How can I change the host and port that the flask command uses?

Question:

I want to change the host and port that my app runs on. I set host and port in app.run, but the flask run command still runs on the default 127.0.0.1:8000. How can I change the host and port that the flask command uses?

if __name__ == '__main__':
    app.run(host='0.0.0.0', port=3000)
set FLASK_APP=onlinegame
set FLASK_DEBUG=true
python -m flask run
Asked By: Marco Cutecchia

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Answers:

The flask command is separate from the flask.run method. It doesn’t see the app or its configuration. To change the host and port, pass them as options to the command.

flask run -h localhost -p 3000

Pass --help for the full list of options.

Setting the SERVER_NAME config will not affect the command either, as the command can’t see the app’s config.


Never expose the dev server to the outside (such as binding to 0.0.0.0). Use a production WSGI server such as uWSGI or Gunicorn.

gunicorn -w 2 -b 0.0.0.0:3000 myapp:app
Answered By: davidism

When you run the application server using the flask run command, the __name__ of the module is not "__main__". So the if block in your code is not executed — hence the server is not getting bound to 0.0.0.0, as you expect.

For using this command, you can bind a custom host using the --host flag.

flask run --host=0.0.0.0

Source

Answered By: TeknasVaruas

You can also use the environment variables FLASK_RUN_PORT and FLASK_RUN_HOST, for instance:

export FLASK_RUN_PORT=8000
export FLASK_RUN_HOST="127.0.0.1"
flask run
 * Running on http://127.0.0.1:8000/

Source: The Flask docs.

Answered By: Akronix
from flask import Flask
app = Flask(__name__)

@app.route("/")
def hello():
    return "Hello World!"

if __name__ == '__main__':
    app.run(host="localhost", port=8000, debug=True)

Configure host and port like this in the script and run it with

python app.py
Answered By: Gokhan Gerdan

You also can use it:

if __name__ == "__main__":
    app.run(host='127.0.0.1', port=5002)

and then in the terminal run this

set FLASK_ENV=development
python app.py
Answered By: StasNemy

You can use this 2 environmental variables:

set FLASK_RUN_HOST=0.0.0.0
set FLASK_RUN_PORT=3000
Answered By: Knemay
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