The S3 API doesn't have the concurrency control primitives necessary to guarantee consistency in the face of concurrent writes.
I wrote a distributed lock on Google Cloud Storage. https://www.joyfulbikeshedding.com/blog/2021-05-19-robust-di...
During my research it was quickly evident that GCS has more concurrency control primitives than S3. Heck S3 didn't even guarantee strong read-after-write until recently.
While I'm sure you're right, this VFS implementation doesn't use any of that stuff. They just handwave concurrent writes away by saying the application has to ensure a single writer on its own. An S3 implementation appears to be planned; it's mentioned in the comments in the bcvmodule.c file.
Ah, I'm guessing that's the same reason why many "cloud storage as a backend" stuff (e.g. Terraform/Vault storage backends, Delta.io backends) require DynamodDB + S3
I thought it was a sign of who paid for the feature. I have no insight as to whether or not this is true, but leaving out S3 made me assume either Google or Microsoft (or a third party heavily tied to one of these clouds) paid for this to be added.
> The system currently supports Azure Blob Storage and Google Cloud Storage.
I'd interpret that as either a hard "fuck you" to AWS, or a sign that the S3 API is somehow more difficult to use for this purpose.