"Can't find Python executable..." - npm install hangs

Try running this

PYTHON=$PYTHON:/usr/bin/python
export PYTHON

Add this to profile file (like ~/.bash_profile etc. depending on your shell) to make it persistent.

If your python isn't installed in /usr/bin/python then you can run which python to find out where it is installed.

First things first: I want to thank all who pitched in to help me with my issue, and especially @adarsh.

Now the real issue was that I was missing "make" and "gcc". At first, when a compiler message suggested so, I found it absurd. But keep in mind that this is an image PULLed from the Docker registry.

I added "pacman -S --needed --noconfirm make gcc" in my Dockerfile, and the build process completes successfully.

It should go without saying, that I also needed to make the suggested changes to the environmental variables.