The elastic-transport library provides a low-level Ruby client for connecting to an Elasticsearch cluster. It currently powers the Elasticsearch Ruby and the Enterprise Search Ruby clients.

When available, it handles connecting to multiple nodes in the cluster, rotating across connections, logging and tracing requests and responses, maintaining failed connections, discovering nodes in the cluster, and provides an abstraction for data serialization and transport.

It does not handle calling the Elasticsearch or Enterprise Search APIs.

For optimal performance, use a HTTP library which supports persistent ("keep-alive") connections, such as patron or Typhoeus. Require the library (require patron) in your code, and it will be automatically used.


Install the package from Rubygems:

gem install elastic-transport

To use an unreleased version, either add it to your Gemfile for Bundler:

gem 'elastic-transport', git: ''

or install it from a source code checkout:

git clone
cd elastic-transport
bundle install
rake install

Example usageedit

In the simplest form, connect to Elasticsearch running on http://localhost:9200 without any configuration:

require 'elastic/transport'

client =
response = client.perform_request('GET', '_cluster/health')
# => #<Elastic::Transport::Transport::Response:0x007fc5d506ce38 @status=200, @body={ ... } >

Full documentation is available at

Transport implementationsedit

By default, the client uses the Faraday HTTP library as a transport implementation.

It auto-detects and uses an adapter for Faraday based on gems loaded in your code, preferring HTTP clients with support for persistent connections.

To use the Patron HTTP, for example, require it:

require 'patron'

Then, create a new client, and the Patron gem will be used as the "driver":

client =

# => Faraday::Adapter::Patron

10.times do
  client.nodes.stats(metric: 'http')['nodes'].values.each do |n|
    puts "#{n['name']} : #{n['http']['total_opened']}"

# => Stiletoo : 24
# => Stiletoo : 24
# => Stiletoo : 24
# => ...

To use a specific adapter for Faraday, pass it as the adapter argument:

client = :net_http_persistent)

# => [Faraday::Adapter::NetHttpPersistent]

When using the Elasticsearch or Enterprise Search clients, you can pass the adapter parameter when initializing the clients.

To pass options to the Faraday::Connection constructor, use the transport_options key:

client =
  transport_options: {
    request: { open_timeout: 1 },
    headers: { user_agent:   'MyApp' },
    params:  { :format => 'yaml' },
    ssl:     { verify: false }

To configure the Faraday instance directly, use a block:

require 'patron'

client = 'localhost', port: '9200') do |f|
  f.response :logger
  f.adapter  :patron

You can use any standard Faraday middleware and plugins in the configuration block.

You can also initialize the transport class yourself, and pass it to the client constructor as the transport argument. The Elasticsearch and Enterprise Search clients accept :transport as parameter when initializing a client. So you can pass in a transport you’ve initialized with the following options:

require 'patron'

transport_configuration = lambda do |f|
  f.response :logger
  f.adapter  :patron

transport =
  hosts: [ { host: 'localhost', port: '9200' } ],

# Pass the transport to the client
client = transport)

Instead of passing the transport to the constructor, you can inject it at run time:

# Set up the transport
faraday_configuration = lambda do |f|
  f.instance_variable_set :@ssl, { verify: false }
  f.adapter :excon

faraday_client =
  hosts: [
      host: 'my-protected-host',
      port: '443',
      user: 'USERNAME',
      password: 'PASSWORD',
      scheme: 'https'

# Create a default client
client =

# Inject the transport to the client
client.transport = faraday_client

You can also use a bundled Curb based transport implementation:

require 'curb'
require 'elastic/transport/transport/http/curb'

client = Elastic::Transport::Transport::HTTP::Curb)

# => #<Curl::Easy http://localhost:9200/>

It’s possible to customize the Curb instance by passing a block to the constructor as well (in this case, as an inline block):

transport =
  hosts: [ { host: 'localhost', port: '9200' } ],
  & lambda { |c| c.verbose = true }

client = transport)

You can write your own transport implementation by including the {Elastic::Transport::Transport::Base} module, implementing the required contract, and passing it to the client as the transport_class parameter – or by injecting it directly.

Transport architectureedit

  • Elastic::Transport::Client is composed of Elastic::Transport::Transport.
  • Elastic::Transport::Transport is composed of Elastic::Transport::Transport::Connections, and an instance of logger, tracer, serializer and sniffer.
  • Logger and tracer can be any object conforming to Ruby logging interface, for example, an instance of Logger, log4r, logging, and so on.
  • The Elastic::Transport::Transport::Serializer::Base implementations handle converting data for Elasticsearch (for example, to JSON). You can implement your own serializer.
  • Elastic::Transport::Transport::Sniffer allows to discover nodes in the cluster and use them as connections.
  • Elastic::Transport::Transport::Connections::Collection is composed of Elastic::Transport::Transport::Connections::Connection instances and a selector instance.
  • Elastic::Transport::Transport::Connections::Connection contains the connection attributes such as hostname and port, as well as the concrete persistent "session" connected to a specific node.
  • The Elastic::Transport::Transport::Connections::Selector::Base implementations allow to choose connections from the pool, for example, in a round-robin or random fashion. You can implement your own selector strategy.