== The Ruby Client

The `elasticsearch` http://rubygems.org/gems/elasticsearch[Rubygem] provides a low-level client
for communicating with an Elasticsearch cluster, fully compatible with other official clients.

Full documentation is hosted at https://github.com/elastic/elasticsearch-ruby[Github]
and http://rubydoc.info/gems/elasticsearch[RubyDoc]
-- this documentation provides only an overview of features.

=== Elasticsearch Version Compatibility

The Ruby API is compatible with both Elasticsearch 0.90.x and 1.0.x versions, you have to install
a matching http://rubygems.org/gems/elasticsearch/versions[gem version], though:

[cols="<,<",options="header",]
|=========================================
| Elasticsearch version | Ruby gem version
| 0.90.x                | 0.4.x
| 1.x                   | 1.x
|=========================================

=== Installation

Install the Ruby gem for Elasticsearch *1.x*:

[source,sh]
------------------------------------
gem install elasticsearch
------------------------------------

...or add it do your Gemfile:

[source,ruby]
------------------------------------
gem 'elasticsearch'
------------------------------------

Install the Ruby gem for Elasticsearch *0.90.x*:

[source,sh]
------------------------------------
gem install elasticsearch -v 0.4.10
------------------------------------

...or add it do your Gemfile:

[source,ruby]
------------------------------------
gem 'elasticsearch', '~> 0.4'
------------------------------------

=== Example Usage

[source,ruby]
------------------------------------
require 'elasticsearch'

client = Elasticsearch::Client.new log: true

client.cluster.health

client.index index: 'my-index', type: 'my-document', id: 1, body: { title: 'Test' }

client.indices.refresh index: 'my-index'

client.search index: 'my-index', body: { query: { match: { title: 'test' } } }
------------------------------------


=== Features at a Glance

* Pluggable logging and tracing
* Pluggable connection selection strategies (round-robin, random, custom)
* Pluggable transport implementation, customizable and extendable
* Pluggable serializer implementation
* Request retries and dead connections handling
* Node reloading (based on cluster state) on errors or on demand
* Modular API implementation
* 100% REST API coverage


=== Transport and API

The `elasticsearch` gem combines two separate Rubygems:

* https://github.com/elastic/elasticsearch-ruby/tree/master/elasticsearch-transport[`elasticsearch-transport`]
provides a HTTP Ruby client for connecting to the Elasticsearch cluster,

* https://github.com/elastic/elasticsearch-ruby/tree/master/elasticsearch-api[`elasticsearch-api`]
provides a Ruby API for the Elasticsearch RESTful API.

Please see their respective documentation for configuration options and technical details.

Notably, the documentation and comprehensive examples for all the API methods is contained in the source,
and available online at http://rubydoc.info/gems/elasticsearch-api/Elasticsearch/API/Actions[Rubydoc].

Keep in mind, that for optimal performance, you should use a HTTP library which supports
persistent ("keep-alive") HTTP connections.


=== Extensions

The https://github.com/elastic/elasticsearch-ruby/tree/master/elasticsearch-extensions[`elasticsearch-extensions`]
Rubygem provides a number of extensions to the core client, such as an API to programatically launch
Elasticsearch clusters (eg. for testing purposes), and more.

Please see its
https://github.com/elastic/elasticsearch-ruby/tree/master/elasticsearch-extensions[documentation]
for more information.