Provide better error messages for invalid environment variables

[jinithin]

It seems like the variable PUSH_NOTIFICATION_REDACT_CONTENT: 'True' does not have any effect on the server when specified in the docker-compose.yml file.

Can this be included, or is there another preferred way to do it?
Would rather not mount the settings-file to the container.

[sirpengi]

It should be:

environment:
  SETTING_PUSH_NOTIFICATION_REDACT_CONTENT: "True"

(that is, you're missing the SETTING_ prefix)

[timabbott]

Yep, that's correct -- we document you need to use the SETTING_ prefix for anything that you want in settings.py.

We should probably figure out a way to do some sort of warning for this type of situation, if it's possible.