Flask

To run apps built with the Flask web framework using Unit:

1. Install Unit with a Python 3 language module.

2. Create a virtual environment to install Flasks`s PIP package, for instance:

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   $ cd /path/to/app/ # Path to the application directory; use a real path in your configuration $ python --version # Make sure your virtual environment version matches the module version  Python X.Y.Z # Major version, minor version, and revision number $ python -m venv venv # Arbitrary name of the virtual environment $ source venv/bin/activate # Name of the virtual environment from the previous command $ pip install Flask $ deactivate 

   Create your virtual environment with a Python version that matches the language module from Step 1 up to the minor number (X.Y in this example). Also, the app type in Step 5 must resolve to a similarly matching version; Unit doesn’t infer it from the environment.

3. Let’s try a basic version of the quickstart app, saving it as /path/to/app/wsgi.py:

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   from flask import Flask app = Flask(__name__) # Callable name used in Unit's condfiguration  @app.route("/") def hello_world():  return "Hello, World!"

4. Change ownership:

   Run the following command (as root) so Unit can access the application directory (If the application uses several directories, run the command for each one):

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   # chown -R unit:unit /path/to/app/ # User and group that Unit's router runs as by default 

   The unit:unit user-group pair is available only with official packages , Docker images, and some third-party repos. Otherwise, account names may differ; run the ps aux | grep unitd command to be sure.

   For further details, including permissions, see the security checklist.

5. Next, prepare the [ app ] configuration for Unit (use real values for type, home, and path):

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   {  "listeners": {  "*:80": {  "pass": "applications/flask"  }  },  "applications": {  "flask": {  "type": "python 3.Y",  "type_comment": "Must match language module version and virtual environment version",  "path": "/path/to/app/",  "path_comment": "Path to the WSGI module",  "home": "/path/to/app/venv/",  "home_comment": "Path to the virtual environment, if any",  "module": "wsgi",  "module_comment": "WSGI module filename with extension omitted",  "callable": "app",  "callable_comment": "Name of the callable in the module to run"  }  } }

6. Upload the updated configuration.

   Assuming the JSON above was added to config.json. Run the following command as root:

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   # curl -X PUT --data-binary @config.json --unix-socket \  /path/to/control.unit.sock \ # Path to Unit's control socket in your installation  http://localhost/config/ # Path to the config section in Unit's control API 

   The control socket path may vary; run unitd -h or see Startup and shutdown for details.

   After a successful update, your app should be available on the listener’s IP address and port:

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   $ curl http://localhost   Hello, World!