Add restrictions on blobstore consumption

[yamarten]

Is your feature request related to a problem? Please describe.

Currently, there is an individual blob size limit (PDS_BLOB_UPLOAD_LIMIT) in the PDS implementation here, but the total is unlimited. Therefore, there is a concern that a small number of accounts will over-consume storage.

Describe the solution you'd like

Set an upper limit on the total blob size that can be uploaded within a certain period of time. This will allow PDS administrators to control their costs.

Describe alternatives you've considered

The rate limit of uploadBlob already exists. However, this does not directly reflect the PDS cost because the individual blob sizes vary.

You can also consider a way to simply limit the total amount of data without window. In this case, please note that if the PDS does not count at least GC or deletion, it is very disadvantageous for long-term users.

Additional context

There are several movements that accelerate the blobstore consumption.

• Increase the upper limit of individual blob size to support Bluesky videos
• A new tool called ATFile that uses PDS as file storage
• Video streaming experiment using blob by GrayHaze
• Reasing interest in image posting services

[Invertex]

Definitely an important thing to consider if the BSKY team want to keep the site lean so that it doesn't require as much income generation (which almost always is going to be detrimental to user experience and integrity). And it would also aid in combating the bots that post a constant stream of content.

And in that same sense, increased upload limits would be another useful way to drive subscriptions in a way that isn't bad for the platform. I know they already talked about having higher quality video be one of those features too.

---

I think on this subject, I would also recommend there to be some sort of "limit rollover". Where, if you are exceeding your upload limit, you can still upload more, but it will be subtracted from the next period's usage allowance (so still being limited to 2x the usage limit). And will give a strong warning about this extra usage.
I say this just to avoid situations of someone being in an emergency situation where they might need to upload something in that moment and being at their limit already and not being able to. Or just for important business-sake too.

And the time periods can't be too long (like a year) otherwise that still enables a lot of upload in a short period of time, and the longer the time period, the larger the burden you put on the users to segment their usage over a whole year, versus only having to worry about something like a 2-4 week period.