Restructure documentation

Signed-off-by: Roberto Rosario <roberto.rosario@mayan-edms.com>

docs/chapters/settings.txt

@@ -0,0 +1,126 @@
+========
+Settings
+========
+
+Mayan EDMS can be configure via environment variables or by setting files.
+
+
+.. _environment_variables:
+
+Via environment variables
+=========================
+
+To use environment variables, lookup the name of the setting you want to
+override in the "Settings" menu. The "Settings" menu is located inside the
+"Setup" main menu. To pass a value via an environment variable append
+``"MAYAN_"`` to the name of the settings option. For example, to change
+the number of documents displayed per page (``COMMON_PAGINATE_BY``, by default 40),
+use::
+
+    export MAYAN_COMMON_PAGINATE_BY=10
+
+Restart Mayan EDMS and the new value will take effect. The "Settings" menu
+can be used to verify if the overridden setting value is being interpreted
+correctly.
+
+
+.. _configuration_file:
+
+Via YAML configuration file
+===========================
+
+.. versionadded:: 3.1
+
+It is possible to modify the different settings by creating or editing the
+``media/config.yml`` file. This file is formatted in the YAML markup language
+(http://yaml.org/). Here is an example of what the looks like::
+
+    DOCUMENT_PARSING_AUTO_PARSING: true
+    DOCUMENT_PARSING_PDFTOTEXT_PATH: /usr/bin/pdftotext
+    EMAIL_BACKEND: django.core.mail.backends.smtp.EmailBackend
+    EMAIL_HOST: localhost
+    EMAIL_HOST_PASSWORD: ''
+    EMAIL_HOST_USER: ''
+    EMAIL_PORT: 25
+    EMAIL_TIMEOUT: null
+    EMAIL_USE_SSL: false
+    EMAIL_USE_TLS: false
+    FILE_UPLOAD_MAX_MEMORY_SIZE: 2621440
+    HOME_VIEW: common:home
+
+Every time Mayan EDMS is able to start correctly it will copy the ``config.yml``
+and create a backup copy in the same directory named ``config_backup.yml``.
+This file is used to revert to the last know configuration file known
+to be valid. You can revert manually by copy the file or by using the
+``revertsettings`` management command from the command line.
+
+
+Via Python settings files
+=========================
+
+Another way to configure Mayan EDMS and the one required when more extensive
+setup is required, such as when using external Python libraries, is via
+Python-style, settings files.
+If Mayan EDMS was installed using the Python package a ``mayan_settings``
+folder will created for this purpose. If you installed Mayan EDMS
+according to the :doc:`../chapters/deploying` instructions provided in this
+documentation your ``mayan_settings`` folder should be located in the directory:
+``|MAYAN_MEDIA_ROOT|/mayan_settings/``.
+
+If Mayan EDMS was installed using Docker, the ``mayan_settings`` folder
+will be found inside the install Docker volume. If you installed Mayan EDMS
+according to the :doc:`../chapters/docker/index` instructions provided in this
+documentation your ``mayan_settings`` folder should be located in the directory:
+``/docker-volumes/mayan/mayan_settings``.
+
+Create a file with any valid name and a ``.py`` extension in the
+``mayan_settings`` folder. The file must starts with a global import of
+``mayan.settings.production``. In the form::
+
+    from mayan.settings.production import *
+
+Now add the corresponding lines to override the default settings.
+In the settings file, it is not necessary to prepend the string ``MAYAN_`` to
+the setting option. For example, to change the number of documents displayed
+per page (``COMMON_PAGINATE_BY``, by default 40),
+use::
+
+    COMMON_PAGINATE_BY=10
+
+versus::
+
+    export MAYAN_COMMON_PAGINATE_BY=10
+
+when using the environment variable method.
+
+For this example let's assume the file was saved with the name ``mysettings.py``.
+
+The way used to tell Mayan EDMS to import this file will vary based on the
+installation method.
+
+For the :doc:`../chapters/deploying` method, the full import path will be
+``mayan.media.mayan_settings.mysettings`` and can be passed via the
+``--settings`` command line argument like this::
+
+    |MAYAN_BIN| runserver --settings=mayan.media.mayan_settings.mysettings
+
+or via the ``DJANGO_SETTINGS_MODULE`` environment variable like this::
+
+    export DJANGO_SETTINGS_MODULE=mayan.media.mayan_settings.mysettings
+
+To make the use of the custom Python setting file permanent, update the ``|MAYAN_SUPERVISOR_CONF|``
+file. In the ``[supervisord]`` section, update the ``environment=`` value of
+``DJANGO_SETTINGS_MODULE`` from  the default ``mayan.settings.production`` to
+``mayan.media.mayan_settings.mysettings``. Pay attention to the indentation of
+the ``environment=`` entries.
+
+Force supervisor to read the changes and restart using::
+
+    sudo supervisorctl reread
+    sudo supervisorctl restart all
+
+For the :doc:`../chapters/docker/index` installation method, the full import path will be
+``mayan_settings.mysettings`` and can only be passed via the
+``MAYAN_SETTINGS_MODULE`` environment variable like this::
+
+    docker run <...> -e MAYAN_SETTINGS_MODULE=mayan_settings.mysettings