Add data pull feature to Anonlink Entity Service

Author: Brian Thorne Status: Draft Created: 2020-03-31 Updated: 2020-04-06

Abstract/Purpose

In early 2020 blocking has been added to increase the capacity of the Anonlink system, however the system cannot currently handle users uploading large encoded datasets in a reliable way. Investing in scaling Anonlink to a system that can deal with tens of millions of records vastly increases the chance of adoption and the general usefulness of the system.

When a client tries to upload tens of millions of records today they must have a fast and reliable internet connection and complete in one REST call the entire data upload operation. These uploads can easily be multiple GiB of data.

On the server side we have had to increase default timeouts to >60s to handle the upload of single digit millions of encoded records. The idea of the pull feature is to allow the client to point to a location where the data can be pulled by the server. Modifying the client and API to upload in chunks - making many smaller upload requests - was also considered. This alternative was rejected as we estimate it would take more effort to get to the same reliability. For example the chunking, compression, retrying, and data integrity would all have to be custom handled.

With the Anonlink system we aim to provide everything required to take users from clean records through to an accurate concordance table. We rejected the idea of requiring a data provider to setup their own object store or otherwise hosting their encoded data online; instead we will modify the client to be able to upload to an object store.

Not including the initial design, implementation is expected to be approximately 2 sprints of work for 2 software engineers. The high level objective is that Anonlink be usable to link between datasets that are roughly the size of the Australian population.

The aim of the rest of this document is to specify the design of the "pull data" feature.

The sections are:

• Requirements
• High level system design
• Specifications for implementation (including the REST API).
• decisions and alternatives considered. What would be the "best"/"easiest" approach.

Requirements

• A method for requesting temporary & restricted object store credentials shall be added to the Anonlink Entity Service API. The temporary credentials will authorize the holder to upload data, the credentials must not provide access to any other data providers encodings, or other working data stored in the object store.
• A method for a data provider to provide an object store URI pointing to the encoding data instead of uploading it shall be added to the Anonlink Entity Service API. This method may support pulling directly via http as well.
• A deployment option to expose the MinIO object store via an ingress will be added. As this increases the attack surface an internal security review of MinIO must be conducted. Deployment using default or publicly committed credentials must be mitigated.
• The maximum size of a clients' encodings will be 1TiB.

High Level Design

The Anonlink Entity Service already relies on MinIO (or AWS S3) as an ancillary services for storing encoding data as well as data for in progress computations. MinIO can easily and robustly handle the expected volume of data, and we will leverage the object store to support this pull feature.

At deployment time the user will have the option of exposing the MinIO object store used by the Anonlink Entity Service, or - as already supported - providing external S3/MinIO access credentials. The Anonlink Entity Service's API will be modified such that a data provider can request temporary object store credentials. The client uses these temporary credentials to upload their encodings to the object store. The client then informs the Anonlink server via the clks endpoint of the object store address of the encodings. As per current behaviour, the client would be given an upload token and the normal linkage process continues.

This entire process would all be transparent to the data provider using anonlink-client; internally the client would wrap an S3 or MinIO client library.

Specifications

Rest API

Modification to the upload endpoint

The REST endpoint /projects/{project_id}/clks will be modified to take external data. External data is simply a file stored in an object store. Access credentials are optionally part of the payload to support an external object store, e.g. if the encodings are stored/uploaded to AWS S3.

External data can be one or both of:

• Binary encodings
• Binary blocking info

Each external data component has the same parameters:

• bucket (required) Example "anonlink-uploads"
• file (required)
• endpoint - Object store endpoint: e.g. a public endpoint for a MinIO as part of an Anonlink deployment: minio.anonlink.easd.data61.xyz, or a public (region specific) endpoint for AWS S3: s3.ap-southeast-2.amazonaws.com.
• access_key
• secret_key

The additional schema for the endpoint is designed to become the default. Unlike the current CLKnBlockUpload format the encodings and blocking information is split to allow for easier server side processing.

EncodingUpload:
  description: |
    Object that contains a data provider's encodings including optional blocking information.
    Encodings, blocking information, or both can be provided as an external reference.
  type: object
  required: [encodings]
  properties:
    encodings:
      oneOf:
        - $ref: '#/EncodingArray'
        - $ref: '#/ExternalData'
    blocks:
      oneOf:
        - $ref: '#/BlocksArray'
        - $ref: '#/ExternalData'


ExternalData:
  description: A file in an object store.
  type: object
  required: [file]
  properties:
    credentials:
      type: object
      description: Optional credentials for the object store.
      properties:
        AccessKeyId:
          type: string
        SecretAccessKey:
          type: string
        SessionToken:
          type: string
    file:
      type: object
      required: [bucket, path]
      properties:
        endpoint:
          type: string
        bucket:
          type: string
        path:
          type: string
        

    


 
BlockArray:
  description: Blocking information for encodings. 
  type: array
  items:
    anyOf:
      - type: string
        format: byte
        description: Base64 encoded CLK data
      - type: string
      - type: integer

EncodingArray:
  description: JSON array of encodings. 
  type: array
  items:
    anyOf:
      - type: string
        format: byte
        description: Base64 encoded CLK data
      - type: string
      - type: integer

Addition of an endpoint to retrieve temporary object store credentials

Returns a set of temporary security credentials that the client can use to upload data to the object store.

/authorize-external-upload

The response will contain:

• credentials
  • AccessKeyId (e.g. Y4RJU1RNFGK48LGO9I2S)
  • SecretAccessKey (e.g. sYLRKS1Z7hSjluf6gEbb9066hnx315wHTiACPAjg)
  • Expiration (e.g. 2019-08-08T20:26:12Z
  • SessionToken (e.g. eyJhbGciOiJIUzUxMiIsInR5cCI6IkpXVCJ9.eyJhY2Nlc3NLZXkiOiJZNFJKVTFSTkZHSzQ4TEdPOUkyUyIsImF1ZCI6IlBvRWdYUDZ1Vk80NUlzRU5SbmdEWGo1QXU1WWEiLCJhenAiOiJQb0VnWFA2dVZPNDVJc0VOUm5nRFhqNUF1NVlhIiwiZXhwIjoxNTQxODExMDcxLCJpYXQiOjE1NDE4MDc0NzEsImlzcyI6Imh0dHBzOi8vbG9jYWxob3N0Ojk0NDMvb2F1dGgyL3Rva2VuIiwianRpIjoiYTBiMjc2MjktZWUxYS00M2JmLTg3MzktZjMzNzRhNGNkYmMwIn0.ewHqKVFTaP-j_kgZrcOEKroNUjk10GEp8bqQjxBbYVovV0nHO985VnRESFbcT6XMDDKHZiWqN2vi_ETX_u3Q-w)
• upload
  • endpoint (e.g. minio.anonlink.example.com)
  • bucket (e.g. anonlink-uploads)
  • file (e.g. 2020/05/Z7hSjluf6gEbxxyy.json)

This endpoint may fail if the object store does not support creating temporary credentials. This feature may be entirely disabled in the server configuration, see settings.py and values.yaml.

The temporary credentials must be configured to have a security policy only allowing uploads to a particular bucket for a period of time. The client will not be able to list objects or retrieve objects from this bucket.

An example policy:

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Action": [
        "s3:PutObject"
      ],
      "Effect": "Allow",
      "Resource": [
        "arn:aws:s3:::anonlink-uploads/*"
      ],
      "Sid": "Upload-access-to-specific-bucket-only"
    }
  ]
} 

A possible future extension is to take advantage of MinIO's Security Token Service (STS) to enable clients to request temporary credentials using their existing identity management system.

Relevant links:

• https://github.com/minio/minio/blob/master/docs/sts/assume-role.md
• https://docs.aws.amazon.com/STS/latest/APIReference/API_AssumeRole.html
• https://boto3.amazonaws.com/v1/documentation/api/latest/guide/s3-presigned-urls.html#generating-a-presigned-url-to-upload-a-file
• https://docs.min.io/docs/upload-files-from-browser-using-pre-signed-urls.html

Client Side Specification

The client side implementation will be in anonlink-client, there will be both a public, documented, Python API as well as an implementation via the command line tool.

Uploading will be implemented using either boto3 or MinIO at the implementors discretion.

Progress Handling

The Python api to upload encodings to the object store will be written to support a user supplied callback. See example progress callbacks for Boto3 and MinIO.

The command line interface will use the callback mechanism to display progress using tqdm - already used to show progress during hashing.

Error Handling

Errors during upload detected by the object store client will be caught and raised as an AnonlinkClientError. ResponseError exceptions should be caught and presented to the command line user without a traceback. The object store credentials may be used during a retry attempt. If the object store credentials have expired the client may request new credentials from the Anonlink Entity Service.

Deployment Changes

Extra policy, user, & bucket must be created in MinIO.

Ingress configuration

Proxy The ingress controller may need to be modified to support proxying large uploads through to MinIO.

TLS As MinIO is going to be exposed to the internet it must be protected with a certificate.

https://docs.min.io/docs/generate-let-s-encypt-certificate-using-concert-for-minio.html https://docs.min.io/docs/setup-nginx-proxy-with-minio.html

Security consideration

The user is supplying an object store address - can we trust it? We don't want to pull the wrong data. Misuse could include making our server download illegal data, making our server download terabytes and terabytes of data.

If using our own object store we can dictate the bucket and file, but we want to support an external object store too.

Additional Considerations (WIP)

Initially we will support pulling from an S3 like object store. How about direct HTTP/both? Is FTP still common? Do we support pulling data via HTTP (e.g. someone gives the server a Google Drive or dropbox URL we could pull the data).

Monitoring progress during pulling data, resuming pulling data, identifying and dealing with data corruption, service failure.

Should the entity service deploy a separate publicly available object store, or expose the one it uses internally?

Authentication/presigned urls? Presigned URLs are usually used with non object store clients - enabling direct POST/GET calls. Need to determine if object store clients can use them to take advantage of chunked uploads, integrity checking etc. See https://github.com/minio/minio/blob/master/docs/sts/assume-role.md and https://boto3.amazonaws.com/v1/documentation/api/latest/guide/s3-presigned-urls.html#using-presigned-urls-to-perform-other-s3-operations

Ability to easily copy from one object store to another? MinIO has a sync

Configuration of client tool - ~/.anonlinkcfg

Notification of an upload by MinIO into Redis or Postgres is possible. We decided it was not worth the extra complexity as the client will be uploading via our tool so the client is in a good position to reliably inform the server when the upload is complete. See the MinIO bucket notification guide.

What if the object changes or is deleted while we are pulling it?

Anything else?