Yesod scaffold port variable incompatible with Keter

[SongWithoutWords]

The Yesod scaffold port environment variable is YESOD_PORT:

yesod-scaffold/config/settings.yml

Line 6 in ce163c0

port: "_env:YESOD_PORT:3000" # NB: The port `yesod devel` uses is distinct from this value. Set the `yesod devel` port from the command line.

This is incompatible with the environment variable used by Keter which is PORT. The results of this discrepancy is a silent failure when deploying apps created from the Yesod scaffold with Keter, as described here: snoyberg/keter#189.

The documentation for Keter has since been updated to warn of this discrepancy, but it would be ideal if the Yesod scaffold worked with Keter out of the box.

[psibi]

The prefixing of YESOD was done recently. See this thread to learn more about the reasoning: yesodweb/yesod#1517 (comment)

Probably keter should be updated to make it work with the new environment variable ? A fix there would be ideal, IMO.

[SongWithoutWords]

Wouldn't changing the variable on Keter's end run the risk of breaking existing server apps?