Support Winston as Custom Logger

README.md

@@ -6,7 +6,7 @@ JSON logging patcher for Next.js
 
 This is a library to patch the logging functions used by [Next.js](https://nextjs.org/), to have them output to `stdout` as newline-delimited JSON. This allows a Next.js application to log service events in a format that's compatible with log aggregators, without needing a custom Next.js server.
 
-This works by importing Next.js' inbuilt [logger](https://github.com/vercel/next.js/blob/canary/packages/next/build/output/log.ts) via `require`, and replacing the logging methods with custom ones. It uses [`pino`](https://github.com/pinojs/pino) to output JSON formatted logs, preserving Next.js' message and prefix, but adding timestamp, hostname and more.
+This works by importing Next.js' inbuilt [logger](https://github.com/vercel/next.js/blob/canary/packages/next/build/output/log.ts) via `require`, and replacing the logging methods with custom ones. It uses [`pino`](https://github.com/pinojs/pino) to output JSON formatted logs, preserving Next.js' message and prefix, but adding timestamp, hostname and more. Although the library was mainly developed based on `pino`, it also supports [`winston`](https://github.com/winstonjs/winston) as the logger backend. See the [Custom Logger](#custom-logger) section below for more details.
 
 From v2.0.0 onwards, this library also patches the global `console` methods, to catch additional logs that Next.js makes directly to `console`. While `pino` logging remains intact, this may cause issues with other libraries which patch or use `console` methods. Use the `next-only` preset to opt-out of this patching.
 
@@ -30,36 +30,40 @@ After:
 
 ## Usage
 
-First, install this package. You can do this with whatever Node package manager you're using in your project.
+First, install this package and `pino`. You can do this with whatever Node package manager you're using in your project.
 
 ```sh
-npm install next-logger
+npm install next-logger pino
 
 # or for Yarn
 
-yarn add next-logger
+yarn add next-logger pino
 ```
 
-Then add a [`NODE_OPTIONS`](https://nextjs.org/docs/api-reference/cli) string to your Next.js start script, to require in the logger.
-
-```sh
-NODE_OPTIONS='-r next-logger' next start
-```
-
-### Adding to `package.json` Scripts
-
-You can add this directly to your `package.json` scripts, to make it easier to start your service.
-
-```json
-"scripts": {
-  "start": "NODE_OPTIONS='-r next-logger' next start",
-  // ...your other scripts
-},
-```
+Then use the Next [Instrumentation](https://nextjs.org/docs/app/building-your-application/optimizing/instrumentation) hook to load this library.
+
+- Create `instrumentation.ts|js` file in the root directory of your project (or inside the src folder if using one)
+  ```js
+  export async function register() {
+    if (process.env.NEXT_RUNTIME === 'nodejs') {
+      await require('pino')
+      await require('next-logger')
+    }
+  }
+  ```
+- Enable the instrumentation hook in `next.config.js`
+  ```js
+  const nextConfig = {
+    // [...]
+    experimental: {
+      instrumentationHook: true,
+    },
+  }
+  ```
 
 ### Presets
 
-To support opting out of some patches, this library supports "presets". These can be used as above, with `/presets/<PRESET_NAME>` appended, for example: `NODE_OPTIONS='-r next-logger/presets/next-only'`.
+To support opting out of some patches, this library supports "presets". These can be used as above, with `/presets/<PRESET_NAME>` appended, for example: `await require("next-logger/presets/next-only")`.
 
 The following presets are supported:
 
@@ -92,19 +96,24 @@ module.exports = {
 }
 ```
 
-Or with [`winston`](https://github.com/winstonjs/winston):
+Or with `winston`:
+
+```sh
+npm install winston
+```
 
 ```js
 const { createLogger, format, transports } = require('winston')
 
-const logger = createLogger({
-  transports: [
-    new transports.Console({
-      handleExceptions: true,
-      format: format.combine(format.colorize(), format.simple()),
-    }),
-  ],
-})
+const logger = defaultConfig =>
+  createLogger({
+    transports: [
+      new transports.Console({
+        handleExceptions: true,
+        format: format.json(),
+      }),
+    ],
+  })
 
 module.exports = {
   logger,

lib/patches/console.js

@@ -1,6 +1,6 @@
 const logger = require('../logger')
 
-const getPinoMethod = consoleMethod => {
+const getLogMethod = consoleMethod => {
   const childLogger = logger.child({ name: 'console' })
 
   switch (consoleMethod) {
@@ -20,5 +20,5 @@ const getPinoMethod = consoleMethod => {
 const consoleMethods = ['log', 'debug', 'info', 'warn', 'error']
 consoleMethods.forEach(method => {
   // eslint-disable-next-line no-console
-  console[method] = getPinoMethod(method)
+  console[method] = getLogMethod(method)
 })

lib/patches/next.js

@@ -2,7 +2,7 @@ const nextLogger = require('next/dist/build/output/log')
 
 const logger = require('../logger')
 
-const getPinoMethod = nextMethod => {
+const getLogMethod = nextMethod => {
   const childLogger = logger.child({ name: 'next.js', prefix: nextMethod })
 
   switch (nextMethod) {
@@ -11,7 +11,11 @@ const getPinoMethod = nextMethod => {
     case 'warn':
       return childLogger.warn.bind(childLogger)
     case 'trace':
-      return childLogger.trace.bind(childLogger)
+      if ('trace' in childLogger) {
+        return childLogger.trace.bind(childLogger)
+      }
+      // To support Winston which doesn't have logger.trace()
+      return childLogger.debug.bind(childLogger)
     default:
       return childLogger.info.bind(childLogger)
   }
@@ -25,5 +29,5 @@ const cacheObject = require.cache[cachePath]
 cacheObject.exports = { ...cacheObject.exports }
 
 Object.keys(nextLogger.prefixes).forEach(method => {
-  Object.defineProperty(cacheObject.exports, method, { value: getPinoMethod(method) })
+  Object.defineProperty(cacheObject.exports, method, { value: getLogMethod(method) })
 })