✨ Add optional health check endpoint to worker (#2786)

* ✨ Add optional health check endpoint to worker

* 👕 Fix lint issue

* ⚡ Improve error output

packages/cli/commands/worker.ts

@@ -7,6 +7,8 @@
 /* eslint-disable @typescript-eslint/restrict-template-expressions */
 /* eslint-disable @typescript-eslint/no-unused-vars */
 // eslint-disable-next-line import/no-extraneous-dependencies
+import * as express from 'express';
+import * as http from 'http';
 import * as PCancelable from 'p-cancelable';
 
 import { Command, flags } from '@oclif/command';
@@ -14,7 +16,7 @@ import { BinaryDataManager, IBinaryDataConfig, UserSettings, WorkflowExecute } f
 
 import { IExecuteResponsePromiseData, INodeTypes, IRun, Workflow, LoggerProxy } from 'n8n-workflow';
 
-import { FindOneOptions } from 'typeorm';
+import { FindOneOptions, getConnectionManager } from 'typeorm';
 
 import * as Bull from 'bull';
 import {
@@ -328,6 +330,77 @@ export class Worker extends Command {
 						logger.error('Error from queue: ', error);
 					}
 				});
+
+				if (config.get('queue.health.active')) {
+					const port = config.get('queue.health.port') as number;
+
+					const app = express();
+					const server = http.createServer(app);
+
+					app.get(
+						'/healthz',
+						// eslint-disable-next-line consistent-return
+						async (req: express.Request, res: express.Response) => {
+							LoggerProxy.debug('Health check started!');
+
+							const connection = getConnectionManager().get();
+
+							try {
+								if (!connection.isConnected) {
+									// Connection is not active
+									throw new Error('No active database connection!');
+								}
+								// DB ping
+								await connection.query('SELECT 1');
+							} catch (e) {
+								LoggerProxy.error('No Database connection!', e);
+								const error = new ResponseHelper.ResponseError(
+									'No Database connection!',
+									undefined,
+									503,
+								);
+								return ResponseHelper.sendErrorResponse(res, error);
+							}
+
+							// Just to be complete, generally will the worker stop automatically
+							// if it loses the conection to redis
+							try {
+								// Redis ping
+								await Worker.jobQueue.client.ping();
+							} catch (e) {
+								LoggerProxy.error('No Redis connection!', e);
+								const error = new ResponseHelper.ResponseError(
+									'No Redis connection!',
+									undefined,
+									503,
+								);
+								return ResponseHelper.sendErrorResponse(res, error);
+							}
+
+							// Everything fine
+							const responseData = {
+								status: 'ok',
+							};
+
+							LoggerProxy.debug('Health check completed successfully!');
+
+							ResponseHelper.sendSuccessResponse(res, responseData, true, 200);
+						},
+					);
+
+					server.listen(port, () => {
+						console.info(`\nn8n worker health check via, port ${port}`);
+					});
+
+					server.on('error', (error: Error & { code: string }) => {
+						if (error.code === 'EADDRINUSE') {
+							console.log(
+								`n8n's port ${port} is already in use. Do you have the n8n main process running on that port?`,
+							);
+							process.exit(1);
+						}
+					});
+				}
 			} catch (error) {
 				logger.error(`Worker process cannot continue. "${error.message}"`);
 

packages/cli/config/index.ts

@@ -290,6 +290,20 @@ const config = convict({
 	},
 
 	queue: {
+		health: {
+			active: {
+				doc: 'If health checks should be enabled',
+				format: 'Boolean',
+				default: false,
+				env: 'QUEUE_HEALTH_CHECK_ACTIVE',
+			},
+			port: {
+				doc: 'Port to serve health check on if activated',
+				format: Number,
+				default: 5678,
+				env: 'QUEUE_HEALTH_CHECK_PORT',
+			},
+		},
 		bull: {
 			prefix: {
 				doc: 'Prefix for all queue keys',

packages/cli/package.json

@@ -76,7 +76,6 @@
     "concurrently": "^5.1.0",
     "jest": "^26.4.2",
     "nodemon": "^2.0.2",
-    "p-cancelable": "^2.0.0",
     "run-script-os": "^1.0.7",
     "ts-jest": "^26.3.0",
     "ts-node": "^8.9.1",
@@ -120,6 +119,7 @@
     "n8n-workflow": "~0.86.0",
     "oauth-1.0a": "^2.2.6",
     "open": "^7.0.0",
+    "p-cancelable": "^2.0.0",
     "pg": "^8.3.0",
     "prom-client": "^13.1.0",
     "request-promise-native": "^1.0.7",