Purge cached copies when a file is deleted or removed

How to do it

A CDN keeps serving its cached copy until it expires, and a versioned file may be cached for a year. An erased photo or a removed infringing video then stays online. GDPR Article 17 asks for erasure without undue delay. Article 6 of the Digital Services Act keeps a host free of liability only if it removes illegal content expeditiously once it knows. Tag every cached response with its file ID, such as a cache tag or surrogate key, so one call clears every rendition. Delete from storage first and purge second, so the CDN cannot fetch the file again. Retry a failed purge and alert after 3 failures. The storage side is Delete files when their owner is deleted. Takedowns arrive through Take notices about illegal content and answer each one.

Examples

JavaScript example

const MAX_PURGE_ATTEMPTS = 3;

export async function removeFileEverywhere(fileId, { deleteObjects, purgeCacheTag, alert }) {
  await deleteObjects(fileId);
  for (let attempt = 1; attempt <= MAX_PURGE_ATTEMPTS; attempt++) {
    if (await purgeCacheTag(`file-${fileId}`)) return true;
  }
  await alert(`CDN purge failed for file ${fileId}`);
  return false;
}

Python example

MAX_PURGE_ATTEMPTS = 3

def remove_file_everywhere(file_id: str, delete_objects, purge_cache_tag, alert) -> bool:
    delete_objects(file_id)
    for _ in range(MAX_PURGE_ATTEMPTS):
        if purge_cache_tag(f"file-{file_id}"):
            return True
    alert(f"CDN purge failed for file {file_id}")
    return False

How to check

Load a public test image and its thumbnail through the CDN, so both are cached. Delete the file. Within 5 minutes both addresses answer 404 or 410 from every CDN region tested, and the job log shows the purge confirmed.

Sources

• GDPR, Regulation (EU) 2016/679, Article 17
• Digital Services Act, Regulation (EU) 2022/2065, Article 6

Related rules

• API-65 Delete files when their owner is deleted in API design
• CMP-63 Take notices about illegal content and answer each one in Compliance and governance
• MED-32 Take files down and restore them after a counter-notice in Files and media