There's a related thread for this also --> https://news.ycombinator.com/item?id=27432408

Fastly is down, impacting lot of sites

Strange, I've been getting these for lots of different sites this morning, I wonder if this is a cloudflare issue

Getting multiple 503 errors to different sites.

now, you can access i guess, since fastly is back

Getting a 503 now.

The Varnish error is almost identical to that of the Guardian (newspaper) website in the UK—wondering if they're both using CloudFlare and that it's CloudFlare that is having the issue?

Edit: Perhaps related to this ongoing Fastly outage (https://news.ycombinator.com/item?id=27432408), https://fastly.com returns the same kind of Varnish error and Github currently has no assets being served in their web UI.

Met too