Flask: Flask doens't run when APP is specified with full path

[stillesjo]

Expected Behavior

Previously in our development environment we ran flask app from vscode but after we updated to the latest version of flask we started experiencing problems. After some investigation I found out that in our run configuration we specify the whole path to the app.py-file. Changing to just referencing it directly (i.e. app.py instead of C:\Path\To\Myapp.py) I got it to work.

I recreated the fault in another simpler environment:

The following command runs
env "FLASK_APP=`pwd`/app.py" "FLASK_ENV=Development" "FLASK_DEBUG=1" env/Scripts/python.exe -m flask run

but when you try to access localhost:5000/ you get the following error

```Traceback (most recent call last):
File "C:Users\AlexanderS\code\flask-bugg\env\lib\site-packages\flask\cli.py", line 330, in __call__
rv = self._load_unlocked()
File "C:Users\AlexanderS\code\flask-bugg\env\lib\site-packages\flask\cli.py", line 317, in _load_unlocked
self._app = rv = self.loader()
File "C:Users\AlexanderS\code\flask-bugg\env\lib\site-packages\flask\cli.py", line 372, in load_app
app = locate_app(self, import_name, name)
File "C:Users\AlexanderS\code\flask-bugg\env\lib\site-packages\flask\cli.py", line 246, in locate_app
'Could not import "{name}".'.format(name=module_name)
flask.cli.NoAppException: Could not import "C".

### Actual Behavior
The application should run without errors.

### Environment

* Python version: 3.6.5
* Flask version: 1.0.2
* Werkzeug version: 0.14.1

Recreated the bug with the follow app.py

```python
from flask import Flask

app = Flask(__name__)

@app.route('/')
def hello_world():
    return 'Hello world2'

[garenchan]

It doesn't seem to be supported to import an app through a path with disk driver under Windows.

Flask supports importing app through a combination of module path that does not contain a colon and app variable name, such as 'module_path : my_app'. So if you set FLASK_APP to a path with a colon, the error you described above will be raised.

[ThiefMaster]

Maybe we should use a regex to split this to avoid splitting on :/ and :\?

[stillesjo]

Thanks for the responses. I believe that this is something that never worked but vscode/vscode-python changed how they handle the launch configurations. I believe that perhaps this issue is related

Unless you think that this should be handled I'm OK with closing the issue.

[davidism]

closed by #2963