Increase length of contrib.sites domain field

[thenewguy]

The domain value is currently limited to 100 characters. This seems like an arbitrary limit. Apps served via cloud providers like AWS can approach this limit pretty easily when accessed via their public path -> for example I just checked a few apps available through AWS load balancers and their FQDN was around 90 characters.

It isn't unfeasible for deeply nested domains to hit this limit either. Since many apps rely on the site record, these sites are dangerously close to not working with Django.

It would be helpful here to increase the size to the max portable length of a charfield at 255 characters.

[Carlton Gibson]

Hi.

I'm not entirely convinced here.

• Seems like even the most horrible names leave some headroom by your report. Is it even necessary?
• Surely most folks use DNS? What's the % of folks using such names as site records? Not sure we need to impose a change on everyone for that. A migration isn't zero cost.
• Why 255? That seems a LOT of extra headroom, given that we're not hitting the limit already, and in other cases we favored "human values" over values such as 255. (These days, is 255 even the right "machine value" for the supported DBs?)

It's the kind of change that needs consensus on the DevelopersMailingList.