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62 lines
1.9 KiB
62 lines
1.9 KiB
.. _server: |
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Development Server |
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================== |
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.. currentmodule:: flask |
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Starting with Flask 0.11 there are multiple built-in ways to run a |
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development server. The best one is the :command:`flask` command line utility |
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but you can also continue using the :meth:`Flask.run` method. |
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Command Line |
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------------ |
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The :command:`flask` command line script (:ref:`cli`) is strongly |
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recommended for development because it provides a superior reload |
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experience due to how it loads the application. The basic usage is like |
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this:: |
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$ export FLASK_APP=my_application |
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$ export FLASK_ENV=development |
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$ flask run |
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This enables the development environment, including the interactive |
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debugger and reloader, and then starts the server on |
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*http://localhost:5000/*. |
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The individual features of the server can be controlled by passing more |
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arguments to the ``run`` option. For instance the reloader can be |
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disabled:: |
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$ flask run --no-reload |
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.. note:: |
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Prior to Flask 1.0 the :envvar:`FLASK_ENV` environment variable was |
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not supported and you needed to enable debug mode by exporting |
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``FLASK_DEBUG=1``. This can still be used to control debug mode, but |
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you should prefer setting the development environment as shown |
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above. |
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In Code |
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------- |
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The alternative way to start the application is through the |
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:meth:`Flask.run` method. This will immediately launch a local server |
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exactly the same way the :command:`flask` script does. |
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Example:: |
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if __name__ == '__main__': |
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app.run() |
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This works well for the common case but it does not work well for |
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development which is why from Flask 0.11 onwards the :command:`flask` |
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method is recommended. The reason for this is that due to how the reload |
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mechanism works there are some bizarre side-effects (like executing |
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certain code twice, sometimes crashing without message or dying when a |
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syntax or import error happens). |
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It is however still a perfectly valid method for invoking a non automatic |
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reloading application.
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