feat: Add functionality to customize log layout and introduce JSON logger

package.json

@@ -124,6 +124,7 @@
     "lodash.groupby": "^4.6.0",
     "lodash.sortby": "^4.7.0",
     "log4js": "^6.0.0",
+    "log4js-json-layout": "^2.2.3",
     "make-fetch-happen": "^11.0.0",
     "memoizee": "^0.4.15",
     "mime": "^3.0.0",

src/lib/create-config.ts

@@ -454,7 +454,9 @@ export function createConfig(options: IUnleashOptions): IUnleashConfig {
 
     const logLevel =
         options.logLevel || LogLevel[process.env.LOG_LEVEL] || LogLevel.error;
-    const getLogger = options.getLogger || getDefaultLogProvider(logLevel);
+    const logLayout = options.logLayout || process.env.LOG_LAYOUT || 'basic';
+    const getLogger =
+        options.getLogger || getDefaultLogProvider(logLevel, logLayout);
     validateLogProvider(getLogger);
 
     const server: IServerOption = mergeAll([

src/lib/logger.ts

@@ -1,4 +1,5 @@
-import { configure, getLogger } from 'log4js';
+import { configure, getLogger, addLayout, Layout } from 'log4js';
+import jsonLayout from 'log4js-json-layout';
 
 export type LogProvider = (category?: string) => Logger;
 
@@ -20,10 +21,16 @@ export interface Logger {
 
 export function getDefaultLogProvider(
     logLevel: LogLevel = LogLevel.error,
+    logLayout: string | Layout = 'basic',
 ): LogProvider {
+    addLayout('json', jsonLayout);
+
+    const layout =
+        typeof logLayout === 'string' ? { type: logLayout } : logLayout;
+
     configure({
         appenders: {
-            console: { type: 'console' },
+            console: { type: 'console', layout: layout },
         },
         categories: {
             default: { appenders: ['console'], level: logLevel },

src/lib/types/option.ts

@@ -5,6 +5,7 @@ import { ILegacyApiTokenCreate } from './models/api-token';
 import { IFlagResolver, IExperimentalOptions, IFlags } from './experimental';
 import SMTPTransport from 'nodemailer/lib/smtp-transport';
 import { IUnleashServices } from './services';
+import { Layout } from 'log4js';
 
 export interface ISSLOption {
     rejectUnauthorized: boolean;
@@ -109,6 +110,7 @@ export interface IUnleashOptions {
     session?: Partial<ISessionOption>;
     getLogger?: LogProvider;
     logLevel?: LogLevel;
+    logLayout?: string | Layout;
     server?: Partial<IServerOption>;
     versionCheck?: Partial<IVersionOption>;
     telemetry?: boolean;

website/docs/using-unleash/deploy/configuring-unleash.md

@@ -98,6 +98,7 @@ unleash.start(unleashOptions);
 - ~~eventHook~~ (`function(event, data)`) - (_deprecated in Unleash 4.3_ in favor of the [Webhook integration](/reference/integrations/webhook.md). **Removed in Unleash 5**) If provided, this function will be invoked whenever a feature is mutated. The possible values for `event` are `'feature-created'`, `'feature-archived'` and `'feature-revived'`. The `data` argument contains information about the mutation. Its fields are `type` (string) - the event type (same as `event`); `createdBy` (string) - the user who performed the mutation; `data` - the contents of the change. The contents in `data` differs based on the event type; For `'feature-archived'` and `'feature-revived'`, the only field will be `name` - the name of the feature. For `'feature-created'` the data follows a schema defined in the code [here](https://github.com/Unleash/unleash/blob/7b7f0b84e8cddd5880dcf29c231672113224b9a7/src/lib/schema/feature-schema.ts#L77). See an [api here](/reference/api/legacy/unleash/admin/events).
 - **getLogger** (function) - Used to register a [custom log provider](#how-do-i-configure-the-log-output).
 - **logLevel** (`debug` | `info` | `warn` | `error` | `fatal`) - The lowest level to log at, also configurable using environment variable `LOG_LEVEL`.
+- **logLayout** - A [log layout](https://log4js-node.github.io/log4js-node/layouts.html) to apply to log4js. May be the name of a layout or a complete layout object if further configuration is needed. The `LOG_LAYOUT` environment may also be used if only the layout name is required. Besides the bundled layouts provided by log4js, the [`json`](https://github.com/id0Sch/log4js-json-layout) layout is supported for structured logs.
 - **enableRequestLogger** (boolean) - use this to enable logging for requested urls and response codes (default: false).
 - **preHook** (function) - this is a hook if you need to provide any middlewares to express before `unleash` adds any. Express app instance is injected as first argument.
 - **preRouterHook** (function) - use this to register custom express middlewares before the `unleash` specific routers are added.

yarn.lock

@@ -2325,6 +2325,11 @@ colors@1.0.x:
   resolved "https://registry.yarnpkg.com/colors/-/colors-1.0.3.tgz#0433f44d809680fdeb60ed260f1b0c262e82a40b"
   integrity sha512-pFGrxThWcWQ2MsAz6RtgeWe4NK2kUE1WfsrvvlctdII745EW9I0yflqhe7++M5LEc7bV2c/9/5zc8sFcpL0Drw==
 
+colors@^1.1.2:
+  version "1.4.0"
+  resolved "https://registry.yarnpkg.com/colors/-/colors-1.4.0.tgz#c50491479d4c1bdaed2c9ced32cf7c7dc2360f78"
+  integrity sha512-a+UqTh4kgZg/SlGvfbzDHpgRu7AAQOmmqRHJnxhRZICKFUT91brVhNNt58CMWU9PsBbv3PDCZUHbVxuDiH2mtA==
+
 combined-stream@^1.0.6, combined-stream@^1.0.8, combined-stream@~1.0.6:
   version "1.0.8"
   resolved "https://registry.yarnpkg.com/combined-stream/-/combined-stream-1.0.8.tgz#c3d45a8b34fd730631a110a8a2520682b31d5a7f"
@@ -4669,7 +4674,7 @@ lodash.sortby@^4.7.0:
   resolved "https://registry.yarnpkg.com/lodash.sortby/-/lodash.sortby-4.7.0.tgz#edd14c824e2cc9c1e0b0a1b42bb5210516a42438"
   integrity sha512-HDWXG8isMntAyRF5vZ7xKuEvOhT4AhlRt/3czTSjvGUxjYCBVRQY48ViDHyfYz9VIoBkW4TMGQNapx+l3RUwdA==
 
-lodash@^4.17.21:
+lodash@^4.17.21, lodash@^4.17.4:
   version "4.17.21"
   resolved "https://registry.yarnpkg.com/lodash/-/lodash-4.17.21.tgz#679591c564c3bffaae8454cf0b3df370c3d6911c"
   integrity sha512-v2kDEe57lecTulaDIuNTPy3Ry4gLGJ6Z1O3vE1krgXZNrsQ+LFTGHVxVjcXPs17LhbZVGedAJv8XZ1tvj5FvSg==
@@ -4689,6 +4694,14 @@ log-update@^4.0.0:
     slice-ansi "^4.0.0"
     wrap-ansi "^6.2.0"
 
+log4js-json-layout@^2.2.3:
+  version "2.2.3"
+  resolved "https://registry.yarnpkg.com/log4js-json-layout/-/log4js-json-layout-2.2.3.tgz#a9e95aff1f79e3e4bdd762a8a45fc0b5c81276cc"
+  integrity sha512-sKebdMKxF7ehqT5x760xGAI8rujDPu5dLf0p/s5e48GQYvRCkI1ycFxb6b7R8y7IZoBaXg/piL6LsMaE6Rg4gQ==
+  dependencies:
+    colors "^1.1.2"
+    lodash "^4.17.4"
+
 log4js@^6.0.0:
   version "6.9.1"
   resolved "https://registry.yarnpkg.com/log4js/-/log4js-6.9.1.tgz#aba5a3ff4e7872ae34f8b4c533706753709e38b6"