how to install different python version in docker container
If I look at the Dockerfile here, it installs python3 which by default is installing python 3.5 for debian:stretch. You can instead install python 3.7 by editing the Dockerfile and building it yourself. In your Dockerfile, remove lines 19-25 and replace line 1 with the following, and then build the image locally.
FROM python:3.7-stretchIf you are not familiar with building your own image, download the Dockerfile and keep it in its own standalone directory. Then after cd into the directory, run the command below . You may want to first remove the already downloaded image. After this you should be able to run other docker commands the same way as if you had pulled the image from docker hub.
docker build -t gettyimages/spark .