.. _engines-dev:

=============== Engine Overview

.. contents:: :depth: 3 :local: :backlinks: entry

.. _metasearch-engine: https://en.wikipedia.org/wiki/Metasearch_engine

.. sidebar:: Further reading ..

:ref:configured engines
:ref:settings engines

SearXNG is a metasearch-engine_, so it uses different search engines to provide better results.

Because there is no general search API which could be used for every search engine, an adapter has to be built between SearXNG and the external search engines. Adapters are stored under the folder :origin:searx/engines.

.. _general engine configuration:

General Engine Configuration

It is required to tell SearXNG the type of results the engine provides. The arguments can be set in the engine file or in the settings file (normally settings.yml). The arguments in the settings file override the ones in the engine file.

It does not matter if an option is stored in the engine file or in the settings. However, the standard way is the following:

.. _engine file:

Engine File

.. table:: Common options in the engine module :width: 100%

======================= =========== ======================================================== argument type information ======================= =========== ======================================================== categories list categories, in which the engine is working paging boolean support multiple pages time_range_support boolean support search time range engine_type str - online :ref:[ref] <online engines> by default, other possibles values are: - offline :ref:[ref] <offline engines> - online_dictionary :ref:[ref] <online dictionary> - online_currency :ref:[ref] <online currency> - online_url_search :ref:[ref] <online url search> ======================= =========== ========================================================

.. _engine settings:

Engine `settings.yml`

For a more detailed description, see :ref:settings engines in the :ref:settings.yml.

.. table:: Common options in the engine setup (settings.yml) :width: 100%

======================= =========== ================================================== argument type information ======================= =========== ================================================== name string name of search-engine engine string name of searxng-engine (file name without .py) enable_http bool enable HTTP (by default only HTTPS is enabled). shortcut string shortcut of search-engine timeout string specific timeout for search-engine display_error_messages boolean display error messages on the web UI proxies dict set proxies for a specific engine (e.g. proxies : {http: socks5://proxy:port, https: socks5://proxy:port}) ======================= =========== ==================================================

.. _engine overrides:

Overrides

A few of the options have default values in the namespace of the engine's python module, but are often overwritten by the settings. If None is assigned to an option in the engine file, it has to be redefined in the settings, otherwise SearXNG will not start with that engine (global names with a leading underline can be None).

Here is an very simple example of the global names in the namespace of engine's module:

.. code:: python

engine dependent config

categories = ['general'] paging = True _non_overwritten_global = 'foo'

.. table:: The naming of overrides is arbitrary / recommended overrides are: :width: 100%

======================= =========== =========================================== argument type information ======================= =========== =========================================== base_url string base-url, can be overwritten to use same engine on other URL number_of_results int maximum number of results per request language string ISO code of language and country like en_US api_key string api-key if required by engine ======================= =========== ===========================================

.. _engine request:

Making a Request

To perform a search an URL have to be specified. In addition to specifying an URL, arguments can be passed to the query.

.. _engine request arguments:

Passed Arguments (request)

These arguments can be used to construct the search query. Furthermore, parameters with default value can be redefined for special purposes.

.. _engine request online:

.. table:: If the engine_type is :py:obj:online <searx.search.processors.online.OnlineProcessor.get_params> :width: 100%

====================== ============== ======================================================================== argument type default-value, information ====================== ============== ======================================================================== url str '' method str 'GET' headers dict {} data dict {} cookies dict {} verify bool True headers.User-Agent str a random User-Agent category str current category, like 'general' safesearch int 0, between 0 and 2 (normal, moderate, strict) time_range Optional[str] None, can be day, week, month, year pageno int current pagenumber searxng_locale str SearXNG's locale selected by user. Specific language code like 'en', 'en-US', or 'all' if unspecified. ====================== ============== ========================================================================

.. _engine request online_dictionary:

.. table:: If the engine_type is :py:obj:online_dictionary <searx.search.processors.online_dictionary.OnlineDictionaryProcessor.get_params>, in addition to the :ref:online <engine request online> arguments: :width: 100%

.. _engine request online_currency:

.. table:: If the engine_type is :py:obj:online_currency <searx.search.processors.online_currency.OnlineCurrencyProcessor.get_params>, in addition to the :ref:online <engine request online> arguments: :width: 100%

.. _engine request online_url_search:

.. table:: If the engine_type is :py:obj:online_url_search <searx.search.processors.online_url_search.OnlineUrlSearchProcessor.get_params>, in addition to the :ref:online <engine request online> arguments: :width: 100%

                                     .. code:: python

                                        {
                                          'http': str,
                                          'ftp': str,
                                          'data:image': str
                                        }

====================== ============== ========================================================================

Specify Request

The function :py:func:def request(query, params): <searx.engines.demo_online.request> always returns the params variable, the following parameters can be used to specify a search request:

.. table:: :width: 100%

=================== =========== ========================================================================== argument type information =================== =========== ========================================================================== url str requested url method str HTTP request method headers dict HTTP header information data dict HTTP data information cookies dict HTTP cookies verify bool Performing SSL-Validity check allow_redirects bool Follow redirects max_redirects int maximum redirects, hard limit soft_max_redirects int maximum redirects, soft limit. Record an error but don't stop the engine raise_for_httperror bool True by default: raise an exception if the HTTP code of response is >= 300 =================== =========== ==========================================================================

Making a Response

In the response function of the engine, the HTTP response (resp) is parsed and a list of results is returned.

A engine can append result-items of different media-types and different result-types to the result list. The list of the result items is render to HTML by templates. For more details read section:

:ref:simple theme templates
:ref:result types

Engine Overview