Handle environment variables better

[almet]

@zorun said in another discussion :

I think variables are getting out of control: we already had 4 places where we define them, and that's now 5!

[almet]

I think we should find a better way to handle this. We currently have these places where we define variables :

• In the default_settings.py
• In the entrypoint.sh file
• In the ihatemoney.cfg.j2 template file
• In the Dockerfile
• In the docs

Yeah. I think we could do a better job here :-D

[zorun]

I just found out we have another place with variables: https://hub.docker.com/r/ihatemoney/ihatemoney

It doesn't seem to come from our repo, and it's outdated (the format of MAIL_DEFAULT_SENDER has changed to be a single string)

[almet]

We would like to have a unique place where all variables are defined, in a formal way: name, type, doc, default value. We would include settings from ihatemoney and Flask ones, SQLAlchemy, etc.

Then, we would use this unique source of configuration variables to generate the rest. For docker, we could replace the shell entrypoint with a python entrypoint to ease the process.