How can I change the host and port that the flask command uses?
PythonFlaskPython Problem Overview
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
Python Solutions
Solution 1 - Python
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
Solution 2 - Python
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
Solution 3 - Python
You can also use the environment variable FLASK_RUN_PORT
, for instance:
export FLASK_RUN_PORT=8000
flask run
* Running on http://127.0.0.1:8000/
Source: The Flask docs.
Solution 4 - Python
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
Solution 5 - Python
You can use this 2 environmental variables:
set FLASK_RUN_HOST=0.0.0.0
set FLASK_RUN_PORT=3000
Solution 6 - Python
You also can use it:
if __name__ == "__main__":
app.run(host='127.0.0.1', port=5002)
and then in the console use it
set FLASK_ENV=development
python app.py