Add Webhook response node (#2254)

* ✨ Add Webhook-Response-Node

* ⚡ Replace callback function with promise

* ✨ Add support for Bull and binary-data

* ✨ Add string response option

* ⚡ Remove some comments

* ✨ Make more generically possible & fix issue multi call in
queue mode

* ⚡ Fix startup and eslint issues

* ⚡ Improvements to webhook response node and functionality

* ⚡ Replace data with more generic type

* ⚡ Make statusMessage optional

* ⚡ Change parameter order

* ⚡ Move Response Code underneath options

* ⚡ Hide Response Code on Webhook node if mode responseNode got selected

* ⚡ Minor improvements

* ⚡ Add missing file and fix lint issue

* ⚡ Fix some node linting issues

* ⚡ Apply feedback

* ⚡ Minor improvements

packages/cli/commands/worker.ts

@@ -12,7 +12,7 @@ import * as PCancelable from 'p-cancelable';
 import { Command, flags } from '@oclif/command';
 import { UserSettings, WorkflowExecute } from 'n8n-core';
 
-import { INodeTypes, IRun, Workflow, LoggerProxy } from 'n8n-workflow';
+import { IExecuteResponsePromiseData, INodeTypes, IRun, Workflow, LoggerProxy } from 'n8n-workflow';
 
 import { FindOneOptions } from 'typeorm';
 
@@ -25,11 +25,13 @@ import {
 	GenericHelpers,
 	IBullJobData,
 	IBullJobResponse,
+	IBullWebhookResponse,
 	IExecutionFlattedDb,
 	InternalHooksManager,
 	LoadNodesAndCredentials,
 	NodeTypes,
 	ResponseHelper,
+	WebhookHelpers,
 	WorkflowExecuteAdditionalData,
 } from '../src';
 
@@ -172,6 +174,16 @@ export class Worker extends Command {
 			currentExecutionDb.workflowData,
 			{ retryOf: currentExecutionDb.retryOf as string },
 		);
+
+		additionalData.hooks.hookFunctions.sendResponse = [
+			async (response: IExecuteResponsePromiseData): Promise<void> => {
+				await job.progress({
+					executionId: job.data.executionId as string,
+					response: WebhookHelpers.encodeWebhookResponse(response),
+				} as IBullWebhookResponse);
+			},
+		];
+
 		additionalData.executionId = jobData.executionId;
 
 		let workflowExecute: WorkflowExecute;

packages/cli/src/ActiveExecutions.ts

@@ -5,9 +5,12 @@
 /* eslint-disable @typescript-eslint/no-unsafe-call */
 /* eslint-disable @typescript-eslint/no-non-null-assertion */
 /* eslint-disable @typescript-eslint/no-unsafe-assignment */
-import { IRun } from 'n8n-workflow';
-
-import { createDeferredPromise } from 'n8n-core';
+import {
+	createDeferredPromise,
+	IDeferredPromise,
+	IExecuteResponsePromiseData,
+	IRun,
+} from 'n8n-workflow';
 
 import { ChildProcess } from 'child_process';
 // eslint-disable-next-line import/no-extraneous-dependencies
@@ -116,6 +119,28 @@ export class ActiveExecutions {
 		this.activeExecutions[executionId].workflowExecution = workflowExecution;
 	}
 
+	attachResponsePromise(
+		executionId: string,
+		responsePromise: IDeferredPromise<IExecuteResponsePromiseData>,
+	): void {
+		if (this.activeExecutions[executionId] === undefined) {
+			throw new Error(
+				`No active execution with id "${executionId}" got found to attach to workflowExecution to!`,
+			);
+		}
+
+		this.activeExecutions[executionId].responsePromise = responsePromise;
+	}
+
+	resolveResponsePromise(executionId: string, response: IExecuteResponsePromiseData): void {
+		if (this.activeExecutions[executionId] === undefined) {
+			return;
+		}
+
+		// eslint-disable-next-line @typescript-eslint/no-unsafe-member-access
+		this.activeExecutions[executionId].responsePromise?.resolve(response);
+	}
+
 	/**
 	 * Remove an active execution
 	 *
@@ -193,6 +218,7 @@ export class ActiveExecutions {
 
 		this.activeExecutions[executionId].postExecutePromises.push(waitPromise);
 
+		// eslint-disable-next-line @typescript-eslint/no-unsafe-return, @typescript-eslint/no-unsafe-member-access
 		return waitPromise.promise();
 	}
 

packages/cli/src/ActiveWorkflowRunner.ts

@@ -12,7 +12,9 @@
 import { ActiveWorkflows, NodeExecuteFunctions } from 'n8n-core';
 
 import {
+	IDeferredPromise,
 	IExecuteData,
+	IExecuteResponsePromiseData,
 	IGetExecutePollFunctions,
 	IGetExecuteTriggerFunctions,
 	INode,
@@ -40,8 +42,6 @@ import {
 	NodeTypes,
 	ResponseHelper,
 	WebhookHelpers,
-	// eslint-disable-next-line @typescript-eslint/no-unused-vars
-	WorkflowCredentials,
 	WorkflowExecuteAdditionalData,
 	WorkflowHelpers,
 	WorkflowRunner,
@@ -550,6 +550,7 @@ export class ActiveWorkflowRunner {
 		data: INodeExecutionData[][],
 		additionalData: IWorkflowExecuteAdditionalDataWorkflow,
 		mode: WorkflowExecuteMode,
+		responsePromise?: IDeferredPromise<IExecuteResponsePromiseData>,
 	) {
 		const nodeExecutionStack: IExecuteData[] = [
 			{
@@ -580,7 +581,7 @@ export class ActiveWorkflowRunner {
 		};
 
 		const workflowRunner = new WorkflowRunner();
-		return workflowRunner.run(runData, true);
+		return workflowRunner.run(runData, true, undefined, undefined, responsePromise);
 	}
 
 	/**
@@ -641,13 +642,16 @@ export class ActiveWorkflowRunner {
 				mode,
 				activation,
 			);
-			returnFunctions.emit = (data: INodeExecutionData[][]): void => {
+			returnFunctions.emit = (
+				data: INodeExecutionData[][],
+				responsePromise?: IDeferredPromise<IExecuteResponsePromiseData>,
+			): void => {
 				// eslint-disable-next-line @typescript-eslint/restrict-template-expressions
 				Logger.debug(`Received trigger for workflow "${workflow.name}"`);
 				WorkflowHelpers.saveStaticData(workflow);
 				// eslint-disable-next-line id-denylist
-				this.runWorkflow(workflowData, node, data, additionalData, mode).catch((err) =>
-					console.error(err),
+				this.runWorkflow(workflowData, node, data, additionalData, mode, responsePromise).catch(
+					(error) => console.error(error),
 				);
 			};
 			return returnFunctions;

packages/cli/src/Interfaces.ts

@@ -7,19 +7,19 @@ import {
 	ICredentialsEncrypted,
 	ICredentialType,
 	IDataObject,
+	IDeferredPromise,
+	IExecuteResponsePromiseData,
 	IRun,
 	IRunData,
 	IRunExecutionData,
 	ITaskData,
 	ITelemetrySettings,
 	IWorkflowBase as IWorkflowBaseWorkflow,
-	// eslint-disable-next-line @typescript-eslint/no-unused-vars
-	IWorkflowCredentials,
 	Workflow,
 	WorkflowExecuteMode,
 } from 'n8n-workflow';
 
-import { IDeferredPromise, WorkflowExecute } from 'n8n-core';
+import { WorkflowExecute } from 'n8n-core';
 
 // eslint-disable-next-line import/no-extraneous-dependencies
 import * as PCancelable from 'p-cancelable';
@@ -47,6 +47,11 @@ export interface IBullJobResponse {
 	success: boolean;
 }
 
+export interface IBullWebhookResponse {
+	executionId: string;
+	response: IExecuteResponsePromiseData;
+}
+
 export interface ICustomRequest extends Request {
 	parsedUrl: Url | undefined;
 }
@@ -237,6 +242,7 @@ export interface IExecutingWorkflowData {
 	process?: ChildProcess;
 	startedAt: Date;
 	postExecutePromises: Array<IDeferredPromise<IRun | undefined>>;
+	responsePromise?: IDeferredPromise<IExecuteResponsePromiseData>;
 	workflowExecution?: PCancelable<IRun>;
 }
 
@@ -490,6 +496,7 @@ export interface IPushDataConsoleMessage {
 
 export interface IResponseCallbackData {
 	data?: IDataObject | IDataObject[];
+	headers?: object;
 	noWebhookResponse?: boolean;
 	responseCode?: number;
 }

packages/cli/src/Queue.ts

@@ -1,12 +1,21 @@
+/* eslint-disable @typescript-eslint/no-unsafe-member-access */
 import * as Bull from 'bull';
 import * as config from '../config';
 // eslint-disable-next-line import/no-cycle
-import { IBullJobData } from './Interfaces';
+import { IBullJobData, IBullWebhookResponse } from './Interfaces';
+// eslint-disable-next-line import/no-cycle
+import * as ActiveExecutions from './ActiveExecutions';
+// eslint-disable-next-line import/no-cycle
+import * as WebhookHelpers from './WebhookHelpers';
 
 export class Queue {
+	private activeExecutions: ActiveExecutions.ActiveExecutions;
+
 	private jobQueue: Bull.Queue;
 
 	constructor() {
+		this.activeExecutions = ActiveExecutions.getInstance();
+
 		const prefix = config.get('queue.bull.prefix') as string;
 		const redisOptions = config.get('queue.bull.redis') as object;
 		// Disabling ready check is necessary as it allows worker to
@@ -16,6 +25,14 @@ export class Queue {
 		// More here: https://github.com/OptimalBits/bull/issues/890
 		// @ts-ignore
 		this.jobQueue = new Bull('jobs', { prefix, redis: redisOptions, enableReadyCheck: false });
+
+		this.jobQueue.on('global:progress', (jobId, progress: IBullWebhookResponse) => {
+			this.activeExecutions.resolveResponsePromise(
+				// eslint-disable-next-line @typescript-eslint/no-unsafe-member-access
+				progress.executionId,
+				WebhookHelpers.decodeWebhookResponse(progress.response),
+			);
+		});
 	}
 
 	async add(jobData: IBullJobData, jobOptions: object): Promise<Bull.Job> {

packages/cli/src/ResponseHelper.ts

@@ -72,11 +72,16 @@ export function sendSuccessResponse(
 	data: any,
 	raw?: boolean,
 	responseCode?: number,
+	responseHeader?: object,
 ) {
 	if (responseCode !== undefined) {
 		res.status(responseCode);
 	}
 
+	if (responseHeader) {
+		res.header(responseHeader);
+	}
+
 	if (raw === true) {
 		if (typeof data === 'string') {
 			res.send(data);

packages/cli/src/Server.ts

@@ -2669,7 +2669,13 @@ class App {
 					return;
 				}
 
-				ResponseHelper.sendSuccessResponse(res, response.data, true, response.responseCode);
+				ResponseHelper.sendSuccessResponse(
+					res,
+					response.data,
+					true,
+					response.responseCode,
+					response.headers,
+				);
 			},
 		);
 
@@ -2720,7 +2726,13 @@ class App {
 					return;
 				}
 
-				ResponseHelper.sendSuccessResponse(res, response.data, true, response.responseCode);
+				ResponseHelper.sendSuccessResponse(
+					res,
+					response.data,
+					true,
+					response.responseCode,
+					response.headers,
+				);
 			},
 		);
 
@@ -2746,7 +2758,13 @@ class App {
 					return;
 				}
 
-				ResponseHelper.sendSuccessResponse(res, response.data, true, response.responseCode);
+				ResponseHelper.sendSuccessResponse(
+					res,
+					response.data,
+					true,
+					response.responseCode,
+					response.headers,
+				);
 			},
 		);
 

packages/cli/src/WebhookHelpers.ts

@@ -1,3 +1,4 @@
+/* eslint-disable @typescript-eslint/no-unsafe-call */
 /* eslint-disable no-param-reassign */
 /* eslint-disable @typescript-eslint/prefer-optional-chain */
 /* eslint-disable @typescript-eslint/no-shadow */
@@ -18,9 +19,13 @@ import { get } from 'lodash';
 import { BINARY_ENCODING, NodeExecuteFunctions } from 'n8n-core';
 
 import {
+	createDeferredPromise,
 	IBinaryKeyData,
 	IDataObject,
+	IDeferredPromise,
 	IExecuteData,
+	IExecuteResponsePromiseData,
+	IN8nHttpFullResponse,
 	INode,
 	IRunExecutionData,
 	IWebhookData,
@@ -34,20 +39,20 @@ import {
 } from 'n8n-workflow';
 // eslint-disable-next-line import/no-cycle
 import {
-	ActiveExecutions,
 	GenericHelpers,
 	IExecutionDb,
 	IResponseCallbackData,
 	IWorkflowDb,
 	IWorkflowExecutionDataProcess,
 	ResponseHelper,
-	// eslint-disable-next-line @typescript-eslint/no-unused-vars
-	WorkflowCredentials,
 	WorkflowExecuteAdditionalData,
 	WorkflowHelpers,
 	WorkflowRunner,
 } from '.';
 
+// eslint-disable-next-line import/no-cycle
+import * as ActiveExecutions from './ActiveExecutions';
+
 const activeExecutions = ActiveExecutions.getInstance();
 
 /**
@@ -91,6 +96,35 @@ export function getWorkflowWebhooks(
 	return returnData;
 }
 
+export function decodeWebhookResponse(
+	response: IExecuteResponsePromiseData,
+): IExecuteResponsePromiseData {
+	if (
+		typeof response === 'object' &&
+		typeof response.body === 'object' &&
+		(response.body as IDataObject)['__@N8nEncodedBuffer@__']
+	) {
+		response.body = Buffer.from(
+			(response.body as IDataObject)['__@N8nEncodedBuffer@__'] as string,
+			BINARY_ENCODING,
+		);
+	}
+
+	return response;
+}
+
+export function encodeWebhookResponse(
+	response: IExecuteResponsePromiseData,
+): IExecuteResponsePromiseData {
+	if (typeof response === 'object' && Buffer.isBuffer(response.body)) {
+		response.body = {
+			'__@N8nEncodedBuffer@__': response.body.toString(BINARY_ENCODING),
+		};
+	}
+
+	return response;
+}
+
 /**
  * Returns all the webhooks which should be created for the give workflow
  *
@@ -169,7 +203,7 @@ export async function executeWebhook(
 		200,
 	) as number;
 
-	if (!['onReceived', 'lastNode'].includes(responseMode as string)) {
+	if (!['onReceived', 'lastNode', 'responseNode'].includes(responseMode as string)) {
 		// If the mode is not known we error. Is probably best like that instead of using
 		// the default that people know as early as possible (probably already testing phase)
 		// that something does not resolve properly.
@@ -356,9 +390,52 @@ export async function executeWebhook(
 			workflowData,
 		};
 
+		let responsePromise: IDeferredPromise<IN8nHttpFullResponse> | undefined;
+		if (responseMode === 'responseNode') {
+			responsePromise = await createDeferredPromise<IN8nHttpFullResponse>();
+			responsePromise
+				.promise()
+				.then((response: IN8nHttpFullResponse) => {
+					if (didSendResponse) {
+						return;
+					}
+
+					if (Buffer.isBuffer(response.body)) {
+						res.header(response.headers);
+						res.end(response.body);
+
+						responseCallback(null, {
+							noWebhookResponse: true,
+						});
+					} else {
+						// TODO: This probably needs some more changes depending on the options on the
+						//       Webhook Response node
+						responseCallback(null, {
+							data: response.body as IDataObject,
+							headers: response.headers,
+							responseCode: response.statusCode,
+						});
+					}
+
+					didSendResponse = true;
+				})
+				.catch(async (error) => {
+					Logger.error(
+						`Error with Webhook-Response for execution "${executionId}": "${error.message}"`,
+						{ executionId, workflowId: workflow.id },
+					);
+				});
+		}
+
 		// Start now to run the workflow
 		const workflowRunner = new WorkflowRunner();
-		executionId = await workflowRunner.run(runData, true, !didSendResponse, executionId);
+		executionId = await workflowRunner.run(
+			runData,
+			true,
+			!didSendResponse,
+			executionId,
+			responsePromise,
+		);
 
 		Logger.verbose(
 			`Started execution of workflow "${workflow.name}" from webhook with execution ID ${executionId}`,
@@ -398,6 +475,20 @@ export async function executeWebhook(
 					return data;
 				}
 
+				if (responseMode === 'responseNode') {
+					if (!didSendResponse) {
+						// Return an error if no Webhook-Response node did send any data
+						responseCallback(null, {
+							data: {
+								message: 'Workflow executed sucessfully.',
+							},
+							responseCode,
+						});
+						didSendResponse = true;
+					}
+					return undefined;
+				}
+
 				if (returnData === undefined) {
 					if (!didSendResponse) {
 						responseCallback(null, {

packages/cli/src/WebhookServer.ts

@@ -64,7 +64,13 @@ export function registerProductionWebhooks() {
 				return;
 			}
 
-			ResponseHelper.sendSuccessResponse(res, response.data, true, response.responseCode);
+			ResponseHelper.sendSuccessResponse(
+				res,
+				response.data,
+				true,
+				response.responseCode,
+				response.headers,
+			);
 		},
 	);
 
@@ -115,7 +121,13 @@ export function registerProductionWebhooks() {
 				return;
 			}
 
-			ResponseHelper.sendSuccessResponse(res, response.data, true, response.responseCode);
+			ResponseHelper.sendSuccessResponse(
+				res,
+				response.data,
+				true,
+				response.responseCode,
+				response.headers,
+			);
 		},
 	);
 
@@ -141,7 +153,13 @@ export function registerProductionWebhooks() {
 				return;
 			}
 
-			ResponseHelper.sendSuccessResponse(res, response.data, true, response.responseCode);
+			ResponseHelper.sendSuccessResponse(
+				res,
+				response.data,
+				true,
+				response.responseCode,
+				response.headers,
+			);
 		},
 	);
 
@@ -173,7 +191,13 @@ export function registerProductionWebhooks() {
 				return;
 			}
 
-			ResponseHelper.sendSuccessResponse(res, response.data, true, response.responseCode);
+			ResponseHelper.sendSuccessResponse(
+				res,
+				response.data,
+				true,
+				response.responseCode,
+				response.headers,
+			);
 		},
 	);
 
@@ -199,7 +223,13 @@ export function registerProductionWebhooks() {
 				return;
 			}
 
-			ResponseHelper.sendSuccessResponse(res, response.data, true, response.responseCode);
+			ResponseHelper.sendSuccessResponse(
+				res,
+				response.data,
+				true,
+				response.responseCode,
+				response.headers,
+			);
 		},
 	);
 
@@ -225,7 +255,13 @@ export function registerProductionWebhooks() {
 				return;
 			}
 
-			ResponseHelper.sendSuccessResponse(res, response.data, true, response.responseCode);
+			ResponseHelper.sendSuccessResponse(
+				res,
+				response.data,
+				true,
+				response.responseCode,
+				response.headers,
+			);
 		},
 	);
 }

packages/cli/src/WorkflowRunner.ts

@@ -15,6 +15,8 @@ import { IProcessMessage, WorkflowExecute } from 'n8n-core';
 
 import {
 	ExecutionError,
+	IDeferredPromise,
+	IExecuteResponsePromiseData,
 	IRun,
 	LoggerProxy as Logger,
 	Workflow,
@@ -41,9 +43,7 @@ import {
 	IBullJobResponse,
 	ICredentialsOverwrite,
 	ICredentialsTypeData,
-	IExecutionDb,
 	IExecutionFlattedDb,
-	IExecutionResponse,
 	IProcessMessageDataHook,
 	ITransferNodeTypes,
 	IWorkflowExecutionDataProcess,
@@ -51,6 +51,7 @@ import {
 	NodeTypes,
 	Push,
 	ResponseHelper,
+	WebhookHelpers,
 	WorkflowExecuteAdditionalData,
 	WorkflowHelpers,
 } from '.';
@@ -146,6 +147,7 @@ export class WorkflowRunner {
 		loadStaticData?: boolean,
 		realtime?: boolean,
 		executionId?: string,
+		responsePromise?: IDeferredPromise<IExecuteResponsePromiseData>,
 	): Promise<string> {
 		const executionsProcess = config.get('executions.process') as string;
 		const executionsMode = config.get('executions.mode') as string;
@@ -153,11 +155,17 @@ export class WorkflowRunner {
 		if (executionsMode === 'queue' && data.executionMode !== 'manual') {
 			// Do not run "manual" executions in bull because sending events to the
 			// frontend would not be possible
-			executionId = await this.runBull(data, loadStaticData, realtime, executionId);
+			executionId = await this.runBull(
+				data,
+				loadStaticData,
+				realtime,
+				executionId,
+				responsePromise,
+			);
 		} else if (executionsProcess === 'main') {
-			executionId = await this.runMainProcess(data, loadStaticData, executionId);
+			executionId = await this.runMainProcess(data, loadStaticData, executionId, responsePromise);
 		} else {
-			executionId = await this.runSubprocess(data, loadStaticData, executionId);
+			executionId = await this.runSubprocess(data, loadStaticData, executionId, responsePromise);
 		}
 
 		const postExecutePromise = this.activeExecutions.getPostExecutePromise(executionId);
@@ -200,6 +208,7 @@ export class WorkflowRunner {
 		data: IWorkflowExecutionDataProcess,
 		loadStaticData?: boolean,
 		restartExecutionId?: string,
+		responsePromise?: IDeferredPromise<IExecuteResponsePromiseData>,
 	): Promise<string> {
 		if (loadStaticData === true && data.workflowData.id) {
 			data.workflowData.staticData = await WorkflowHelpers.getStaticDataById(
@@ -256,6 +265,15 @@ export class WorkflowRunner {
 				executionId,
 				true,
 			);
+
+			additionalData.hooks.hookFunctions.sendResponse = [
+				async (response: IExecuteResponsePromiseData): Promise<void> => {
+					if (responsePromise) {
+						responsePromise.resolve(response);
+					}
+				},
+			];
+
 			additionalData.sendMessageToUI = WorkflowExecuteAdditionalData.sendMessageToUI.bind({
 				sessionId: data.sessionId,
 			});
@@ -341,11 +359,15 @@ export class WorkflowRunner {
 		loadStaticData?: boolean,
 		realtime?: boolean,
 		restartExecutionId?: string,
+		responsePromise?: IDeferredPromise<IExecuteResponsePromiseData>,
 	): Promise<string> {
 		// TODO: If "loadStaticData" is set to true it has to load data new on worker
 
 		// Register the active execution
 		const executionId = await this.activeExecutions.add(data, undefined, restartExecutionId);
+		if (responsePromise) {
+			this.activeExecutions.attachResponsePromise(executionId, responsePromise);
+		}
 
 		const jobData: IBullJobData = {
 			executionId,
@@ -545,6 +567,7 @@ export class WorkflowRunner {
 		data: IWorkflowExecutionDataProcess,
 		loadStaticData?: boolean,
 		restartExecutionId?: string,
+		responsePromise?: IDeferredPromise<IExecuteResponsePromiseData>,
 	): Promise<string> {
 		let startedAt = new Date();
 		const subprocess = fork(pathJoin(__dirname, 'WorkflowRunnerProcess.js'));
@@ -653,6 +676,10 @@ export class WorkflowRunner {
 			} else if (message.type === 'end') {
 				clearTimeout(executionTimeout);
 				this.activeExecutions.remove(executionId, message.data.runData);
+			} else if (message.type === 'sendResponse') {
+				if (responsePromise) {
+					responsePromise.resolve(WebhookHelpers.decodeWebhookResponse(message.data.response));
+				}
 			} else if (message.type === 'sendMessageToUI') {
 				// eslint-disable-next-line @typescript-eslint/no-unsafe-call
 				WorkflowExecuteAdditionalData.sendMessageToUI.bind({ sessionId: data.sessionId })(

packages/cli/src/WorkflowRunnerProcess.ts

@@ -10,6 +10,7 @@ import { IProcessMessage, UserSettings, WorkflowExecute } from 'n8n-core';
 import {
 	ExecutionError,
 	IDataObject,
+	IExecuteResponsePromiseData,
 	IExecuteWorkflowInfo,
 	ILogger,
 	INodeExecutionData,
@@ -33,6 +34,7 @@ import {
 	IWorkflowExecuteProcess,
 	IWorkflowExecutionDataProcessWithExecution,
 	NodeTypes,
+	WebhookHelpers,
 	WorkflowExecuteAdditionalData,
 	WorkflowHelpers,
 } from '.';
@@ -200,6 +202,15 @@ export class WorkflowRunnerProcess {
 			workflowTimeout <= 0 ? undefined : Date.now() + workflowTimeout * 1000,
 		);
 		additionalData.hooks = this.getProcessForwardHooks();
+
+		additionalData.hooks.hookFunctions.sendResponse = [
+			async (response: IExecuteResponsePromiseData): Promise<void> => {
+				await sendToParentProcess('sendResponse', {
+					response: WebhookHelpers.encodeWebhookResponse(response),
+				});
+			},
+		];
+
 		additionalData.executionId = inputData.executionId;
 
 		// eslint-disable-next-line @typescript-eslint/no-explicit-any

packages/core/src/NodeExecuteFunctions.ts

@@ -22,6 +22,7 @@ import {
 	ICredentialsExpressionResolveValues,
 	IDataObject,
 	IExecuteFunctions,
+	IExecuteResponsePromiseData,
 	IExecuteSingleFunctions,
 	IExecuteWorkflowInfo,
 	IHttpRequestOptions,
@@ -1635,6 +1636,9 @@ export function getExecuteFunctions(
 					Logger.warn(`There was a problem sending messsage to UI: ${error.message}`);
 				}
 			},
+			async sendResponse(response: IExecuteResponsePromiseData): Promise<void> {
+				await additionalData.hooks?.executeHookFunctions('sendResponse', [response]);
+			},
 			helpers: {
 				httpRequest,
 				prepareBinaryData,

packages/core/src/index.ts

@@ -12,7 +12,6 @@ export * from './ActiveWorkflows';
 export * from './ActiveWebhooks';
 export * from './Constants';
 export * from './Credentials';
-export * from './DeferredPromise';
 export * from './Interfaces';
 export * from './LoadNodeParameterOptions';
 export * from './NodeExecuteFunctions';

packages/core/test/Helpers.ts

@@ -4,6 +4,7 @@ import {
 	ICredentialDataDecryptedObject,
 	ICredentialsHelper,
 	IDataObject,
+	IDeferredPromise,
 	IExecuteWorkflowInfo,
 	INodeCredentialsDetails,
 	INodeExecutionData,
@@ -20,7 +21,7 @@ import {
 	WorkflowHooks,
 } from 'n8n-workflow';
 
-import { Credentials, IDeferredPromise, IExecuteFunctions } from '../src';
+import { Credentials, IExecuteFunctions } from '../src';
 
 export class CredentialsHelper extends ICredentialsHelper {
 	getDecrypted(

packages/core/test/WorkflowExecute.test.ts

@@ -1,6 +1,14 @@
-import { IConnections, ILogger, INode, IRun, LoggerProxy, Workflow } from 'n8n-workflow';
+import {
+	createDeferredPromise,
+	IConnections,
+	ILogger,
+	INode,
+	IRun,
+	LoggerProxy,
+	Workflow,
+} from 'n8n-workflow';
 
-import { createDeferredPromise, WorkflowExecute } from '../src';
+import { WorkflowExecute } from '../src';
 
 import * as Helpers from './Helpers';
 

packages/nodes-base/nodes/RespondToWebhook.node.ts

@@ -0,0 +1,278 @@
+import {
+	BINARY_ENCODING,
+} from 'n8n-core';
+
+import {
+	IDataObject,
+	IExecuteFunctions,
+	IN8nHttpFullResponse,
+	IN8nHttpResponse,
+	INodeExecutionData,
+	INodeType,
+	INodeTypeDescription,
+	NodeOperationError,
+} from 'n8n-workflow';
+
+export class RespondToWebhook implements INodeType {
+	description: INodeTypeDescription = {
+		displayName: 'Respond to Webhook',
+		icon: 'file:webhook.svg',
+		name: 'respondToWebhook',
+		group: ['transform'],
+		version: 1,
+		description: 'Returns data for Webhook',
+		defaults: {
+			name: 'Respond to Webhook',
+			color: '#885577',
+		},
+		inputs: ['main'],
+		outputs: ['main'],
+		credentials: [
+		],
+		properties: [
+			{
+				displayName: 'Respond With',
+				name: 'respondWith',
+				type: 'options',
+				options: [
+					{
+						name: 'First Incoming Item',
+						value: 'firstIncomingItem',
+					},
+					{
+						name: 'Text',
+						value: 'text',
+					},
+					{
+						name: 'JSON',
+						value: 'json',
+					},
+					{
+						name: 'Binary',
+						value: 'binary',
+					},
+					{
+						name: 'No Data',
+						value: 'noData',
+					},
+				],
+				default: 'firstIncomingItem',
+				description: 'The data that should be returned',
+			},
+			{
+				displayName: 'When using expressions, note that this node will only run for the first item in the input data.',
+				name: 'webhookNotice',
+				type: 'notice',
+				displayOptions: {
+					show: {
+						respondWith: [
+							'json',
+							'text',
+						],
+					},
+				},
+				default: '',
+			},
+			{
+				displayName: 'Response Body',
+				name: 'responseBody',
+				type: 'json',
+				displayOptions: {
+					show: {
+						respondWith: [
+							'json',
+						],
+					},
+				},
+				default: '',
+				placeholder: '{ "key": "value" }',
+				description: 'The HTTP Response JSON data',
+			},
+			{
+				displayName: 'Response Body',
+				name: 'responseBody',
+				type: 'string',
+				displayOptions: {
+					show: {
+						respondWith: [
+							'text',
+						],
+					},
+				},
+				default: '',
+				placeholder: 'e.g. Workflow started',
+				description: 'The HTTP Response text data',
+			},
+			{
+				displayName: 'Response Data Source',
+				name: 'responseDataSource',
+				type: 'options',
+				displayOptions: {
+					show: {
+						respondWith: [
+							'binary',
+						],
+					},
+				},
+				options: [
+					{
+						name: 'Choose Automatically From Input',
+						value: 'automatically',
+						description: 'Use if input data will contain a single piece of binary data',
+					},
+					{
+						name: 'Specify Myself',
+						value: 'set',
+						description: 'Enter the name of the input field the binary data will be in',
+					},
+				],
+				default: 'automatically',
+			},
+			{
+				displayName: 'Input Field Name',
+				name: 'inputFieldName',
+				type: 'string',
+				required: true,
+				default: 'data',
+				displayOptions: {
+					show: {
+						respondWith: [
+							'binary',
+						],
+						responseDataSource: [
+							'set',
+						],
+					},
+				},
+				description: 'The name of the node input field with the binary data',
+			},
+
+			{
+				displayName: 'Options',
+				name: 'options',
+				type: 'collection',
+				placeholder: 'Add Option',
+				default: {},
+				options: [
+					{
+						displayName: 'Response Code',
+						name: 'responseCode',
+						type: 'number',
+						typeOptions: {
+							minValue: 100,
+							maxValue: 599,
+						},
+						default: 200,
+						description: 'The HTTP Response code to return. Defaults to 200.',
+					},
+					{
+						displayName: 'Response Headers',
+						name: 'responseHeaders',
+						placeholder: 'Add Response Header',
+						description: 'Add headers to the webhook response',
+						type: 'fixedCollection',
+						typeOptions: {
+							multipleValues: true,
+						},
+						default: {},
+						options: [
+							{
+								name: 'entries',
+								displayName: 'Entries',
+								values: [
+									{
+										displayName: 'Name',
+										name: 'name',
+										type: 'string',
+										default: '',
+										description: 'Name of the header',
+									},
+									{
+										displayName: 'Value',
+										name: 'value',
+										type: 'string',
+										default: '',
+										description: 'Value of the header',
+									},
+								],
+							},
+						],
+					},
+				],
+			},
+		],
+	};
+
+	execute(this: IExecuteFunctions): Promise<INodeExecutionData[][]> {
+		const items = this.getInputData();
+
+		const respondWith = this.getNodeParameter('respondWith', 0) as string;
+		const options = this.getNodeParameter('options', 0, {}) as IDataObject;
+
+		const headers = {} as IDataObject;
+		if (options.responseHeaders) {
+			for (const header of (options.responseHeaders as IDataObject).entries as IDataObject[]) {
+				if (typeof header.name !== 'string') {
+					header.name = header.name?.toString();
+				}
+				headers[header.name?.toLowerCase() as string] = header.value?.toString();
+			}
+		}
+
+		let responseBody: IN8nHttpResponse;
+		if (respondWith === 'json') {
+			const responseBodyParameter = this.getNodeParameter('responseBody', 0) as string;
+			if (responseBodyParameter) {
+				responseBody = JSON.parse(responseBodyParameter);
+			}
+		} else if (respondWith === 'firstIncomingItem') {
+			responseBody = items[0].json;
+		} else if (respondWith === 'text') {
+			responseBody = this.getNodeParameter('responseBody', 0) as string;
+		} else if (respondWith === 'binary') {
+			const item = this.getInputData()[0];
+
+			if (item.binary === undefined) {
+				throw new NodeOperationError(this.getNode(), 'No binary data exists on the first item!');
+			}
+
+			let responseBinaryPropertyName: string;
+
+			const responseDataSource = this.getNodeParameter('responseDataSource', 0) as string;
+
+			if (responseDataSource === 'set') {
+				responseBinaryPropertyName = this.getNodeParameter('inputFieldName', 0) as string;
+			} else {
+				const binaryKeys = Object.keys(item.binary);
+				if (binaryKeys.length === 0) {
+					throw new NodeOperationError(this.getNode(), 'No binary data exists on the first item!');
+				}
+				responseBinaryPropertyName = binaryKeys[0];
+			}
+
+			const binaryData = item.binary[responseBinaryPropertyName];
+
+			if (binaryData === undefined) {
+				throw new NodeOperationError(this.getNode(), `No binary data property "${responseBinaryPropertyName}" does not exists on item!`);
+			}
+
+			if (headers['content-type']) {
+				headers['content-type'] = binaryData.mimeType;
+			}
+			responseBody = Buffer.from(binaryData.data, BINARY_ENCODING);
+		} else if (respondWith !== 'noData') {
+			throw new NodeOperationError(this.getNode(), `The Response Data option "${respondWith}" is not supported!`);
+		}
+
+		const response: IN8nHttpFullResponse = {
+			body: responseBody,
+			headers,
+			statusCode: options.responseCode as number || 200,
+		};
+
+		this.sendResponse(response);
+
+		return this.prepareOutputData(items);
+	}
+
+}

packages/nodes-base/nodes/Wait.node.ts

@@ -304,6 +304,11 @@ export class Wait implements INodeType {
 						value: 'lastNode',
 						description: 'Returns data of the last executed node',
 					},
+					{
+						name: 'Response Node finishes',
+						value: 'responseNode',
+						description: 'Returns data the response node did set',
+					},
 				],
 				default: 'onReceived',
 				description: 'When and how to respond to the webhook',

packages/nodes-base/nodes/Webhook.node.ts

@@ -9,7 +9,6 @@ import {
 	INodeType,
 	INodeTypeDescription,
 	IWebhookResponseData,
-	NodeApiError,
 	NodeOperationError,
 } from 'n8n-workflow';
 
@@ -143,10 +142,54 @@ export class Webhook implements INodeType {
 				required: true,
 				description: 'The path to listen to.',
 			},
+			{
+				displayName: 'Respond',
+				name: 'responseMode',
+				type: 'options',
+				options: [
+					{
+						name: 'Immediately',
+						value: 'onReceived',
+						description: 'As soon as this node executes',
+					},
+					{
+						name: 'When last node finishes',
+						value: 'lastNode',
+						description: 'Returns data of the last-executed node',
+					},
+					{
+						name: 'Using \'Respond to Webhook\' node',
+						value: 'responseNode',
+						description: 'Response defined in that node',
+					},
+				],
+				default: 'onReceived',
+				description: 'When and how to respond to the webhook.',
+			},
+			{
+				displayName: 'Insert a \'Respond to Webhook\' node to control when and how you respond. <a href="https://docs.n8n.io/nodes/n8n-nodes-base.respondToWebhook" target="_blank">More details</a>',
+				name: 'webhookNotice',
+				type: 'notice',
+				displayOptions: {
+					show: {
+						responseMode: [
+							'responseNode',
+						],
+					},
+				},
+				default: '',
+			},
 			{
 				displayName: 'Response Code',
 				name: 'responseCode',
 				type: 'number',
+				displayOptions: {
+					hide: {
+						responseMode: [
+							'responseNode',
+						],
+					},
+				},
 				typeOptions: {
 					minValue: 100,
 					maxValue: 599,
@@ -154,25 +197,6 @@ export class Webhook implements INodeType {
 				default: 200,
 				description: 'The HTTP Response code to return',
 			},
-			{
-				displayName: 'Respond When',
-				name: 'responseMode',
-				type: 'options',
-				options: [
-					{
-						name: 'Webhook received',
-						value: 'onReceived',
-						description: 'Returns directly with defined Response Code',
-					},
-					{
-						name: 'Last node finishes',
-						value: 'lastNode',
-						description: 'Returns data of the last executed node',
-					},
-				],
-				default: 'onReceived',
-				description: 'When and how to respond to the webhook.',
-			},
 			{
 				displayName: 'Response Data',
 				name: 'responseData',

packages/nodes-base/package.json

@@ -552,6 +552,7 @@
       "dist/nodes/Reddit/Reddit.node.js",
       "dist/nodes/Redis/Redis.node.js",
       "dist/nodes/RenameKeys.node.js",
+      "dist/nodes/RespondToWebhook.node.js",
       "dist/nodes/Rocketchat/Rocketchat.node.js",
       "dist/nodes/RssFeedRead.node.js",
       "dist/nodes/Rundeck/Rundeck.node.js",

packages/workflow/src/Interfaces.ts

@@ -6,6 +6,7 @@
 import * as express from 'express';
 import * as FormData from 'form-data';
 import { URLSearchParams } from 'url';
+import { IDeferredPromise } from './DeferredPromise';
 import { Workflow } from './Workflow';
 import { WorkflowHooks } from './WorkflowHooks';
 import { WorkflowOperationError } from './WorkflowErrors';
@@ -208,6 +209,9 @@ export interface IDataObject {
 	[key: string]: GenericValue | IDataObject | GenericValue[] | IDataObject[];
 }
 
+// export type IExecuteResponsePromiseData = IDataObject;
+export type IExecuteResponsePromiseData = IDataObject | IN8nHttpFullResponse;
+
 export interface INodeTypeNameVersion {
 	name: string;
 	version: number;
@@ -324,13 +328,13 @@ export interface IHttpRequestOptions {
 	json?: boolean;
 }
 
-export type IN8nHttpResponse = IDataObject | Buffer | GenericValue | GenericValue[];
+export type IN8nHttpResponse = IDataObject | Buffer | GenericValue | GenericValue[] | null;
 
 export interface IN8nHttpFullResponse {
 	body: IN8nHttpResponse;
 	headers: IDataObject;
 	statusCode: number;
-	statusMessage: string;
+	statusMessage?: string;
 }
 
 export interface IExecuteFunctions {
@@ -371,7 +375,8 @@ export interface IExecuteFunctions {
 		outputIndex?: number,
 	): Promise<INodeExecutionData[][]>;
 	putExecutionToWait(waitTill: Date): Promise<void>;
-	sendMessageToUI(message: any): void;
+	sendMessageToUI(message: any): void; // tslint:disable-line:no-any
+	sendResponse(response: IExecuteResponsePromiseData): void; // tslint:disable-line:no-any
 	helpers: {
 		httpRequest(
 			requestOptions: IHttpRequestOptions,
@@ -492,7 +497,10 @@ export interface IPollFunctions {
 }
 
 export interface ITriggerFunctions {
-	emit(data: INodeExecutionData[][]): void;
+	emit(
+		data: INodeExecutionData[][],
+		responsePromise?: IDeferredPromise<IExecuteResponsePromiseData>,
+	): void;
 	getCredentials(type: string): Promise<ICredentialDataDecryptedObject | undefined>;
 	getMode(): WorkflowExecuteMode;
 	getActivationMode(): WorkflowActivateMode;
@@ -975,6 +983,7 @@ export interface IWorkflowExecuteHooks {
 	nodeExecuteBefore?: Array<(nodeName: string) => Promise<void>>;
 	workflowExecuteAfter?: Array<(data: IRun, newStaticData: IDataObject) => Promise<void>>;
 	workflowExecuteBefore?: Array<(workflow: Workflow, data: IRunExecutionData) => Promise<void>>;
+	sendResponse?: Array<(response: IExecuteResponsePromiseData) => Promise<void>>;
 }
 
 export interface IWorkflowExecuteAdditionalData {

packages/workflow/src/Workflow.ts

@@ -16,6 +16,8 @@
 import {
 	Expression,
 	IConnections,
+	IDeferredPromise,
+	IExecuteResponsePromiseData,
 	IGetExecuteTriggerFunctions,
 	INode,
 	INodeExecuteFunctions,
@@ -946,10 +948,23 @@ export class Workflow {
 
 			// Add the manual trigger response which resolves when the first time data got emitted
 			triggerResponse!.manualTriggerResponse = new Promise((resolve) => {
-				// eslint-disable-next-line @typescript-eslint/no-shadow
-				triggerFunctions.emit = ((resolve) => (data: INodeExecutionData[][]) => {
-					resolve(data);
-				})(resolve);
+				triggerFunctions.emit = (
+					(resolveEmit) =>
+					(
+						data: INodeExecutionData[][],
+						responsePromise?: IDeferredPromise<IExecuteResponsePromiseData>,
+					) => {
+						additionalData.hooks!.hookFunctions.sendResponse = [
+							async (response: IExecuteResponsePromiseData): Promise<void> => {
+								if (responsePromise) {
+									responsePromise.resolve(response);
+								}
+							},
+						];
+
+						resolveEmit(data);
+					}
+				)(resolve);
 			});
 
 			return triggerResponse;

packages/workflow/src/index.ts

@@ -3,6 +3,7 @@ import * as LoggerProxy from './LoggerProxy';
 import * as NodeHelpers from './NodeHelpers';
 import * as ObservableObject from './ObservableObject';
 
+export * from './DeferredPromise';
 export * from './Interfaces';
 export * from './Expression';
 export * from './NodeErrors';