Fork of AWS proxy module

WARNING: Not Expecting this to be merged to the main anomalizer/ngx_aws_auth branch. We have modded it to serve our use case and decided to share the ideas.

This module is based on Open SSL 1.1.1. So works with nginx 1.19.1.

Tested with nginx 1.19.1.

This nginx module can proxy requests to authenticated S3 backends using Amazon's V4 authentication API. The first version of this module was written for the V2 authentication protocol and can be found in the AuthV2 branch.

License

This project uses the same license as ngnix does i.e. the 2 clause BSD / simplified BSD / FreeBSD license

Usage example

Implements proxying of authenticated requests to S3.

  server {
    listen     8000;

    aws_access_key your_aws_access_key; # Example AKIDEXAMPLE
    aws_secret_key your_aws_secret_key; #Example L4vRLWAO92X5L3Sqk5QydUSdB0nC9+1wfqLMOKLbRp4=
    aws_region eu-west-2;
    aws_service s3;
    aws_s3_bucket your_s3_bucket;

    location / {
      aws_sign;
      proxy_pass http://your_s3_bucket.s3.amazonaws.com;
    }

    # This is an example that does not use the server root for the proxy root
    location /myfiles {

      rewrite /myfiles/(.*) /$1 break;
      proxy_pass http://your_s3_bucket.s3.amazonaws.com/$1;

      aws_access_key your_aws_access_key;
      aws_secret_key your_aws_secret_key; #Example L4vRLWAO92X5L3Sqk5QydUSdB0nC9+1wfqLMOKLbRp4=
      aws_region eu-west-2;
      aws_service s3;
    }

    # This is an example that use specific s3 endpoint, default endpoint is s3.amazonaws.com
    location /s3_beijing {

      rewrite /s3_beijing/(.*) /$1 break;
      proxy_pass http://your_s3_bucket.s3.cn-north-1.amazonaws.com.cn/$1;

      aws_sign;
      aws_endpoint "s3.cn-north-1.amazonaws.com.cn";
      aws_access_key your_aws_access_key;
      aws_secret_key your_aws_secret_key; #Example L4vRLWAO92X5L3Sqk5QydUSdB0nC9+1wfqLMOKLbRp4=
      aws_region eu-west-2;
      aws_service s3;
    }
  }

Security considerations

The V4 protocol does not need access to the actual secret keys that one obtains from the IAM service. The correct way to use the IAM key is to actually generate a scoped signing key and use this signing key to access S3. This nginx module requires the signing key and not the actual secret key. It is an insecure practise to let the secret key reside on your nginx server. (So true use this branch at your own risk!!!)

Note that signing keys have a validity of just one week. Hence, they need to be refreshed constantly. Please useyour favourite configuration management system such as saltstack, puppet, chef, etc. etc. to distribute the signing keys to your nginx clusters. Do not forget to HUP the server after placing the new signing key as nginx reads the configuration only at startup time.

A standalone python script has been provided to generate the signing key

./generate_signing_key -h
usage: generate_signing_key [-h] -k SECRET_KEY -r REGION [-s SERVICE]
                            [-d DATE] [--no-base64] [-v]

Generate AWS S3 signing key in it's base64 encoded form

optional arguments:
  -h, --help            show this help message and exit
  -k SECRET_KEY, --secret-key SECRET_KEY
                        The secret key generated using AWS IAM. Do not confuse
                        this with the access key id
  -r REGION, --region REGION
                        The AWS region where this key would be used. Example:
                        us-east-1
  -s SERVICE, --service SERVICE
                        The AWS service for which this key would be used.
                        Example: s3
  -d DATE, --date DATE  The date on which this key is generated in yyyymmdd
                        format
  --no-base64           Disable output as a base64 encoded string. This NOT
                        recommended
  -v, --verbose         Produce verbose output on stderr


./generate_signing_key -k wJalrXUtnFEMI/K7MDENG+bPxRfiCYEXAMPLEKEY -r us-east-1
L4vRLWAO92X5L3Sqk5QydUSdB0nC9+1wfqLMOKLbRp4=
20160902/us-east-1/s3/aws4_request

Known limitations

The 2.x version of the module currently only has support for GET and HEAD calls. This is because signing request body is complex and has not yet been implemented.

Credits

Original idea based on http://nginx.org/pipermail/nginx/2010-February/018583.html and suggestion of moving to variables rather than patching the proxy module.

Subsequent contributions can be found in the commit logs of the project.