docker build return error behind proxy

[LucasDM19]

I try to follow the tutorial. I recieved an error on the step 3.
The command build returns an error: The command '/bin/sh -c pip install -r requirements.txt' returned a non-zero code: 1.
I cannot use pip normally behind a proxy. I always had to use the option pip install -–proxy=user:pass@address.
Is it possible to take this factor into account? At least i wanted to customize the build script myself, to get to the end of the tutorial.
I attached the output of the command.
_out.txt