Looks like it's a DDOS attack. I'm guessing the attackers figured out that there's a lot processing is required to generate a repo download (and thus using it as a L7 attack).

I'm surprised that the downloads aren't cached. Maybe the attackers are using cache busting or similar to bypass it.

Seems to be back up now.

We’ve just come back up and we’re monitoring.

Does indeed seem to work again, good stuff! (9/10 times, still some sporadic 'whoops' pages).

Why makes you saw it's a DDoS attack?

Can confirm that it's back up now.

The status page shows a few events related to downloads; generating a repo download is apparently ripe for an L7 DoS attack.

Probably unrelated, but their status page shows Docker Web to be having issues as well, same on Docker's own status page, but it is up for me.

https://status.docker.com