Add possibility to use environment variables

[junpet]

You can use environment variables instead of storing passwords in
config.py as plaintext. Note that settings.py is still needed, because
this file reads the environment variables.

Changes in settings.py:

• Only the domain has to be specified for the URLs. Previously you used
  'https://example.com/ocs/v2.php/apps/notifications/api/v2/notifications'
  now you only specify 'https://example.com'. This is valid for both
  Nextcloud and Gotify URL as well.

Some minimal adjustments in push_msg.py:

• Remove unused json import
• Use single quote globally
• Remove unnecessary whitespace character
• Break some long lines

[mrchainman]

Hi @junpet
thanks for your work.
Can you confirm, that using environment variables works also with special characters in passwords, i.e. quotes etc.?

EDIT:
I just tried running it, but the environment variables are not being read. Which shell did you use?

[junpet]

Hi @mrchainman!

Sorry for late answer. I used VSCode on Windows with Python 3 dev container. It looks like this container uses bash. I've created environment variables with the following command:

export NEXTCLOUD_URL="https://cloud.mydomain.com"

I think you can use special characters in the password. IIRC you need to escape $ character, and you can't use = and NUL, but I haven't tested. See more.

BTW, I've created a docker branch as well and I run this script in a container for some time, working like a charm.

[mrchainman]

@junpet alright, i will retest it and report back.

[mrchainman]

@junpet Sorry, still didn't geht around testing, have a lot going on right now... Would you be interested in maintaining this project?

[junpet]

@mrchainman Unfortunately I have not much time either, so it wouldn't be much difference if I would maintain this project. Just keep it. Don't worry about merging this. You'll do it if you have time. :) Have a nice day. :)