Merge pull request #2291 from dalf/settings2

[enh] user settings can relied on the default settings

docs/admin/settings.rst

@@ -206,3 +206,80 @@ Engine settings
 
    A few more options are possible, but they are pretty specific to some
    engines, and so won't be described here.
+
+
+.. _settings location:
+
+settings.yml location
+=====================
+
+First, searx will try to load settings.yml from these locations:
+
+1. the full path specified in the ``SEARX_SETTINGS_PATH`` environment variable.
+2. ``/etc/searx/settings.yml``
+
+If these files don't exist (or are empty or can't be read), searx uses the :origin:`searx/settings.yml` file.
+
+.. _ settings use_default_settings:
+
+use_default_settings
+====================
+
+.. note::
+
+   If searx is cloned from a git repository, most probably there is no need to have an user settings.
+
+The user defined settings.yml can relied on the default configuration :origin:`searx/settings.yml` using ``use_default_settings: True``.
+
+In the following example, the actual settings are the default settings defined in :origin:`searx/settings.yml` with the exception of the ``secret_key`` and the ``bind_address``:
+
+.. code-block:: yaml
+
+  use_default_settings: True
+  server:
+      secret_key: "uvys6bRhKHUdFF5CqbJonSDSRN8H0sCBziNSrDGNVdpz7IeZhveVart3yvghoKHA"
+      bind_address: "0.0.0.0"
+
+With ``use_default_settings: True``, each settings can be override in a similar way, the ``engines`` section is merged according to the engine ``name``.
+
+In this example, searx will load all the engine and the arch linux wiki engine has a :ref:`token<private engines>`:
+
+.. code-block:: yaml
+
+  use_default_settings: True
+  server:
+      secret_key: "uvys6bRhKHUdFF5CqbJonSDSRN8H0sCBziNSrDGNVdpz7IeZhveVart3yvghoKHA"
+  engines:
+    - name: arch linux wiki
+      tokens: ['$ecretValue']
+
+It is possible to remove some engines from the default settings. The following example is similar to the above one, but searx doesn't load the the google engine:
+
+.. code-block:: yaml
+
+  use_default_settings:
+      engines:
+         remove:
+           - google
+  server:
+      secret_key: "uvys6bRhKHUdFF5CqbJonSDSRN8H0sCBziNSrDGNVdpz7IeZhveVart3yvghoKHA"
+  engines:
+    - name: arch linux wiki
+      tokens: ['$ecretValue']
+
+As an alternative, it is possible to specify the engines to keep. In the following example, searx has only two engines:
+
+.. code-block:: yaml
+
+  use_default_settings:
+      engines:
+         keep_only:
+           - google
+           - duckduckgo
+  server:
+      secret_key: "uvys6bRhKHUdFF5CqbJonSDSRN8H0sCBziNSrDGNVdpz7IeZhveVart3yvghoKHA"
+  engines:
+    - name: google
+      tokens: ['$ecretValue']
+    - name: duckduckgo
+      tokens: ['$ecretValue']

docs/blog/private-engines.rst

@@ -7,6 +7,8 @@ enabled engines on their instances. It might be because they do not want to
 expose some private information through an offline engine. Or they
 would rather share engines only with their trusted friends or colleagues.
 
+.. _private engines:
+
 Private engines
 ===============