[x] Create requirements.txt with flask framework dependency
[x] Create Dockerfile using alpine image: https://docs.docker.com/compose/gettingstarted/ there's quite a good Dockerfile in here. Try to read about every command Dockerfile is using in here in the docker manual. Use python:3-alpine image instead, that's more usual one, latest python3 version will be used.
python:3-alpine
image instead, that's more usual one, latest python3 version will be used.