docs/apache-airflow/howto/custom-view-plugin.rst

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Customize view of Apache from Airflow web UI
============================================

Airflow has feature that allows to integrate a custom UI along with its
core UI using the Plugin manager

This is an example plugin for Airflow that displays absolutely nothing.

In this plugin, two object references are derived from the base class
``airflow.plugins_manager.AirflowPlugin``. They are flask_blueprints and
appbuilder_views

Using flask_blueprints in Airflow plugin, the core application can be extended
to support the customized application to view Empty Plugin.
In this object reference, the list of Blueprint object with the static template for
rendering the information.

Using appbuilder_views in Airflow plugin, a class that represents a concept is
added and presented with views and methods to implement it.
In this object reference, the list of dictionaries with FlaskAppBuilder BaseView object
and metadata information like name and category is passed on.


Custom view Registration
------------------------

A custom view with object reference to flask_appbuilder and Blueprint from flask
and be registered as a part of a :doc:`plugin </authoring-and-scheduling/plugins>`.

The following is a skeleton for us to implement a new custom view:

.. exampleinclude:: ../empty_plugin/empty_plugin.py
    :language: python


``Plugins`` specified in the ``category`` key of ``appbuilder_views`` dictionary is
the name of the tab in the navigation bar of the Airflow UI. ``Empty Plugin``
is the name of the link under the tab ``Plugins``, which will launch the plugin

We need to add Blueprint for generating the part of the application
that needs to be rendered in Airflow web UI. We can define templates, static files
and this blueprint will be registered as part of the Airflow application when the
plugin gets loaded.

The ``$AIRFLOW_HOME/plugins`` folder with custom view UI have the following folder structure.

::

    plugins
    ├── empty_plugin.py
    ├── templates
    |   └── empty_plugin
    |       ├── index.html
    └── README.md

The HTML files required to render the views built are added as part of the
Airflow plugin into ``$AIRFLOW_HOME/plugins/templates`` folder and defined in the
blueprint.