SERVER_NAME and url_for() - why should we use url_for() ?

[flipmcf]

flask's SERVER_NAME setting is bothersome.

I stopped using url_for() - maybe for good?

In a load-balancing and CDN situation where the instance is a different hostname or responding to a different hostname than the actual published URL, setting SERVER_NAME to the CDN hostname might break routing - flask replies with 404 on every endpoint route because the SERVER_NAME doesn't match the host header it gets from 'upstream'.

But not setting SERVER_NAME makes flask guess about the protocol scheme and hostname and you might get some weird host in your m3u8 that points to a local instance that is not publically accessable. like http://172.31.21.141/i/path/to/file.mp4/index_0_av.m3u8 and the streams fail to play.

so, look carefully at casterpak.py 'get_base_url' and decide what's best. right now we don't tell flask what the server name is and manually construct the base url without using 'url_for()' and maybe that's ok. I don't know.

[flipmcf]

12c9e71 is where this mess begins.