--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/doc/apps.rst	Fri May 31 11:08:18 2024 +0200
@@ -0,0 +1,196 @@
+.. _libervia-app-config:
+
+=================================
+Libervia App Configuration (YAML)
+=================================
+
+The Libervia application uses a YAML configuration file to define various aspects of the
+application's behavior, environment, and settings.
+
+The file will be parsed by `PyYAML`_ which is a full-featured YAML implementation. Check
+its documentation for details.
+
+Below is the documentation explaining the structure and functionality of each field in the
+YAML file.
+
+=================
+Root-Level Fields
+=================
+
+- ``type``: Specifies the type of the application. See :ref:`libervia-app_type`.
+
+- ``prepare``: Information required to prepare the environment. See :ref:`libervia-app_prepare`.
+
+- ``files``: Specifies files to be created with defined content. See :ref:`libervia-app_files`.
+
+- ``override``: Allows to override or add to default configurations. See :ref:`libervia-app_override`.
+
+- ``expose``: Specifies configurations exposed to frontends or administrators. See :ref:`libervia-app_expose`.
+
+==================
+Detailed Sections
+===================
+
+.. _libervia-app_type:
+
+type
+^^^^
+
+Currently, the only supported type is ``docker-compose``.
+
+.. _libervia-app_prepare:
+
+prepare
+^^^^^^^
+
+The ``prepare`` section specifies things like git repositories to be cloned before running the application.
+
+Example
+-------
+Cloning the repository at `https://example.org/some/repository.git` to prepare the app:
+
+.. code-block:: yaml
+
+  prepare:
+    git: https://example.org/some/repository.git
+
+.. _libervia-app_files:
+
+files
+^^^^^
+
+The ``files`` section specifies additional files to be created for the application.
+
+The YAML key is the name of the file to be created, and the content specified will
+populate that file.
+
+Example
+-------
+Creating a file named `settings-override.py` with the content `USE_X_FORWARDED_HOST = True`:
+
+.. code-block:: yaml
+
+  files:
+    settings-override.py:
+      content: |
+        USE_X_FORWARDED_HOST = True
+
+.. _libervia-app_override:
+
+override
+^^^^^^^^
+
+The ``override`` section allows for the specification or override of configurations. This
+creates a ``docker-compose.override.yml`` file that will be merged with the default
+``docker-compose.yml``. For more information, see `Docker documentation
+<https://docs.docker.com/compose/reference/#specifying-multiple-compose-files>`_.
+
+Example
+-------
+Overriding the `ports` for the `example_app` service to expose port `8080`:
+
+.. code-block:: yaml
+
+  override:
+    services:
+      example_app:
+        ports:
+          - "8080"
+
+.. _libervia-app_expose:
+
+Exposing Data
+^^^^^^^^^^^^^
+
+The `expose` section specifies the configurations that are exposed to users or frontends.
+See :ref:`libervia-app_param` for a reference of some exposed data. Ports and generated
+passwords are exposed in dicts, respectively at the ``ports`` and  ``passwords`` key.
+
+.. _libervia-app_yaml-tags:
+
+YAML Tags
+^^^^^^^^^
+
+The following YAML tags can be used in the Libervia App configuration file:
+
+.. _libervia-app_conf:
+
+!libervia_conf
+++++++++++++++
+
+Get a value from Libervia configuration. A list is expected with either:
+
+- `name` of a config parameter
+- `section` and `name` of a config parameter
+- `section`, `name`, and `default` value of a config parameter
+- `section`, `name`, `default` value, and `filter` (either `first` or `not`)
+
+Filter options:
+
+- `first`: get the first item of the value
+- `not`: get the opposite value (to be used with booleans)
+
+Example
+-------
+Getting a value from Libervia configuration:
+
+.. code-block:: yaml
+
+  !libervia_conf [section, name, default]
+
+.. _libervia-app_generate_pwd:
+
+!libervia_generate_pwd
++++++++++++++++++++++
+
+Generate a password and store it in persistent data. If the password has already been generated previously, it is reused.
+
+Arguments:
+
+- `name` (str) **required**: Name of the password. Will be used to store it so it kept
+  between restarts.
+- `size` (int): Size of the password to generate. Default to 30
+
+Example
+-------
+Generating a password named ``some_password`` with a size of 32 characters:
+
+.. code-block:: yaml
+
+  !libervia_generate_pwd {name: some_password, size: 32}
+
+.. _libervia-app_param:
+
+!libervia_param
+++++++++++++++
+
+Get a parameter specified when starting the application. The value can be either the name
+of the parameter to get, or a list as `[name, default_value]`.
+
+
+
+Available parameters:
+
+url_prefix
+    The internal URL where the app will be served.
+web_label
+    Label which will be used in Web frontend.
+web_url_path
+    Public facing URL path which will be used in the web frontend to access the app.
+web_external
+    If True, the web frontend will open the app in a separated page instead of embedding
+    it.
+front_url
+    Whole URL to access the app. It is specified when the app has its own domain or
+    subdomain.
+
+Example
+-------
+Getting a parameter:
+
+.. code-block:: yaml
+
+  !libervia_param [url_prefix, /some_app]
+
+.. _PyYAML: https://pyyaml.org/
+