Server command ignores some values in config associated with app

[dlipovetsky]

Running the below code with Flask 0.10.1 and Flask-Script 2.0.5 will result in a server starting at port 5000, though the app is explicitly configured to use port 8888. To the end user, the SERVER_NAME configuration value appears to be ignored.

from flask import Flask
from flask.ext.script import Manager

app = Flask(__name__)
app.config['SERVER_NAME'] = 8888
manager = Manager(app)

if __name__ == '__main__':
    manager.run()

As of 0.10, Flask parses SERVER_NAME to set the host and port, falling to defaults if not set. (https://github.com/mitsuhiko/flask/blob/master/flask/app.py#L823)

Server command sets its own defaults (https://github.com/smurfix/flask-script/blob/master/flask_script/commands.py#L339) and initializes app with them (https://github.com/smurfix/flask-script/blob/master/flask_script/commands.py#L417), so the end result is an app that has all configuration settings, but some are not applied.

I'm not sure if this behavior merits changing. However, I think it should be documented, since it is confuses the end user when certain configuration values (e.g. SERVER_NAME) appear to be ignored.

[nfvs]

This seems to have been fixed at some point, although Flask requires SERVER_NAME to be a string, setting it to an int throws an exception in Flask, setting it without a host makes it be ignored.

[tdeck]

I am just starting with Flask-Script and am experiencing the same issue. It looks like runserver calls app.run like this:

        app.run(host=host,
                port=port,
                debug=use_debugger,
                use_debugger=use_debugger,
                use_reloader=use_reloader,
                threaded=threaded,
                processes=processes,
                passthrough_errors=passthrough_errors,
                **self.server_options)

with default values for host, port, etc... This overrides all the normal flask configuration environment variables, which is pretty frustrating to work around.

[tdeck]

In case anyone else lands on this, I've found a workaround that works in the specific case of SERVER_NAME, which is simply to make my own runserver command that goes back to providing Nones for host= and port= like so:

...
manager = Manager(app)
manager.add_command(
    "runserver",
    flask_script.commands.Server(host=None, port=None)
)

This will cause Flask to use whatever fallback it chooses, which will be the environment, then Flask's own internal defaults.

[ariscn]

+1, just bit by this.

Thanks for the workaround, @tdeck!