Read config vars from files

[janost]

Fixes #1194.

This is a better implementation of the change previously posted in #1235.

This change allows the user to read configuration variable values from arbitrary files by using the _FILE suffix in environment variables.

[dani-garcia]

Looks good to me, I also mostly agree with @BlackDex said here: #1235 (comment).

Reloading is a nice feature but the main problem is there are some settings that aren't reloadable on the fly, and until rocket async we don't have a way to restart the server itself, so it will mean it will work for some settings and not others.

If a user is loading the config from a file, it probably won't make much sense to let them set the value in the admin page config, because they probably want to control where and how the value is stored. At the same time, that's something they can themselves look for and be careful around it.

Also, maybe in this case we should completely disable the option to see the secrets from the admin page?

We should consider what we are going to do about that before the next release, or at least leave it as an undocumented feature until we have all those corners fleshed out.

Thanks!

[ahmaddxb]

I tried doing this but it didn't work

    environment:
       - ADMIN_TOKEN_FILE=/run/secrets/vaultwarden_admin_token

[BlackDex]

@ahmaddxb , if you ever used the /admin interface to save settings, those env/file items are being overwritten.

[ahmaddxb]

I got it work i was missing this,

    secrets:
      - vaultwarden_admin_token