Run Flask using python3 not python

Question

How can you run Flask app which uses a specific version of python?

On my env \"python\" = python2.7 and \"python3\" = python3.6. I have installed Flask using pip3. I

Answer 1

There are several ways:

1. Virtualenv lets you create isolated python environments with different versions (this is the way I would recommend)

2. You can put #!/usr/bin/python3 on top of your python file (see here)

3. Or you can start your script with python3 script.py

4. As mentioned in the comments above you can also start your script inside a Docker container that hosts a python3 installation

Answer 2

What I did was:

1. which flask, to find flask binary executable path (in my case /home/myuser/.local/bin/flask

2. edit /home/myuser/.local/bin/flask, changing the first line from #!/usr/bin/python to #!/usr/bin/python3

In summary, making flask use python3, regardless of which shebang was specified in other scripts, since those scripts are not the entrypoint of execution, but flask is. I didn't have to change the shebang in any of my scripts, just the flask executable.