Add ability to set TCP keepalive

docs/api/Dispatcher.md

@@ -202,6 +202,7 @@ Returns: `Boolean` - `false` if dispatcher is busy and further dispatch calls wo
 * **bodyTimeout** `number | null` (optional) - The timeout after which a request will time out, in milliseconds. Monitors time between receiving body data. Use `0` to disable it entirely. Defaults to 30 seconds.
 * **headersTimeout** `number | null` (optional) - The amount of time the parser will wait to receive the complete HTTP headers while not sending the request. Defaults to 30 seconds.
 * **throwOnError** `boolean` (optional) - Default: `false` - Whether Undici should throw an error upon receiving a 4xx or 5xx response from the server.
+* **tcpKeepAliveInterval** `number | null` (optional) - Default: `60000` - TCP keepalive interval for the socket in milliseconds
 
 #### Parameter: `DispatchHandler`
 

lib/client.js

@@ -63,7 +63,8 @@ const {
   kDispatch,
   kInterceptors,
   kLocalAddress,
-  kMaxResponseSize
+  kMaxResponseSize,
+  kTcpKeepAliveInterval
 } = require('./core/symbols')
 
 const kClosedResolve = Symbol('kClosedResolve')
@@ -107,7 +108,8 @@ class Client extends DispatcherBase {
     connect,
     maxRequestsPerClient,
     localAddress,
-    maxResponseSize
+    maxResponseSize,
+    tcpKeepAliveInterval
   } = {}) {
     super()
 
@@ -163,6 +165,10 @@ class Client extends DispatcherBase {
       throw new InvalidArgumentError('bodyTimeout must be a positive integer or zero')
     }
 
+    if (tcpKeepAliveInterval != null && (!Number.isInteger(tcpKeepAliveInterval) || tcpKeepAliveInterval < 0)) {
+      throw new InvalidArgumentError('tcpKeepAliveInterval must be a positive integer or zero')
+    }
+
     if (connect != null && typeof connect !== 'function' && typeof connect !== 'object') {
       throw new InvalidArgumentError('connect must be a function or an object')
     }
@@ -212,6 +218,7 @@ class Client extends DispatcherBase {
     this[kHostHeader] = `host: ${this[kUrl].hostname}${this[kUrl].port ? `:${this[kUrl].port}` : ''}\r\n`
     this[kBodyTimeout] = bodyTimeout != null ? bodyTimeout : 30e3
     this[kHeadersTimeout] = headersTimeout != null ? headersTimeout : 30e3
+    this[kTcpKeepAliveInterval] = tcpKeepAliveInterval != null ? tcpKeepAliveInterval : 60e3
     this[kStrictContentLength] = strictContentLength == null ? true : strictContentLength
     this[kMaxRedirections] = maxRedirections
     this[kMaxRequests] = maxRequestsPerClient
@@ -1349,6 +1356,10 @@ function write (client, request) {
 
   const socket = client[kSocket]
 
+  if (client[kTcpKeepAliveInterval]) {
+    socket.setKeepAlive(true, client[kTcpKeepAliveInterval])
+  }
+
   try {
     request.onConnect((err) => {
       if (request.aborted || request.completed) {

lib/core/symbols.js

@@ -16,6 +16,7 @@ module.exports = {
   kKeepAlive: Symbol('keep alive'),
   kHeadersTimeout: Symbol('headers timeout'),
   kBodyTimeout: Symbol('body timeout'),
+  kTcpKeepAliveInterval: Symbol('tcp keep alive interval'),
   kServerName: Symbol('server name'),
   kLocalAddress: Symbol('local address'),
   kHost: Symbol('host'),

types/client.d.ts

@@ -43,6 +43,8 @@ declare namespace Client {
     maxRequestsPerClient?: number;
     /** Max response body size in bytes, -1 is disabled */
     maxResponseSize?: number | null;
+    /** TCP keepalive interval for the socket in milliseconds. Default: `60e3` milliseconds (60s) */
+    tcpKeepAliveInterval?: number | null;
 
     interceptors?: {Client: readonly DispatchInterceptor[] | undefined}
   }