Flask at first run Do not use the development server in a production environment

Question

I installed the Flask plugin in PyCharm Community Edition and I just have this simple code in my flask app   from flask import Flask app   Flask   name      app route      def index        return   lt h1 gt Hello  lt  h1 gt    if   name         main         app run debug True    And I get this message   WARNING  This is a development server  Do not use it in a production deployment  Use a production WSGI server instead    Restarting with stat   Debugger is active    Debugger PIN  123-456-789   Running on http   127 0 0 1 5000    Why am I getting this error when I run Flask     A previous version of the message read  Do not use the development server in a production environment

User · Answer

When running the python file  you would normally do this  python app py   This will display these messages   To avoid these messsages  Inside the CLI  Command Line Interface   run these commands   export FLASK APP app py export FLASK RUN HOST 127 0 0 1 export FLASK ENV development export FLASK DEBUG 0 flask run   This should work perfectlly

User · Answer

Unless you tell the development server that it s running in development mode  it will assume you re using it in production and warn you not to  The development server is not intended for use in production  It is not designed to be particularly efficient  stable  or secure  Enable development mode by setting the FLASK ENV environment variable to development    export FLASK APP example   export FLASK ENV development   flask run  If you re running in PyCharm  or probably any other IDE  you can set environment variables in the run configuration  Development mode enables the debugger and reloader by default  If you don t want these  pass --no-debugger or --no-reloader to the run command   That warning is just a warning though  it s not an error preventing your app from running  If your app isn t working  there s something else wrong with your code

User · Answer

The official tutorial discusses deploying an app to production  One option is to use Waitress  a production WSGI server  Other servers include Gunicorn and uWSGI      When running publicly rather than in development  you should not use   the built-in development server  flask run   The development server   is provided by Werkzeug for convenience  but is not designed to be   particularly efficient  stable  or secure       Instead  use a production WSGI server  For example  to use Waitress    first install it in the virtual environment         pip install waitress       You need to tell Waitress about your application  but it doesn   t use   FLASK APP like flask run does  You need to tell it to import and call   the application factory to get an application object         waitress-serve --call  flaskr create app  Serving on http   0 0 0 0 8080    Or you can use waitress serve   in the code instead of using the CLI command   from flask import Flask  app   Flask   name      app route      def index        return   lt h1 gt Hello  lt  h1 gt    if   name         main         from waitress import serve     serve app  host  0 0 0 0   port 8080      python hello py

User · Answer

If for some people  like me earlier  the above answers don t work  I think the following answer would work  for Mac users I think  Enter the following commands to do flask run    export FLASK APP   hello py   export FLASK ENV   development   flask run   Alternatively you can do the following  I haven t tried this but one resource online talks about it     export FLASK APP   hello py   python -m flask run   source  For more

[python] Flask at first run: Do not use the development server in a production environment

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