Flask cli can't import application set with FLASK_APP

Question

Following the Flask 0.11 documentation, I cloned the Flask repo, created a virtualenv, and installed Flask via pip install flask. I went into the examples/flaskr directory, set the FLASK_APP environment variable, then executed:

flask run

However, I got the following error:

Traceback (most recent call last):
  File "c:\python34\Lib\runpy.py", line 170, in _run_module_as_main
    "__main__", mod_spec)
  File "c:\python34\Lib\runpy.py", line 85, in _run_code
    exec(code, run_globals)
  File "D:\GitHub\flask\venv\Scripts\flask.exe\__main__.py", line 9, in <module>
  File "d:\github\flask\venv\lib\site-packages\flask\cli.py", line 478, in main
    cli.main(args=args, prog_name=name)
  File "d:\github\flask\venv\lib\site-packages\flask\cli.py", line 345, in main
    return AppGroup.main(self, *args, **kwargs)
  File "d:\github\flask\venv\lib\site-packages\click\core.py", line 696, in main
    rv = self.invoke(ctx)
  File "d:\github\flask\venv\lib\site-packages\click\core.py", line 1055, in invoke
    cmd_name, cmd, args = self.resolve_command(ctx, args)
  File "d:\github\flask\venv\lib\site-packages\click\core.py", line 1094, in resolve_command
    cmd = self.get_command(ctx, cmd_name)
  File "d:\github\flask\venv\lib\site-packages\flask\cli.py", line 316, in get_command
    rv = info.load_app().cli.get_command(ctx, name)
  File "d:\github\flask\venv\lib\site-packages\flask\cli.py", line 209, in load_app
    rv = locate_app(self.app_import_path)
  File "d:\github\flask\venv\lib\site-packages\flask\cli.py", line 89, in locate_app
    __import__(module)
ImportError: No module named 'flaskr'

How do I correctly run the flaskr example?

Answer 1

I was setting FLASK_APP=flaskr. Since I hadn't installed my app as a package in my virtualenv, I needed to add the .py extension.

export FLASK_APP=flaskr.py