csv1.csv', "bucketname", "prefixna/csv1.csv")

I'm assuming you have all this set up:

1. AWS Access Key ID and Secret Key set up (typically stored at ~/.aws/credentials
2. You have access to S3 and you know your bucket names & prefixes (subdirectories)

According to the Boto3 S3 upload_file documentation, you should upload your upload like this:

upload_file(Filename, Bucket, Key, ExtraArgs=None, Callback=None, Config=None)

import boto3
s3 = boto3.resource('s3')
s3.meta.client.upload_file('/tmp/hello.txt', 'mybucket', 'hello.txt')

The key to note here is s3.meta.client. Don't forget that--it worked for me!

I hope that helped.

Turns out I needed SSE:

transfer = S3Transfer(s3_client)
transfer.upload_file('/tmp/hello.txt', bucket_name, prefix+'hello-remote.txt', extra_args={'ServerSideEncryption': "AES256"})