Custom URL Signer

Introduction

Custom media URL regeneration may be added for greater security and permission control.

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  • This is an optional feature. Baseline generation is reasonably secure for many cases. If you are just looking for a baseline connection you can ignore this.
  • See individual connection pages for storage permission requirements, this document is only for custom URL signer related information.

Warnings

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Performance

Using a custom signer may impact end user performance.
If you are experience performance issues and believe it's not from the signer, please see Optimize

AWS

S3 Connections can receive a custom URL signer service.

  • By default we do a GET request to the provided URL in the connection configuration.
  • If the installation has OAUTH2 enabled, it will send the JWT in the Authorization header. Otherwise it will send the session ID cookie.
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The parameters of the bucket name and path name are appended in the following order:

'{url_signer_service_base_url}/{bucket_name}/?key={blob_name_encoded}'

blob_name_encoded corresponds to the full s3 key of the blob and is url-encoded.

API Reference

from_blob_path

Signed URL Caching and Expiry Times

There are 2 Env variables you can use to modify the cache time renewal:

  • SIGNED_URL_CACHE_MINIMUM_SECONDS_VALID: Controls how many seconds we want to keep the cached URL's cached in a valid state. (Must be less than your Storage provider URL expiry time)
  • SIGNED_URL_CACHE_NEW_OFFSET_SECONDS_VALID: Controls how many seconds we want a new URL to be valid after being regenerated.

For example if I set SIGNED_URL_CACHE_MINIMUM_DAYS_VALID to 18,000 (5 days) and SIGNED_URL_CACHE_NEW_OFFSET_DAYS_VALID to 21,600 (6 days). I will guarantee that my urls will be re-generated 1 day before expiry. This can help when generating JSON exports to have a big enough buffer of time to work with the signed URLs generated on the JSON export before they expire.

This also means that we need to configure SIGNED_URL_CACHE_MINIMUM_SECONDS_VALID to always be greater than SIGNED_URL_CACHE_NEW_OFFSET_SECONDS_VALID. Otherwise the urls will be regenerated always and there will be no actual cache in place.