---
mapped_pages:
  - https://www.elastic.co/guide/en/elasticsearch/client/javascript-api/current/basic-config.html
---

# Basic configuration [basic-config]

This page shows you the possible basic configuration options that the clients offers.

```js
const { Client } = require("@elastic/elasticsearch");

const client = new Client({
  cloud: { id: "<cloud-id>" },
  auth: { apiKey: "base64EncodedKey" },
  maxRetries: 5,
  sniffOnStart: true,
});
```

|                   |                                                                                      |
| ----------------- | ------------------------------------------------------------------------------------ |
| `node` or `nodes` | The Elasticsearch endpoint to use. It can be a single string or an array of strings: |

```js
node: "http://localhost:9200";
```

Or it can be an object (or an array of objects) that represents the node:

```js
node: {
  url: new URL('http://localhost:9200'),
  tls: 'tls options',
  agent: 'http agent options',
  id: 'custom node id',
  headers: { 'custom': 'headers' }
  roles: {
    master: true,
    data: true,
    ingest: true,
    ml: false
  }
}
```

|
| `auth` | Your authentication data. You can use both basic authentication and [ApiKey](https://www.elastic.co/docs/api/doc/elasticsearch/operation/operation-security-create-api-key).
See [Authentication](/reference/connecting.md#authentication) for more details.
_Default:_ `null`

Basic authentication:

```js
auth: {
  username: 'elastic',
  password: 'changeme'
}
```

[ApiKey](https://www.elastic.co/docs/api/doc/elasticsearch/operation/operation-security-create-api-key) authentication:

```js
auth: {
  apiKey: "base64EncodedKey";
}
```

Bearer authentication, useful for [service account tokens](https://www.elastic.co/docs/api/doc/elasticsearch/operation/operation-security-create-service-token). Be aware that it does not handle automatic token refresh:

```js
auth: {
  bearer: "token";
}
```

|
| `maxRetries` | `number` - Max number of retries for each request.
_Default:_ `3` |
| `requestTimeout` | `number` - Max request timeout in milliseconds for each request.
_Default:_ No value |
| `pingTimeout` | `number` - Max ping request timeout in milliseconds for each request.
_Default:_ `3000` |
| `sniffInterval` | `number, boolean` - Perform a sniff operation every `n` milliseconds. Sniffing might not be the best solution for you, take a look [here](https://www.elastic.co/blog/elasticsearch-sniffing-best-practices-what-when-why-how) to know more.
_Default:_ `false` |
| `sniffOnStart` | `boolean` - Perform a sniff once the client is started. Sniffing might not be the best solution for you, take a look [here](https://www.elastic.co/blog/elasticsearch-sniffing-best-practices-what-when-why-how) to know more.
_Default:_ `false` |
| `sniffEndpoint` | `string` - Endpoint to ping during a sniff.
_Default:_ `'_nodes/_all/http'` |
| `sniffOnConnectionFault` | `boolean` - Perform a sniff on connection fault. Sniffing might not be the best solution for you, take a look [here](https://www.elastic.co/blog/elasticsearch-sniffing-best-practices-what-when-why-how) to know more.
_Default:_ `false` |
| `resurrectStrategy` | `string` - Configure the node resurrection strategy.
_Options:_ `'ping'`, `'optimistic'`, `'none'`
_Default:_ `'ping'` |
| `suggestCompression` | `boolean` - Adds `accept-encoding` header to every request.
_Default:_ `false` |
| `compression` | `string, boolean` - Enables gzip request body compression.
_Options:_ `'gzip'`, `false`
_Default:_ `false` |
| `tls` | `http.SecureContextOptions` - tls [configuraton](https://nodejs.org/api/tls.md).
_Default:_ `null` |
| `proxy` | `string, URL` - If you are using an http(s) proxy, you can put its url here. The client will automatically handle the connection to it.
_Default:_ `null`

```js
const client = new Client({
  node: "http://localhost:9200",
  proxy: "http://localhost:8080",
});

const client = new Client({
  node: "http://localhost:9200",
  proxy: "http://user:pwd@localhost:8080",
});
```

|
| `agent` | `http.AgentOptions, function` - http agent [options](https://nodejs.org/api/http.md#http_new_agent_options), or a function that returns an actual http agent instance. If you want to disable the http agent use entirely (and disable the `keep-alive` feature), set the agent to `false`.
_Default:_ `null`

```js
const client = new Client({
  node: "http://localhost:9200",
  agent: { agent: "options" },
});

const client = new Client({
  node: "http://localhost:9200",
  // the function takes as parameter the option
  // object passed to the Connection constructor
  agent: (opts) => new CustomAgent(),
});

const client = new Client({
  node: "http://localhost:9200",
  // Disable agent and keep-alive
  agent: false,
});
```

|

| `nodeFilter` | `function` - Filters which node not to use for a request.
_Default:_

```js
() => true;
```

|
| `nodeSelector` | `function` - custom selection strategy.
_Options:_ `'round-robin'`, `'random'`, custom function
_Default:_ `'round-robin'`
_Custom function example:_

```js
function nodeSelector(connections) {
  const index = calculateIndex();
  return connections[index];
}
```

|
| `generateRequestId` | `function` - function to generate the request id for every request, it takes two parameters, the request parameters and options.
By default it generates an incremental integer for every request.
_Custom function example:_

```js
function generateRequestId(params, options) {
  // your id generation logic
  // must be syncronous
  return "id";
}
```

|
| `name` | `string, symbol` - The name to identify the client instance in the events.
_Default:_ `elasticsearch-js` |
| `opaqueIdPrefix` | `string` - A string that will be use to prefix any `X-Opaque-Id` header.
See [`X-Opaque-Id` support](/reference/observability.md#_x_opaque_id_support) for more details.
\_Default:*`null` |
| `headers` | `object` - A set of custom headers to send in every request.
_Default:_ `{}` |
| `context` | `object` - A custom object that you can use for observability in your events.It will be merged with the API level context option.
_Default:_ `null` |
| `enableMetaHeader` | `boolean` - If true, adds an header named `'x-elastic-client-meta'`, containing some minimal telemetry data,such as the client and platform version.
_Default:_ `true` |
| `cloud` | `object` - Custom configuration for connecting to [Elastic Cloud](https://cloud.elastic.co). See [Authentication](/reference/connecting.md) for more details.
_Default:_ `null`
*Cloud configuration example:\*

```js
const client = new Client({
  cloud: {
    id: "<cloud-id>",
  },
  auth: {
    username: "elastic",
    password: "changeme",
  },
});
```

|
| `disablePrototypePoisoningProtection` | `boolean`, `'proto'`, `'constructor'` - The client can protect you against prototype poisoning attacks. Read [this article](https://web.archive.org/web/20200319091159/https://hueniverse.com/square-brackets-are-the-enemy-ff5b9fd8a3e8?gi=184a27ee2a08) to learn more about this security concern. If needed, you can enable prototype poisoning protection entirely (`false`) or one of the two checks (`'proto'` or `'constructor'`). For performance reasons, it is disabled by default. Read the `secure-json-parse` [documentation](https://github.com/fastify/secure-json-parse) to learn more.
_Default:_ `true` |
| `caFingerprint` | `string` - If configured, verify that the fingerprint of the CA certificate that has signed the certificate of the server matches the supplied fingerprint. Only accepts SHA256 digest fingerprints.
_Default:_ `null` |
| `maxResponseSize` | `number` - When configured, it verifies that the uncompressed response size is lower than the configured number, if it’s higher it will abort the request. It cannot be higher than buffer.constants.MAX*STRING_LENGTH
\_Default:* `null` |
| `maxCompressedResponseSize` | `number` - When configured, it verifies that the compressed response size is lower than the configured number, if it’s higher it will abort the request. It cannot be higher than buffer.constants.MAX*LENGTH
\_Default:* `null` |