Prevent the engine from exiting on non-critical SMTP errors from the logger

CHANGELOG.md

@@ -2,6 +2,14 @@
 
 All changes that impact users of this module are documented in this file, in the [Common Changelog](https://common-changelog.org) format with some additional specifications defined in the CONTRIBUTING file. This codebase adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## Unreleased [patch]
+
+> Development of this release was supported by the [French Ministry for Foreign Affairs](https://www.diplomatie.gouv.fr/fr/politique-etrangere-de-la-france/diplomatie-numerique/) through its ministerial [State Startups incubator](https://beta.gouv.fr/startups/open-terms-archive.html) under the aegis of the Ambassador for Digital Affairs.
+
+### Fixed
+
+- Prevent the engine from exiting on non-critical SMTP errors from the logger
+
 ## 2.2.1 - 2024-06-07
 
 _Full changeset and discussions: [#1088](https://github.com/OpenTermsArchive/engine/pull/1088)._

package.json

@@ -99,7 +99,7 @@
     "simple-git": "^3.8.0",
     "swagger-jsdoc": "^6.2.8",
     "swagger-ui-express": "^5.0.0",
-    "winston": "^3.3.3",
+    "winston": "^3.9.0",
     "winston-mail": "^2.0.0"
   },
   "devDependencies": {

src/logger/index.js

@@ -28,14 +28,25 @@ const alignedWithColorsAndTime = combine(
   }),
 );
 
-const consoleTransport = new winston.transports.Console(({ silent: process.env.NODE_ENV === 'test' }));
+const consoleTransport = new winston.transports.Console({ silent: process.env.NODE_ENV === 'test' });
 
 const transports = [consoleTransport];
 
 const logger = winston.createLogger({
   format: alignedWithColorsAndTime,
   transports,
   rejectionHandlers: transports,
+  exitOnError: true,
+});
+
+logger.on('error', err => {
+  if ('smtp' in err) { // Check if err has an `smtp` property, even if it's undefined
+    logger.warn({ message: `Uncaught exception from SMTP mailer detected and treated as an operational error; process will continue running:\n${err.stack}` });
+
+    return; // Prevent process exit
+  }
+
+  return process.exit(1); // Exit process for other errors
 });
 
 if (config.get('@opentermsarchive/engine.logger.sendMailOnError')) {
@@ -51,7 +62,6 @@ if (config.get('@opentermsarchive/engine.logger.sendMailOnError')) {
       ssl: true,
       timeout: 30 * 1000,
       formatter: args => args[Object.getOwnPropertySymbols(args)[1]], // Returns the full error message, the same visible in the console. It is referenced in the argument object with a Symbol of which we do not have the reference but we know it is the second one.
-      exitOnError: true,
     };
 
     transports.push(new winston.transports.Mail({
@@ -67,14 +77,15 @@ if (config.get('@opentermsarchive/engine.logger.sendMailOnError')) {
         subject: `[OTA] Inaccessible content — ${os.hostname()}`,
       }));
     }
-
-    logger.configure({
-      transports,
-      rejectionHandlers: transports,
-    });
   }
 }
 
+logger.configure({
+  transports,
+  rejectionHandlers: transports,
+  exitOnError: true,
+});
+
 let recordedSnapshotsCount;
 let recordedVersionsCount;