Create an operator
==================

Basic functionality
-------------------

Each Yaook operator is built on top of the Operator framework which is responsible for creating the operator state graph, rendering the templates and
managing K8s objects with the K8s API. You can find more details about this process under :doc:`../../explanations/resources_state-graph_operator`.

K8s custom resources are created inside the operators by adding classes inheriting ``sm.ReleaseAwareCustomResource`` [1]_ or ``sm.CustomResource``. These classes contain declarative descriptors as members
which represent Kubernetes object(s) and are managed by Yaook.
There, we can assign jinja templates to the components to dynamically render K8s manifests, and declare dependency relationships between components to ensure they are reconciled in the desired order.

Guide
-----

Here, we will cover in detail how to add a new operator which will serve as a custom controller for new custom resources.
The guide is split into the following parts:

.. toctree::
   :maxdepth: 1

   create_images
   evaluate_requirements
   build_operator


The guide :doc:`./evaluate_requirements` is more targeted towards those who still view the Yaook source code as unknown territory, while the other
guides can always be used by developers and reviewers to ensure all requirements were included during the process.

.. [1] In this guide, ``sm`` always refers to the ``statemachine`` module of Yaook.