feat/df-1026: createLogger() as a singleton

package.json

@@ -46,7 +46,7 @@
   "license": "SEE LICENSE IN LICENSE",
   "dependencies": {
     "@aws-sdk/client-sns": "^3.997.0",
-    "@defra/forms-engine-plugin": "^4.9.1",
+    "@defra/forms-engine-plugin": "^4.10.0",
     "@defra/forms-model": "^3.0.647",
     "@defra/hapi-tracing": "^1.30.0",
     "@elastic/ecs-pino-format": "^1.5.0",

src/index.ts

@@ -1,11 +1,9 @@
 import { getErrorMessage } from '@defra/forms-model'
 
 import { config } from '~/src/config/index.js'
-import { createLogger } from '~/src/server/common/helpers/logging/logger.js'
+import { logger } from '~/src/server/common/helpers/logging/logger.js'
 import { createServer } from '~/src/server/index.js'
 
-const logger = createLogger()
-
 process.on('unhandledRejection', (err) => {
   logger.info('Unhandled rejection')
   logger.error(

src/server/common/helpers/logging/logger.ts

@@ -2,6 +2,10 @@ import { pino } from 'pino'
 
 import { loggerOptions } from '~/src/server/common/helpers/logging/logger-options.js'
 
-export function createLogger() {
+function createPinoLogger() {
   return pino(loggerOptions)
 }
+
+// Singleton logger instance - pino adds 'exit' listeners to process,
+// so we reuse a single instance to avoid MaxListenersExceededWarning
+export const logger = createPinoLogger()

src/server/common/helpers/redis-client.js

@@ -2,7 +2,7 @@ import { getErrorMessage } from '@defra/forms-model'
 import { Cluster, Redis } from 'ioredis'
 
 import { config } from '~/src/config/index.js'
-import { createLogger } from '~/src/server/common/helpers/logging/logger.js'
+import { logger } from '~/src/server/common/helpers/logging/logger.js'
 
 /**
  * Setup Redis and provide a redis client
@@ -11,8 +11,6 @@ import { createLogger } from '~/src/server/common/helpers/logging/logger.js'
  * Out in the wild - Elasticache / Redis Cluster with username and password
  */
 export function buildRedisClient() {
-  const logger = createLogger()
-
   const port = 6379
   const db = 0
   const redisConfig = config.get('redis')

src/server/messaging/formAdapterEventPublisher.ts

@@ -3,10 +3,9 @@ import { formAdapterSubmissionMessagePayloadSchema } from '@defra/forms-engine-p
 import { type FormAdapterSubmissionMessagePayload } from '@defra/forms-engine-plugin/engine/types.js'
 
 import { config } from '~/src/config/index.js'
-import { createLogger } from '~/src/server/common/helpers/logging/logger.js'
+import { logger } from '~/src/server/common/helpers/logging/logger.js'
 import { getSNSClient } from '~/src/server/messaging/sns.js'
 
-const logger = createLogger()
 const snsAdapterTopicArn = config.get('snsAdapterTopicArn')
 const snsFormTopicArnMapRaw = config.get('snsFormTopicArnMap')
 const snsFormTopicArnMap: Record<string, string> = snsFormTopicArnMapRaw

src/server/messaging/publish-base.js

@@ -1,11 +1,9 @@
 import { PublishCommand } from '@aws-sdk/client-sns'
 
 import { config } from '~/src/config/index.js'
-import { createLogger } from '~/src/server/common/helpers/logging/logger.js'
+import { logger } from '~/src/server/common/helpers/logging/logger.js'
 import { getSNSClient } from '~/src/server/messaging/sns.js'
 
-const logger = createLogger()
-
 const snsSaveTopicArn = config.get('snsSaveTopicArn')
 
 const client = getSNSClient()

src/server/plugins/nunjucks/context.js

@@ -8,9 +8,7 @@ import { StatusCodes } from 'http-status-codes'
 import pkg from '~/package.json' with { type: 'json' }
 import { parseCookieConsent } from '~/src/common/cookies.js'
 import { config } from '~/src/config/index.js'
-import { createLogger } from '~/src/server/common/helpers/logging/logger.js'
-
-const logger = createLogger()
+import { logger } from '~/src/server/common/helpers/logging/logger.js'
 
 /** @type {Record<string, string> | undefined} */
 let webpackManifest

src/server/routes/save-and-exit.js

@@ -11,7 +11,7 @@ import * as Hoek from '@hapi/hoek'
 import { StatusCodes } from 'http-status-codes'
 import Joi from 'joi'
 
-import { createLogger } from '~/src/server/common/helpers/logging/logger.js'
+import { logger } from '~/src/server/common/helpers/logging/logger.js'
 import { createJoiError } from '~/src/server/helpers/error-helper.js'
 import { publishSaveAndExitEvent } from '~/src/server/messaging/publish.js'
 import {
@@ -38,7 +38,6 @@ import {
   getSaveAndExitDetails,
   validateSaveAndExitCredentials
 } from '~/src/server/services/formsService.js'
-const logger = createLogger()
 
 const maxInvalidPasswordAttempts = 5
 

src/server/services/outputService.test.js

@@ -13,10 +13,10 @@ import {
 jest.mock('@defra/forms-engine-plugin/engine/helpers.js')
 jest.mock('@defra/forms-engine-plugin/engine/outputFormatters/index.js')
 jest.mock('~/src/server/common/helpers/logging/logger.ts', () => ({
-  createLogger: jest.fn(() => ({
+  logger: {
     info: jest.fn(),
     error: jest.fn()
-  }))
+  }
 }))
 jest.mock('~/src/server/messaging/formAdapterEventPublisher.ts')
 jest.mock('~/src/server/services/formsService.js')

src/server/services/outputService.ts

@@ -17,12 +17,10 @@ import {
   type SubmitResponsePayload
 } from '@defra/forms-model'
 
-import { createLogger } from '~/src/server/common/helpers/logging/logger.js'
+import { logger } from '~/src/server/common/helpers/logging/logger.js'
 import { publishFormAdapterEvent } from '~/src/server/messaging/formAdapterEventPublisher.js'
 import { getFormMetadataById } from '~/src/server/services/formsService.js'
 
-const logger = createLogger()
-
 /**
  * Output service for handling form submission notifications
  */