How to set bucket CORS configuration

Cross Origin Resource Sharing (CORS) enables client web applications in one domain to access resources in another domain. An S3 bucket can be configured to enable cross-origin requests. The configuration defines rules that specify the allowed origins, HTTP methods (GET, PUT, etc.), and other elements.

Prerequisites:

• Fuga Cloud EC2 credentials
• Python 3.6+
• boto3 python package (tested with boto3 1.9.244 and botocore 1.12.244)

Create a new Python file named add-cors-configuration.py with the following content:

#!/usr/bin/env python3

import os
import sys
import json
from argparse import ArgumentParser
from urllib.parse import urlencode, quote_plus

import boto3

with open('credentials.json', 'r') as fd:
    credentials = json.loads(fd.read())

def main():

    parser = ArgumentParser(description='set bucket CORS configuration')
    parser.add_argument('--bucket-name',
                        dest='bucket_name',
                        action='store',
                        required=True,
                        help='name of the bucket')
    parser.add_argument('--cors-config',
                        dest='cors_config_path',
                        action='store',
                        required=True,
                        help='path to CORS configuration')
    args = parser.parse_args()

    s3 = boto3.client('s3',
        endpoint_url=credentials.get('endpoint_url'),
        aws_access_key_id=credentials.get('access_key'),
        aws_secret_access_key=credentials.get('secret_key'),
    )

    with open(args.cors_config_path, 'r') as fd:
        cors_configuration = json.loads(fd.read())

    response = s3.put_bucket_cors(Bucket=args.bucket_name,
       CORSConfiguration=cors_configuration)

    response = s3.get_bucket_cors(Bucket=args.bucket_name)
    print(json.dumps(response['CORSRules'], indent=2))


if __name__ == '__main__':
    main()

Create a new JSON file named cors.json with the following content, update the contents to match your setup:

{
  "CORSRules": [
    {
      "AllowedHeaders": [
        "Authorization"
      ],
      "AllowedMethods": [
        "GET",
        "PUT"
      ],
      "AllowedOrigins": [
        "*"
      ],
      "ExposeHeaders": [
        "GET",
        "PUT"
      ],
      "MaxAgeSeconds": 3000
    }
  ]
}

Create a new JSON file named credentials.json with the following content, update the contents to match your setup, you can find the endpoints in my.fuga dashboard.

{
  "access_key": "<your ec2 credential access>",
  "secret_key": "<your ec2 credential secret>",
  "endpoint_url": "<api_endpoints>"
}

Install required Python packages and run the script to set CORS configuration:

% pip install --user boto3
% python3.7 ./add_cors_configuration.py --bucket-name my-first-bucket --cors-config ./cors.json
{
  "CORSRules": [
    {
      "AllowedHeaders": [
        "Authorization"
      ],
      "AllowedMethods": [
        "GET",
        "PUT"
      ],
      "AllowedOrigins": [
        "*"
      ],
      "ExposeHeaders": [
        "GET",
        "PUT"
      ],
      "MaxAgeSeconds": 3000
    }
  ]
}

For information and examples see boto3.amazonaws.com.