From 4d838a730c770fa2e80e98aabcdfc4fe7ef0cc60 Mon Sep 17 00:00:00 2001
From: Aneil Mallavarapu <aneilmallavar@gmail.com>
Date: Thu, 29 Nov 2018 04:07:23 -0800
Subject: [PATCH] Fixes #332, the EventEmitter memory leak warning

The bug was due to reusing transports when creating new loggers.
Also upgrades to winston 3.1.0 which fixes a different EventEmitter issue
which results in the same warning.
---
 app-backend/package.json         |  2 +-
 app-backend/src/common/logger.ts | 33 +++++++++++++++++---------------
 app-backend/yarn.lock            | 21 +++++++++++++++++---
 3 files changed, 37 insertions(+), 19 deletions(-)

diff --git a/app-backend/package.json b/app-backend/package.json
index 66c05778..77221aeb 100644
--- a/app-backend/package.json
+++ b/app-backend/package.json
@@ -102,7 +102,7 @@
     "seqvarnomjs": "git+ssh://git@github.com/precisely/seqvarnomjs#1.3.3",
     "slugify": "^1.3.0",
     "smart-report": "git+ssh://git@github.com/precisely/smart-report.git#2.0.8",
-    "winston": "^3.0.0",
+    "winston": "^3.1.0",
     "winston-cloudwatch": "^2.0.2"
   },
   "devDependencies": {
diff --git a/app-backend/src/common/logger.ts b/app-backend/src/common/logger.ts
index c405635b..e073adb3 100644
--- a/app-backend/src/common/logger.ts
+++ b/app-backend/src/common/logger.ts
@@ -14,23 +14,11 @@ const { format } = winston;
 const WinstonCloudWatch = require('winston-cloudwatch');
 
 export const LOG_DATA_SEP = '\t|\t';
+import * as fs from 'fs';
 
 type FormatInfo = { timestamp: number, level: number | string, message: string };
 const shouldLogToCloudWatchAggregate = process.env.STAGE !== 'prod' && !isOffline;
 const LOG_LEVEL = (process.env.LOG_LEVEL || 'info').toLowerCase();
-const LOG_TRANSPORTS = shouldLogToCloudWatchAggregate ? [
-  new winston.transports.Console(),
-
-  // Adds Cloudwatch logging at
-  // /precisely/web/{stage}/aggregated-log
-  new WinstonCloudWatch({ // aggregate view across all lambda fns
-    level: LOG_LEVEL,
-    logGroupName: `/precisely/web/${process.env.STAGE}`,
-    logStreamName: 'aggregated-log'
-  })
-] : [
-  new winston.transports.Console()
-];
 
 function makeFormatter(colorize: boolean, requestId?: string) {
   const plugins = [ format.timestamp(), format.splat() ];
@@ -46,7 +34,6 @@ function makeFormatter(colorize: boolean, requestId?: string) {
       (info: FormatInfo) => `${info.timestamp} ${info.level}: ${info.message}${LOG_DATA_SEP}`)
     );
   }
-
   return format.combine(... plugins);
 }
 
@@ -69,10 +56,26 @@ export interface Logger {
   shouldLog(level: number | string): boolean;
 }
 
+function makeTransports() {
+  return shouldLogToCloudWatchAggregate ? [
+    new winston.transports.Console(),
+  
+    // Adds Cloudwatch logging at
+    // /precisely/web/{stage}/aggregated-log
+    new WinstonCloudWatch({ // aggregate view across all lambda fns
+      level: LOG_LEVEL,
+      logGroupName: `/precisely/web/${process.env.STAGE}`,
+      logStreamName: 'aggregated-log'
+    })
+  ] : [
+    new winston.transports.Console()
+  ];
+}
+
 export function makeLogger(requestId?: string): Logger {
   const shouldColorize = isOffline;
   const logger = winston.createLogger({
-    transports: LOG_TRANSPORTS,
+    transports: makeTransports(),
     level: LOG_LEVEL,
     format: makeFormatter(shouldColorize, requestId)
   });
diff --git a/app-backend/yarn.lock b/app-backend/yarn.lock
index 972bb4ee..dd5a1573 100644
--- a/app-backend/yarn.lock
+++ b/app-backend/yarn.lock
@@ -1060,7 +1060,7 @@ async-limiter@~1.0.0:
 
 async@1.x, async@^1.5.2:
   version "1.5.2"
-  resolved "http://registry.npmjs.org/async/-/async-1.5.2.tgz#ec6a61ae56480c0c3cb241c95618e20892f9672a"
+  resolved "https://registry.yarnpkg.com/async/-/async-1.5.2.tgz#ec6a61ae56480c0c3cb241c95618e20892f9672a"
   integrity sha1-7GphrlZIDAw8skHJVhjiCJL5Zyo=
 
 async@2.5.0:
@@ -4714,6 +4714,21 @@ istanbul@^0.4.5:
   version "0.4.5"
   resolved "https://registry.yarnpkg.com/istanbul/-/istanbul-0.4.5.tgz#65c7d73d4c4da84d4f3ac310b918fb0b8033733b"
   integrity sha1-ZcfXPUxNqE1POsMQuRj7C4Azczs=
+  dependencies:
+    abbrev "1.0.x"
+    async "1.x"
+    escodegen "1.8.x"
+    esprima "2.7.x"
+    glob "^5.0.15"
+    handlebars "^4.0.1"
+    js-yaml "3.x"
+    mkdirp "0.5.x"
+    nopt "3.x"
+    once "1.x"
+    resolve "1.1.x"
+    supports-color "^3.1.0"
+    which "^1.1.1"
+    wordwrap "^1.0.0"
 
 isurl@^1.0.0-alpha5:
   version "1.0.0"
@@ -6019,7 +6034,7 @@ mixin-deep@^1.2.0:
 
 mkdirp@0.5.x, mkdirp@0.x, "mkdirp@>=0.5 0", mkdirp@^0.5.0, mkdirp@^0.5.1, mkdirp@~0.5.0:
   version "0.5.1"
-  resolved "http://registry.npmjs.org/mkdirp/-/mkdirp-0.5.1.tgz#30057438eac6cf7f8c4767f38648d6697d75c903"
+  resolved "https://registry.yarnpkg.com/mkdirp/-/mkdirp-0.5.1.tgz#30057438eac6cf7f8c4767f38648d6697d75c903"
   integrity sha1-MAV0OOrGz3+MR2fzhkjWaX11yQM=
   dependencies:
     minimist "0.0.8"
@@ -9224,7 +9239,7 @@ winston-transport@^4.2.0:
     readable-stream "^2.3.6"
     triple-beam "^1.2.0"
 
-winston@^3.0.0:
+winston@^3.1.0:
   version "3.1.0"
   resolved "https://registry.yarnpkg.com/winston/-/winston-3.1.0.tgz#80724376aef164e024f316100d5b178d78ac5331"
   integrity sha512-FsQfEE+8YIEeuZEYhHDk5cILo1HOcWkGwvoidLrDgPog0r4bser1lEIOco2dN9zpDJ1M88hfDgZvxe5z4xNcwg==