Merge pull request #4467 from safwanrahman/search_docs

[Fix #4268] Adding Documentation for upgraded Search

Author: ericholscher

docs/custom_installs/elasticsearch.rst

@@ -0,0 +1,110 @@
+Search
+============
+
+Read The Docs uses Elasticsearch_ instead of the built in Sphinx search for providing better search
+results. Documents are indexed in the Elasticsearch index and the search is made through the API.
+All the Search Code is open source and lives in the `Github Repository`_.
+Currently we are using the `Elasticsearch 6.3`_ version.
+
+Local Development Configuration
+-------------------------------
+
+Installing and running Elasticsearch
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+You need to install and run Elasticsearch_ version 6.3 on your local development machine.
+You can get the installation instructions
+`here <https://www.elastic.co/guide/en/elasticsearch/reference/6.3/install-elasticsearch.html>`_.
+Otherwise, you can also start an Elasticsearch Docker container by running the following command::
+
+    docker run -p 9200:9200 -p 9300:9300 \
+           -e "discovery.type=single-node" \
+           docker.elastic.co/elasticsearch/elasticsearch:6.3.2
+
+Indexing into Elasticsearch
+^^^^^^^^^^^^^^^^^^^^^^^^^^^
+For using search, you need to index data to the Elasticsearch Index. Run `reindex_elasticsearch`
+management command::
+
+    ./manage.py reindex_elasticsearch
+
+For performance optimization, we implemented our own version of management command rather than
+the built in management command provided by the `django-elasticsearch-dsl`_ package.
+
+Auto Indexing
+^^^^^^^^^^^^^
+By default, Auto Indexing is turned off in development mode. To turn it on, change the
+`ELASTICSEARCH_DSL_AUTOSYNC` settings to `True` in the `readthedocs/settings/dev.py` file.
+After that, whenever a documentation successfully builds, or project gets added,
+the search index will update automatically.
+
+
+Architecture
+------------
+The search architecture is devided into 2 parts.
+One part is responsible for **indexing** the documents and projects and
+the other part is responsible for querying the Index to show the proper results to users.
+We use the `django-elasticsearch-dsl`_ package mostly to the keep the search working.
+`django-elasticsearch-dsl`_ is a wrapper around `elasticsearch-dsl`_ for easy configuration
+with Django.
+
+Indexing
+^^^^^^^^
+All the Sphinx documents are indexed into Elasticsearch after the build is successful.
+Currently, we do not index MkDocs documents to elasticsearch, but
+`any kind of help is welcome <https://github.com/rtfd/readthedocs.org/issues/1088>`_.
+
+How we index documentations
+~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+After any build is successfully finished, `HTMLFile` objects are created for each of the
+`HTML` files and the old version's `HTMLFile` object is deleted. By default,
+`django-elasticsearch-dsl`_ package listens to the `post_create`/`post_delete` signals
+to index/delete documents, but it has performance drawbacks as it send HTTP request whenever
+any `HTMLFile` objects is created or deleted. To optimize the performance, `bulk_post_create`
+and `bulk_post_delete` Signals_ are dispatched with list of `HTMLFIle` objects so its possible
+to bulk index documents in elasticsearch ( `bulk_post_create` signal is dispatched for created
+and `bulk_post_delete` is dispatched for deleted objects). Both of the signals are dispatched
+with the list of the instances of `HTMLFile` in `instance_list` parameter.
+
+We listen to the `bulk_post_create` and `bulk_post_delete` signals in our `Search` application
+and index/delete the documentation content from the `HTMLFile` instances.
+
+
+How we index projects
+~~~~~~~~~~~~~~~~~~~~~
+We also index project information in our search index so that the user can search for projects
+from the main site. `django-elasticsearch-dsl`_ listen `post_create` and `post_delete` signals of
+`Project` model and index/delete into Elasticsearch accordingly.
+
+
+Elasticsearch Document
+~~~~~~~~~~~~~~~~~~~~~~
+
+`elasticsearch-dsl`_ provides model-like wrapper for the `Elasticsearch document`_.
+As per requirements of `django-elasticsearch-dsl`_, it is stored in the
+`readthedocs/search/documents.py` file.
+
+    **ProjectDocument:** It is used for indexing projects. Signal listener of
+    `django-elasticsearch-dsl`_ listens to the `post_save` signal of `Project` model and
+    then index/delete into Elasticsearch.
+
+    **PageDocument**: It is used for indexing documentation of projects. By default, the auto
+    indexing is turned off by `ignore_signals = settings.ES_PAGE_IGNORE_SIGNALS`.
+    `settings.ES_PAGE_IGNORE_SIGNALS` is `False` both in development and production.
+    As mentioned above, our `Search` app listens to the `bulk_post_create` and `bulk_post_delete`
+    signals and indexes/deleted documentation into Elasticsearch. The signal listeners are in
+    the `readthedocs/search/signals.py` file. Both of the signals are dispatched
+    after a successful documentation build.
+
+    The fields and ES Datatypes are specified in the `PageDocument`. The indexable data is taken
+    from `processed_json` property of `HTMLFile`. This property provides python dictionary with
+    document data like `title`, `headers`, `content` etc.
+
+
+.. _Elasticsearch: https://www.elastic.co/products/elasticsearch
+.. _Elasticsearch 6.3: https://www.elastic.co/guide/en/elasticsearch/reference/6.3/index.html
+.. _Github Repository: https://github.com/rtfd/readthedocs.org/tree/master/readthedocs/search
+.. _Elasticsearch document: https://www.elastic.co/guide/en/elasticsearch/guide/current/document.html
+.. _django-elasticsearch-dsl: https://github.com/sabricot/django-elasticsearch-dsl
+.. _elasticsearch-dsl: http://elasticsearch-dsl.readthedocs.io/en/latest/
+.. _Signals: https://docs.djangoproject.com/en/2.1/topics/signals/

docs/development/search.rst

@@ -95,6 +95,7 @@ Information about development is also available:
 
    changelog
    install
+   development/search
    architecture
    tests
    docs

docs/index.rst

@@ -57,7 +57,7 @@ need to install Python 2.7 with virtualenv in your system as well.
    If you want full support for searching inside your Read the Docs
    site you will need to install Elasticsearch_.
 
-   Ubuntu users could install this package by following :doc:`/custom_installs/elasticsearch`.
+   Follow :doc:`/development/search` documentation for more instruction.
 
 .. note::