> Using our public instance is completely free: there are no limits on the number of map views or requests. There’s no registration, no user database, no API keys, and no cookies. We aim to cover the running costs of our public instance through donations.
> Is commercial usage allowed?
> Yes.
IMHO, reading this and then just using it, makes a lot of sense. Yeah, you could put a cache infront of their CDN, but why, when they said it's all good, no limits, for free?
I might wonder a bit, if I knew the bandwidth it was using, but I might be busy with other stuff if my site went unexpectedly viral.
Seriously, whose first thought on reading that is “oh great, I can exploit this”.
But it depends on the project architecture. If the tiles are needed only client-side, then there's really little reason to cache things on _my_ server. That would imply I'm better at caching openstreetmap tiles than... openstreetmap. Plus you're just making the system needlessly more complicated.
And there's little reason for openstreet map to be upset, since it's not like _I_ am making 2 million requests - there are 2 million separate users of osm+. It's aligned to their incentive of having more people use osm and derived works. All is well.
Presumably a caching server would be 10GbE, 40GbE, or 100GbE
56Gbit/sec of pre-generated data is definitely something that you can handle from 1 or 2 decent servers, assuming each request doesn't generate a huge number of random disk reads or something
You are not talking about an insane amount of data if it's 56 Gbit/s. Of course a caching server could handle that.
Source: Has written servers that saturated 40gig (with TLS) on an old quadcore.
If you need to go to disk to serve large parts of it, it's a different beast. But then again, Netflix was doing 800gig already three years ago (in large part from disk) and they are handicapping themselves by choosing an OS where they need to do significant amounts of the scaling work themselves.
What I've been referring to is the fact that even unlimited 1 Gbps connections can be quite expensive, now try to find a 2x40 gig connection for a reasonable money. That one user generated 200 TB in 24 hours! I have no idea about bandwidth pricing, but I bet it ain't cheap to serve that.