projektuebersicht/node_modules/undici/docs/docs/api/Client.md

Client

Stability: 2 - Stable

A basic HTTP/1.1 client mapped on top of a single TCP/TLS connection. When the server supports HTTP/2 and selects it during ALPN negotiation, the same connection is used for HTTP/2. Pipelining is disabled by default.

Client extends Dispatcher and is the lowest-level dispatcher in undici: it manages exactly one origin over one connection. For pooling across multiple connections use Pool, and for routing across multiple origins use Agent. Requests are not guaranteed to be dispatched in the order in which they are invoked.

import { Client } from 'undici'

const client = new Client('http://localhost:3000')
const { statusCode, body } = await client.request({ path: '/', method: 'GET' })

Class: Client

• Extends: {Dispatcher}

new Client(url[, options])

• url {URL|string} The origin to connect to. Only the protocol, hostname, and port are used.
• options {Object} (optional)
  • bodyTimeout {number|null} The timeout, in milliseconds, after which a request times out while receiving body data. Monitors the time between consecutive body chunks. Use 0 to disable it entirely. Default: 300e3.
  • headersTimeout {number|null} The timeout, in milliseconds, the parser waits to receive the complete HTTP headers before the request times out. Use 0 to disable it entirely. Default: 300e3. HTTP/1.1 headers/body parser timeouts are not guaranteed to fire with exact millisecond precision: delays up to 1000ms use native timers, while larger delays use undici's lower-overhead fast timers with a target resolution around 500ms.
  • connectTimeout {number|null} The timeout, in milliseconds, for establishing a socket connection. Use 0 to disable it entirely. Default: 10e3.
  • keepAliveTimeout {number|null} The timeout, in milliseconds, after which a socket with no active requests times out. Monitors the time between activity on a connected socket. This value may be overridden by keep-alive hints from the server. Default: 4e3.
  • keepAliveMaxTimeout {number|null} The maximum allowed keepAliveTimeout, in milliseconds, when overridden by keep-alive hints from the server. Default: 600e3.
  • keepAliveTimeoutThreshold {number|null} A number of milliseconds subtracted from server keep-alive hints when overriding keepAliveTimeout, to account for timing inaccuracies caused by e.g. transport latency. Default: 2e3.
  • maxHeaderSize {number|null} The maximum length of request headers, in bytes. Default: the value of Node.js' --max-http-header-size or 16384 (16 KiB).
  • maxResponseSize {number|null} The maximum length of a response body, in bytes. Set to -1 to disable it. Default: -1.
  • maxRequestsPerClient {number|null} The maximum number of requests to send over a single connection before the socket is reset. Use 0 to disable this limit. Default: null.
  • localAddress {string|null} The local IP address the socket should connect from. Default: null.
  • pipelining {number|null} The number of concurrent requests sent over the single connection, per RFC 7230, section 6.3.2. Only enable values greater than 1 when the remote server is trusted. Set to 0 to disable keep-alive connections. Has no effect once HTTP/2 is negotiated; see maxConcurrentStreams for the HTTP/2 dispatch ceiling. Default: 1.
  • connect {Object|Function|null} Configures how connections are established. Either a ConnectOptions object passed to the built-in buildConnector (every [tls.connect()][] option is accepted, plus the fields below), or a custom connector function with the signature (options, callback). Default: null.
    • socketPath {string|null} An IPC endpoint, either a Unix domain socket or a Windows named pipe. Default: null.
    • maxCachedSessions {number|null} The maximum number of cached TLS sessions. Use 0 to disable TLS session caching. Default: 100.
    • timeout {number|null} The connection timeout, in milliseconds. Default: 10e3.
    • servername {string|null} The TLS server name used for SNI.
    • keepAlive {boolean|null} Whether TCP keep-alive is enabled on the socket. Default: true.
    • keepAliveInitialDelay {number|null} The TCP keep-alive interval for the socket, in milliseconds. Default: 60000.
  • strictContentLength {boolean} Whether to throw when the request content-length header does not match the length of the request body. Disabling this exposes the application to HTTP request smuggling; only do so in controlled environments where the request source is fully trusted. Default: true.
  • autoSelectFamily {boolean} Enables a family autodetection algorithm that loosely implements section 5 of RFC 8305. Ignored if unsupported by the current Node.js version. Default: false.
  • autoSelectFamilyAttemptTimeout {number} The time, in milliseconds, to wait for a connection attempt to finish before trying the next address when autoSelectFamily is enabled. Default: 250.
  • allowH2 {boolean} Enables HTTP/2 support when the server assigns it a higher priority through ALPN negotiation. Default: true.
  • useH2c {boolean} Deprecated: use h2Options.useH2c instead Enforces h2c (HTTP/2 cleartext) for non-HTTPS connections. Default: false.
  • maxConcurrentStreams {number} Deprecated: use h2Options.useH2c instead The maximum number of concurrent HTTP/2 streams for a single session. Once h2 is negotiated this — not pipelining, which is HTTP/1.1 only — is the ceiling used to dispatch in-flight requests. It may be overridden by the server's SETTINGS_MAX_CONCURRENT_STREAMS frame. Default: 100.
  • connectionWindowSize {number} Deprecated: use h2Options.connectionWindowSize instead The HTTP/2 connection-level flow-control window size set via ClientHttp2Session.setLocalWindowSize(). Must be a positive integer. Default: 524288.
  • pingInterval {number} Deprecated: use h2Options.pingInterval instead The time interval, in milliseconds, between HTTP/2 PING frames. Set to 0 to disable PING frames. Applies only to HTTP/2 connections and emits a ping event on the client. Default: 60e3.
  • h2Options {object} Set of options for HTTP/2 sessions
    • useH2c {boolean} Enforces h2c (HTTP/2 cleartext) for non-HTTPS connections. Default: false.
    • maxConcurrentStreams {number} The maximum number of concurrent HTTP/2 streams for a single session. Once h2 is negotiated this — not pipelining, which is HTTP/1.1 only — is the ceiling used to dispatch in-flight requests. It may be overridden by the server's SETTINGS_MAX_CONCURRENT_STREAMS frame. Default: 100.
    • connectionWindowSize {number} The HTTP/2 connection-level flow-control window size set via ClientHttp2Session.setLocalWindowSize(). Must be a positive integer. Default: 524288.
    • pingInterval {number} The time interval, in milliseconds, between HTTP/2 PING frames. Set to 0 to disable PING frames. Applies only to HTTP/2 connections and emits a ping event on the client. Default: 60e3.
    • settings {object} SETTINGS frame options. For full reference, take a look to HTTP/2#Settings Object
  • webSocket {Object} (optional) WebSocket-specific configuration.
    • maxFragments {number} The maximum number of fragments in a message. Set to 0 to disable the limit. Default: 131072.
    • maxPayloadSize {number} The maximum allowed payload size, in bytes, for WebSocket messages. Applied to uncompressed messages, compressed frame payloads, and decompressed (permessage-deflate) messages. Set to 0 to disable the limit. Default: 134217728.
  • eventSource {Object} (optional) EventSource-specific configuration.
    • maxEventSize {number} The maximum allowed event size, in bytes, for EventSource messages. Set to 0 to disable the limit. Default: buffer.kStringMaxLength.
• Returns: {Client}

Instantiating a Client does not open a connection; the connection is established lazily once a request is queued. Call client.connect() to connect eagerly.

Notes about HTTP/2:

• Pseudo headers (:path, :method, :scheme, :authority) are attached automatically and overwrite any user-provided values.
• The server must support HTTP/2 and select it during ALPN negotiation, and must not give HTTP/1.1 a higher priority than HTTP/2.
• PUSH frames are not supported.

import { Client } from 'undici'

const client = new Client('http://localhost:3000')

import { Client } from 'undici'
import { readFileSync } from 'node:fs'

const client = new Client('https://localhost:3000', {
  connect: {
    rejectUnauthorized: false,
    ca: readFileSync('./ca-cert.pem')
  }
})

import { Client } from 'undici'

const client = new Client('http://localhost:3000', {
  connect: {
    socketPath: '/var/run/docker.sock'
  }
})

import { Client } from 'undici'
import dns from 'node:dns'

const client = new Client('https://example.com', {
  connect: {
    lookup (hostname, options, callback) {
      dns.lookup(hostname, { ...options, family: 4 }, callback)
    }
  }
})

import { Client, buildConnector } from 'undici'

const connector = buildConnector({ rejectUnauthorized: false })
const client = new Client('https://localhost:3000', {
  connect (opts, cb) {
    connector(opts, (err, socket) => {
      if (err) {
        cb(err)
      } else {
        cb(null, socket)
      }
    })
  }
})

When a connector function is provided, undici wraps it to automatically inject socketPath and allowH2 into the options argument when those values are set on the client. See Connector for details on building custom connectors.

client.close([callback])

Implements [dispatcher.close([callback])][]. Closes the client gracefully, waiting for enqueued requests to complete before resolving.

client.destroy([error[, callback]])

Implements [dispatcher.destroy([error[, callback]])][]. Destroys the client abruptly, aborting all pending and running requests, and waits until the socket is closed before invoking callback (or resolving the returned promise).

client.connect(options[, callback])

• options {Object} The connect options, identical to [dispatcher.connect()][] except that origin is omitted because the client is bound to a single origin.
• callback {Function} (optional)
• Returns: {Promise|void} A promise when callback is not provided.

Starts a connection to the client's origin and tunnels a connection through it, as defined by [dispatcher.connect()][].

client.dispatch(options, handlers)

Implements [dispatcher.dispatch(options, handler)][]. This is the lowest-level API used by all other request methods; prefer client.request() for most use cases.

client.pipeline(options, handler)

See [dispatcher.pipeline(options, handler)][]. Sends a request and returns a {Duplex} stream that the request body is written to and the response body is read from.

client.request(options[, callback])

• options {Object}
• callback {Function} (optional)
• Returns: {Promise|void} A promise resolving to the response data when callback is not provided.

See [dispatcher.request(options[, callback])][]. Performs an HTTP request and returns its status code, headers, trailers, and a readable body stream.

import { Client } from 'undici'

const client = new Client('http://localhost:3000')
const { statusCode, headers, body } = await client.request({
  path: '/',
  method: 'GET'
})

console.log(statusCode)
for await (const chunk of body) {
  console.log(chunk.toString())
}

client.stream(options, factory[, callback])

• options {Object}
• factory {Function} Returns a {Writable} the response body is piped into.
• callback {Function} (optional)
• Returns: {Promise|void} A promise when callback is not provided.

See [dispatcher.stream(options, factory[, callback])][]. A faster alternative to client.request() when the destination of the response body is known in advance.

client.upgrade(options[, callback])

• options {Object}
• callback {Function} (optional)
• Returns: {Promise|void} A promise when callback is not provided.

See [dispatcher.upgrade(options[, callback])][]. Upgrades a connection to a different protocol, such as for WebSocket or HTTP CONNECT.

client.closed

• Type: {boolean}

true after client.close() has been called.

client.destroyed

• Type: {boolean}

true after client.destroy() has been called, or after client.close() has been called and the client shutdown has completed.

client.pipelining

• Type: {number}

The pipelining factor. This property can be read and written to adjust the number of concurrent requests sent over the connection. Only enable pipelining with trusted remote servers.

client.stats

• Type: {ClientStats}

Aggregate statistics for the client. See ClientStats.

Event: 'connect'

• origin {URL}
• targets {Array}

Emitted when a socket has been created and connected. The client connects once client.size > 0. See Dispatcher Event: 'connect'.

import { createServer } from 'node:http'
import { Client } from 'undici'
import { once } from 'node:events'

const server = createServer((request, response) => {
  response.end('Hello, World!')
}).listen()

await once(server, 'listening')

const client = new Client(`http://localhost:${server.address().port}`)

client.on('connect', (origin) => {
  console.log(`Connected to ${origin}`)
})

const { body } = await client.request({ path: '/', method: 'GET' })
body.setEncoding('utf8')
body.on('data', console.log)

client.close()
server.close()

Event: 'disconnect'

• origin {URL}
• targets {Array}
• error {Error}

Emitted when a socket has disconnected. The error argument is the error that caused the disconnection. The client reconnects if or once client.size > 0. See Dispatcher Event: 'disconnect'.

import { createServer } from 'node:http'
import { Client } from 'undici'
import { once } from 'node:events'

const server = createServer((request, response) => {
  response.destroy()
}).listen()

await once(server, 'listening')

const client = new Client(`http://localhost:${server.address().port}`)

client.on('disconnect', (origin) => {
  console.log(`Disconnected from ${origin}`)
})

try {
  await client.request({ path: '/', method: 'GET' })
} catch (error) {
  console.error(error.message)
} finally {
  client.close()
  server.close()
}

Event: 'drain'

• origin {URL}

Emitted when the pipeline is no longer busy. See Dispatcher Event: 'drain'.

import { createServer } from 'node:http'
import { Client } from 'undici'
import { once } from 'node:events'

const server = createServer((request, response) => {
  response.end('Hello, World!')
}).listen()

await once(server, 'listening')

const client = new Client(`http://localhost:${server.address().port}`)

client.on('drain', () => {
  console.log('drain event')
  client.close()
  server.close()
})

await Promise.all([
  client.request({ path: '/', method: 'GET' }),
  client.request({ path: '/', method: 'GET' }),
  client.request({ path: '/', method: 'GET' })
])

Event: 'error'

• error {Error}

Emitted for user errors, such as throwing inside an onResponseError handler.

[dispatcher.close([callback])]: Dispatcher.md#dispatcherclosecallback [dispatcher.connect()]: Dispatcher.md#dispatcherconnectoptions-callback [dispatcher.destroy([error[, callback]])]: Dispatcher.md#dispatcherdestroyerror-callback [dispatcher.dispatch(options, handler)]: Dispatcher.md#dispatcherdispatchoptions-handler [dispatcher.pipeline(options, handler)]: Dispatcher.md#dispatcherpipelineoptions-handler [dispatcher.request(options[, callback])]: Dispatcher.md#dispatcherrequestoptions-callback [dispatcher.stream(options, factory[, callback])]: Dispatcher.md#dispatcherstreamoptions-factory-callback [dispatcher.upgrade(options[, callback])]: Dispatcher.md#dispatcherupgradeoptions-callback [tls.connect()]: https://nodejs.org/api/tls.html#tlsconnectoptions-callback