S3 File Upload + Python

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This tutorial will cover using python to upload files to AWS S3 programatically. This can be used in conjunction with TODO INSERT LINK HERE to programatically upload files to a website hosted in AWS S3.


This tutorial assumes you have an AWS account established.


About S3

You will be using Amazon S3 (Simple Storage Service) as a location to upload files to the cloud. You can read more about S3 here.

S3 is essentially a cloud file storage service. Typical use cases might include:

  • File storage for access by other AWS services
  • Storage of data files (i.e. .csv, .tsv, .txt) which you might want to process in the cloud or share amongst computers
  • Storing AWS log data or other data outputted from AWS services
  • As a collection of files referenced on a website (i.e. image or font hosting), like a CDN.

We will set up a bucket which will be used to as the location to which we must upload our files, and then use the Boto3 python library, along with an IAM profile to upload files to that bucket.

Setting up IAM roles

This tutorial assumes you have an AWS account already. If you do not, go ahead and create an AWS account here

First, we need to set up an IAM profile. This is to get access to credentials which will allow you access to your site to upload files.

Log in to AWS and navigate to Services >Security, Identity, and Compliance> IAM


In the left side panel, click on Users

Then click Add User

Now we will set up our IAM role.

First, define a username. This user’s access will be restricted to uploading files to s3, so this tutorial will use s3-upload

Since you will be uploading files programatically, under Select AWS access type choose Programatic access.

Ensure your user details are similiar to the following and click Next.


Now, you must grant our user access to a set of permissions. If desired, you can associate your user with a group and assign permissions to the group (which would be useful if you wanted to have several users uploading to s3), however in this instance this tutorial will attach policies directly.

Click on Attach existing policies directly, and then in the table find and select AmazonS3FullAccess.

Ensure your screen looks like the following and then click Next.


Review your user is configured as specified and click Create user.

You will now be presented with three pieces of information: your User Name, your Access key ID, and your Secret access key. Copy these down and click close.

NOTE: you should NEVER publicly reveal your Access key ID or Secret access key, on Github or anywhere else. An IAM role is granting access to your AWS account, and if your IAM role has been given enough permissions people can easily hack your account and create enormous charges under your name. If a credential breach is suspected, credentials should IMMEDIATELY be invalidated. There has been fraudulent AWS activity in this class which has nearly cost a group $7200. Please keep your credentials secure.

Finally, click on your newly created user in the Users table, and copy down the USER ARN.

Now that your IAM profile is set up, you will establish your S3 bucket.

Setting up the bucket

Please note, if you plan to use this tutorial to upload files to an S3 website programatically, you should first follow the Website with AWS S3 tutorial then come back to this tutorial.

Navigate to Services>Storage>S3


Click on create bucket.

You will then need to configure the bucket settings.

  • Select a bucket name. This must be unique across all buckets in S3. This tutorial will use ese205-tutorial-bucket as a bucket name.

Ignore the rest of the settings on this view and click next.

This is the Configure Options tab. All the settings here are irrelevant for now, so just click next.

Now you must set bucket permissions. Permissions should be as follows:

  • The bucket OWNER should have both Read and Write access. This should be default behavior.

Click next.

In the review tab, verify everything is correct, especially that you have a Bucket name that you like, then click Create Bucket.

Congragulations, you’ve set up your first S3 bucket!

There’s have one more step before you can upload files to your bucket.

Open up your bucket by clicking on its name in the Buckets table.

Navigate to the Permissions tab, and click on Bucket Policy.

Then, paste the following code, being sure to replace your-bucket-name with your bucket name, and user-arn with your IAM user’s ARN.

Note, if you are uploading to a Website hosted with S3 as in the Website with AWS S3 tutorial, you should simply append the policy within Statement to your current array of Statements
    "Version": "2012-10-17",
    "Statement": [
            "Effect": "Allow",
            "Principal": {
                "AWS": "user-arn"
            "Action": "s3:PutObject",
            "Resource": "arn:aws:s3:::your-bucket-name/*"

Be sure to click Save.

What you have just done is granted PutObject permissions to your IAM user for this specific bucket.

Uploading Files

Now you’ll upload your files.

You’ll need both Python and Boto3 installed. Boto3 is the python package you use for interfacing with AWS, and can be installed with pip install boto3.

Then, you can upload your files. The code to do so is as follows:

import boto3
# Create a Boto3 session obejct with your IAM user credentials
session = boto3.Session(
# Ensure the region name matches the region of your bucket. us-east-1 matches US East (N. Virginia)
s3 = session.resource('s3', region_name='us-east-1')
# Replace bucket-name with your bucket name, as well as the name of the file you want displayed in your bucket, including the extension
object = s3.Object('bucket-name', 'file-name-for-bucket.extension')
# Put your local file into the bucket by replacing the path-to-local-file with your desired file to upload, including the file extension
object.put(Body=open('path-to-local-file.extension', 'rb'))

Now if you refresh your S3 bucket, you should see your uploaded file!


Ethan Shry, Fall 2018

Group Link


External References