How to configure PIP per config file to use a proxy (with authentification)?

In order to add a proxy option in the terminal the following line solved the problem for me:

pip install package_name_here --proxy https://user_name:password@proxyname:port

Here are the steps how to configure proxy (with auth.) in pip's config file (pip.ini)

1. (if it does not already exist) Create a folder named 'pip' and inside it a file named 'pip.ini' as described here: https://pip.pypa.io/en/stable/user_guide/#config-file (location an name may differ per platform - e.g. on Windows it's %APPDATA%\pip\pip.ini)

2. edit pip.ini file and add

   [global]
   proxy = http://user:password@proxy_name:port
   

3. That's it!

Example for proxy with authentification (user + password):

proxy = http://butch:secret@proxyname:1234

proxyname can be an IP adress, too

Example for proxy without auth.:

proxy = http://proxyname:1234