---
title: Basic configuration
description: The table below contains the most important initialization parameters that you can use. 
url: https://www.elastic.co/elastic/docs-builder/docs/3028/reference/elasticsearch/clients/ruby/basic-config
products:
  - Elasticsearch
  - Elasticsearch Client
  - Elasticsearch Ruby Client
---

# Basic configuration
The table below contains the most important initialization parameters that you can use.

|                                 |                                        |                                                                                                                                                                                                                                                |
|---------------------------------|----------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| **Parameter**                   | **Data type**                          | **Description**                                                                                                                                                                                                                                |
| `adapter`                       | Symbol                                 | A specific adapter for Faraday (for example, `:patron`).                                                                                                                                                                                       |
| `api_key`                       | String, Hash                           | For API key Authentication. Either the base64 encoding of `id` and `api_key` joined by a colon as a string, or a hash with the `id` and `api_key` values.                                                                                      |
| `compression`                   | Boolean                                | Whether to compress requests. Gzip compression is used. Defaults to `false`. Responses are automatically inflated if they are compressed. If a custom transport object is used, it must handle the request compression and response inflation. |
| `enable_meta_header`            | Boolean                                | Whether to enable sending the meta data header to Cloud. Defaults to `true`.                                                                                                                                                                   |
| `hosts`                         | String, Array                          | Single host passed as a string or hash, or multiple hosts passed as an array; `host` or `url` keys are also valid.                                                                                                                             |
| `log`                           | Boolean                                | Whether to use the default logger. Disabled by default.                                                                                                                                                                                        |
| `logger`                        | Object                                 | An instance of a Logger-compatible object.                                                                                                                                                                                                     |
| `opaque_id_prefix`              | String                                 | Sets a prefix for X-Opaque-Id when initializing the client. This is prepended to the id you set before each request if you’re using X-Opaque-Id.                                                                                               |
| `opentelemetry_tracer_provider` | `OpenTelemetry::Trace::TracerProvider` | An explicit TracerProvider to use instead of the global one with OpenTelemetry. This enables better dependency injection and simplifies testing.                                                                                               |
| `randomize_hosts`               | Boolean                                | Whether to shuffle connections on initialization and reload. Defaults to `false`.                                                                                                                                                              |
| `reload_connections`            | Boolean, Number                        | Whether to reload connections after X requests. Defaults to `false`.                                                                                                                                                                           |
| `reload_on_failure`             | Boolean                                | Whether to reload connections after failure. Defaults to `false`.                                                                                                                                                                              |
| `request_timeout`               | Integer                                | The request timeout to be passed to transport in options.                                                                                                                                                                                      |
| `resurrect_after`               | Integer                                | Specifies after how many seconds a dead connection should be tried again.                                                                                                                                                                      |
| `retry_on_failure`              | Boolean, Number                        | Whether to retry X times when request fails before raising and exception. Defaults to `false`.                                                                                                                                                 |
| `retry_on_status`               | Array, Number                          | Specifies which status code needs to be returned to retry.                                                                                                                                                                                     |
| `selector`                      | Constant                               | An instance of selector strategy implemented with {Elastic::Transport::Transport::Connections::Selector::Base}.                                                                                                                                |
| `send_get_body_as`              | String                                 | Specifies the HTTP method to use for GET requests with a body. Defaults to `GET`.                                                                                                                                                              |
| `serializer_class`              | Constant                               | Specifies a serializer class to use. It is initialized by the transport and passed the transport instance.                                                                                                                                     |
| `sniffer_timeout`               | Integer                                | Specifies the timeout for reloading connections in seconds. Defaults to `1`.                                                                                                                                                                   |
| `trace`                         | Boolean                                | Whether to use the default tracer. Disabled by default.                                                                                                                                                                                        |
| `tracer`                        | Object                                 | Specifies an instance of a Logger-compatible object.                                                                                                                                                                                           |
| `transport`                     | Object                                 | Specifies a transport instance.                                                                                                                                                                                                                |
| `transport_class`               | Constant                               | Specifies a transport class to use. It is initialized by the client and passed hosts and all arguments.                                                                                                                                        |
| `transport_options`             | Hash                                   | Specifies the options to be passed to the `Faraday::Connection` constructor.                                                                                                                                                                   |