feat: Export last check and last update to prometheus

.github/workflows/node.js.yml

@@ -20,14 +20,13 @@ jobs:
         # See supported Node.js release schedule at https://nodejs.org/en/about/releases/
 
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
     - name: Use Node.js ${{ matrix.node-version }}
-      uses: actions/setup-node@v3
+      uses: actions/setup-node@v4
       with:
         node-version: ${{ matrix.node-version }}
         cache: 'yarn'
     - run: yarn install --frozen-lockfile --ignore-scripts
-    - run: yarn fmt:check
-    - run: yarn lint
+    - run: yarn fmt:ci
     - run: yarn build
     - run: yarn test --coverage

.github/workflows/release_changelog.yml

@@ -10,10 +10,10 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout code
-        uses: actions/checkout@v2
+        uses: actions/checkout@v4
       - name: Build changelog
         id: github_release
-        uses: metcalfc/changelog-generator@v0.4.4
+        uses: metcalfc/changelog-generator@v4.3.1
         with:
           myToken: ${{ secrets.GITHUB_TOKEN }}
       - name: Create release

.nvmrc

@@ -1 +1 @@
-v14.19
+16

biome.json

@@ -0,0 +1,82 @@
+{
+  "$schema": "https://biomejs.dev/schemas/1.8.3/schema.json",
+  "linter": {
+    "enabled": true,
+    "rules": {
+      "recommended": true,
+      "correctness": {
+        "noUnsafeOptionalChaining": "off",
+        "useExhaustiveDependencies": "off",
+        "noUnusedImports": "warn",
+        "useJsxKeyInIterable": "off"
+      },
+      "complexity": {
+        "noBannedTypes": "off",
+        "noUselessConstructor": "off",
+        "useOptionalChain": "warn",
+        "noStaticOnlyClass": "off",
+        "noForEach": "off"
+      },
+      "style": {
+        "noNonNullAssertion": "off",
+        "noInferrableTypes": "off",
+        "noUnusedTemplateLiteral": "off",
+        "useSingleVarDeclarator": "off",
+        "noUselessElse": "off",
+        "useNodejsImportProtocol": "off"
+      },
+      "suspicious": {
+        "noExplicitAny": "off",
+        "noExtraNonNullAssertion": "off",
+        "noRedeclare": "off",
+        "noPrototypeBuiltins": "off",
+        "noConfusingVoidType": "off",
+        "noArrayIndexKey": "off",
+        "noThenProperty": "off",
+        "noExportsInTest": "off"
+      },
+      "performance": {
+        "noAccumulatingSpread": "off",
+        "noDelete": "off"
+      }
+    },
+    "ignore": [
+      "node_modules",
+      "docker",
+      "setupJest.js",
+      "dist",
+      "build",
+      ".docusaurus",
+      "CHANGELOG.md",
+      "./package.json",
+      "tsconfig.json"
+    ]
+  },
+  "organizeImports": {
+    "enabled": false
+  },
+  "formatter": {
+    "indentStyle": "space",
+    "ignore": [
+      "node_modules",
+      "dist",
+      "build",
+      "./package.json",
+      "tsconfig.json"
+    ],
+    "indentWidth": 4
+  },
+  "javascript": {
+    "formatter": {
+      "semicolons": "always",
+      "quoteStyle": "single",
+      "jsxQuoteStyle": "single",
+      "indentWidth": 4
+    }
+  },
+  "json": {
+    "formatter": {
+      "indentWidth": 2
+    }
+  }
+}

package.json

@@ -7,13 +7,13 @@
   "scripts": {
     "build": "tsc --pretty",
     "example": "npm run build && node example",
-    "lint": "eslint ./src",
+    "lint": "biome lint ./src --write",
     "test": "jest",
     "updateSnapshots": "jest -u",
     "prepare": "npm run build",
     "dev": "ENABLE_OAS=true ts-node-dev src/start.ts",
-    "fmt": "prettier src --write --loglevel warn",
-    "fmt:check": "prettier src --check"
+    "fmt": "biome format ./src --write",
+    "fmt:ci": "biome ci ./src"
   },
   "repository": {
     "type": "git",
@@ -41,59 +41,37 @@
     "@unleash/express-openapi": "^0.3.0",
     "compression": "^1.7.4",
     "cors": "^2.8.5",
-    "express": "^4.18.2",
-    "json-schema-to-ts": "^2.3.0",
-    "openapi-types": "^11.0.0",
-    "qs": "^6.9.7",
+    "express": "^4.19.2",
+    "json-schema-to-ts": "^3.1.0",
+    "openapi-types": "^12.1.3",
+    "prom-client": "^15.1.3",
+    "qs": "^6.12.3",
     "type-is": "^1.6.18",
     "unleash-client": "^6.1.1"
   },
   "devDependencies": {
     "@apidevtools/swagger-parser": "10.1.0",
-    "@babel/core": "^7.24.4",
-    "@types/compression": "^1.7.2",
-    "@types/cors": "^2.8.12",
+    "@babel/core": "^7.25.2",
+    "@biomejs/biome": "^1.8.3",
+    "@types/compression": "^1.7.5",
+    "@types/cors": "^2.8.17",
     "@types/express": "^4.17.13",
-    "@types/jest": "^27.5.0",
+    "@types/jest": "^29.5.12",
     "@types/node": "18.7.14",
-    "@types/supertest": "^2.0.12",
-    "@types/type-is": "^1.6.3",
-    "@typescript-eslint/eslint-plugin": "^5.22.0",
-    "@typescript-eslint/parser": "^5.22.0",
-    "babel-jest": "^28.0.3",
-    "eslint": "^8.14.0",
-    "eslint-config-airbnb-base": "^15.0.0",
-    "eslint-config-airbnb-typescript": "^17.0.0",
-    "eslint-config-prettier": "^8.5.0",
-    "eslint-plugin-import": "^2.26.0",
-    "eslint-plugin-prettier": "^4.0.0",
-    "jest": "^28.0.3",
-    "prettier": "^2.6.2",
-    "semver": "^7.3.7",
-    "supertest": "^6.2.3",
-    "ts-jest": "^28.0.1",
-    "ts-node-dev": "^1.1.8",
-    "typescript": "^4.6.4"
-  },
-  "prettier": {
-    "proseWrap": "never",
-    "singleQuote": true,
-    "tabWidth": 4,
-    "trailingComma": "all",
-    "overrides": [
-      {
-        "files": "*.{json,yaml,yml,md}",
-        "options": {
-          "tabWidth": 2
-        }
-      }
-    ]
+    "@types/supertest": "^6.0.2",
+    "@types/type-is": "^1.6.6",
+    "babel-jest": "^28.1.3",
+    "jest": "^29.7.0",
+    "semver": "^7.6.3",
+    "supertest": "^7.0.0",
+    "ts-jest": "^29.2.4",
+    "ts-node-dev": "^2.0.0",
+    "typescript": "^5.5.4"
   },
   "resolutions": {
-    "wrap-ansi": "7.0.0",
-    "string-width": "4.1.0",
     "qs": "^6.9.7",
     "json5": "^2.2.2",
     "cookiejar": "^2.1.4"
-  }
+  },
+  "packageManager": "yarn@1.22.22+sha1.ac34549e6aa8e7ead463a7407e1c7390f61a6610"
 }

src/app.ts

@@ -1,8 +1,8 @@
 import compression from 'compression';
-import express, { Application } from 'express';
+import express, { type Application } from 'express';
 import cors from 'cors';
-import { IClient } from './client';
-import { createProxyConfig, IProxyOption } from './config';
+import type { IClient } from './client';
+import { createProxyConfig, type IProxyOption } from './config';
 
 import UnleashProxy from './unleash-proxy';
 import { OpenApiService } from './openapi/openapi-service';
@@ -48,6 +48,7 @@ export function createApp(
     const corsOptions = config.cors;
     app.use(cors(corsOptions));
 
+    // @ts-expect-error - Seems to be an incompatibility with express's own middleware here
     app.use(compression());
 
     app.use(

src/client.ts

@@ -1,10 +1,11 @@
 import EventEmitter from 'events';
-import { Context, Unleash, Variant } from 'unleash-client';
-import { FeatureInterface } from 'unleash-client/lib/feature';
-import Metrics from 'unleash-client/lib/metrics';
+import { Context, Unleash, UnleashEvents, Variant } from "unleash-client";
+import type { FeatureInterface } from 'unleash-client/lib/feature';
+import type Metrics from 'unleash-client/lib/metrics';
 import { getDefaultVariant } from 'unleash-client/lib/variant';
-import { IProxyConfig } from './config';
-import { Logger } from './logger';
+import type { IProxyConfig } from './config';
+import type { Logger } from './logger';
+import { lastMetricsFetch, lastMetricsUpdate } from "./prometheus";
 
 export type FeatureToggleStatus = {
     name: string;
@@ -72,11 +73,20 @@ class Client extends EventEmitter implements IClient {
 
         this.metrics.on('error', (msg) => this.logger.error(`metrics: ${msg}`));
         this.unleash.on('error', (msg) => this.logger.error(msg));
+
         this.unleash.on('ready', () => {
             this.emit('ready');
             this.ready = true;
             this.metrics.start();
         });
+        this.unleash.on(UnleashEvents.Unchanged, () => {
+            lastMetricsFetch.set(new Date().getTime());
+        });
+        this.unleash.on(UnleashEvents.Changed, () => {
+            const updated = new Date().getTime();
+            lastMetricsFetch.set(updated);
+            lastMetricsUpdate.set(updated);
+        });
     }
 
     setUnleashApiToken(unleashApiToken: string): void {

src/config.ts

@@ -1,12 +1,16 @@
-import { CorsOptions } from 'cors';
-import { Application } from 'express';
-import { ClientFeaturesResponse, Strategy, TagFilter } from 'unleash-client';
-import { BootstrapOptions } from 'unleash-client/lib/repository/bootstrap-provider';
-import { Logger, LogLevel, SimpleLogger } from './logger';
+import type { CorsOptions } from 'cors';
+import type { Application } from 'express';
+import type {
+    ClientFeaturesResponse,
+    Strategy,
+    TagFilter,
+} from 'unleash-client';
+import type { BootstrapOptions } from 'unleash-client/lib/repository/bootstrap-provider';
+import { type Logger, type LogLevel, SimpleLogger } from './logger';
 import { generateInstanceId } from './util';
-import { HttpOptions } from 'unleash-client/lib/http-options';
-import { StorageProvider } from 'unleash-client/lib/repository/storage-provider';
-import { ContextEnricher } from './enrich-context';
+import type { HttpOptions } from 'unleash-client/lib/http-options';
+import type { StorageProvider } from 'unleash-client/lib/repository/storage-provider';
+import type { ContextEnricher } from './enrich-context';
 
 export interface ServerSideSdkConfig {
     tokens: string[];
@@ -310,7 +314,7 @@ export function createProxyConfig(option: IProxyOption): IProxyConfig {
         process.env.UNLEASH_INSTANCE_ID ||
         generateInstanceId();
 
-    let proxyBasePath = sanitizeBasePath(
+    const proxyBasePath = sanitizeBasePath(
         option.proxyBasePath || process.env.PROXY_BASE_PATH,
     );
     return {

src/content-type-checker.ts

@@ -1,4 +1,4 @@
-import { RequestHandler } from 'express';
+import type { RequestHandler } from 'express';
 import { hasBody, is } from 'type-is';
 
 const DEFAULT_ACCEPTED_CONTENT_TYPE = 'application/json';

src/context-middleware.ts

@@ -1,6 +1,6 @@
-import { NextFunction, Request, Response } from 'express';
+import type { NextFunction, Request, Response } from 'express';
 import { createContext } from './create-context';
-import { ContextEnricher, enrichContext } from './enrich-context';
+import { type ContextEnricher, enrichContext } from './enrich-context';
 
 const POST = 'POST';
 const GET = 'GET';

src/create-client.ts

@@ -1,4 +1,4 @@
-import { IProxyConfig } from './config';
+import type { IProxyConfig } from './config';
 import Client from './client';
 import { initialize, Unleash } from 'unleash-client';
 import Metrics from 'unleash-client/lib/metrics';
@@ -23,7 +23,7 @@ export const createSingletonClient = (config: IProxyConfig): Client => {
         customHeadersFunction,
         bootstrap: config.bootstrap,
         storageProvider: config.storageProvider,
-        ...(!!config.httpOptions ? { httpOptions: config.httpOptions } : {}),
+        ...(config.httpOptions ? { httpOptions: config.httpOptions } : {}),
     });
 
     const metrics = new Metrics({
@@ -35,7 +35,7 @@ export const createSingletonClient = (config: IProxyConfig): Client => {
         metricsJitter: config.metricsJitter,
         url: config.unleashUrl,
         customHeadersFunction,
-        ...(!!config.httpOptions ? { httpOptions: config.httpOptions } : {}),
+        ...(config.httpOptions ? { httpOptions: config.httpOptions } : {}),
     });
 
     return new Client(config, unleash, metrics);
@@ -60,7 +60,7 @@ export const createNewClient = (config: IProxyConfig): Client => {
         customHeadersFunction,
         bootstrap: config.bootstrap,
         storageProvider: config.storageProvider,
-        ...(!!config.httpOptions ? { httpOptions: config.httpOptions } : {}),
+        ...(config.httpOptions ? { httpOptions: config.httpOptions } : {}),
     });
 
     const metrics = new Metrics({
@@ -72,7 +72,7 @@ export const createNewClient = (config: IProxyConfig): Client => {
         metricsJitter: config.metricsJitter,
         url: config.unleashUrl,
         customHeadersFunction,
-        ...(!!config.httpOptions ? { httpOptions: config.httpOptions } : {}),
+        ...(config.httpOptions ? { httpOptions: config.httpOptions } : {}),
     });
 
     return new Client(config, unleash, metrics);

src/create-context.ts

@@ -1,12 +1,12 @@
 /* eslint-disable prefer-object-spread */
-import { Context } from 'unleash-client';
+import type { Context } from 'unleash-client';
 
 function tryParseDate(dateString: string | undefined): Date | undefined {
     if (!dateString) {
         return undefined;
     }
     const parsedDate = new Date(dateString);
-    if (!isNaN(parsedDate.getTime())) {
+    if (!Number.isNaN(parsedDate.getTime())) {
         return parsedDate;
     } else {
         return undefined;

src/enrich-context.ts

@@ -1,4 +1,4 @@
-import { Context } from 'unleash-client';
+import type { Context } from 'unleash-client';
 
 export type ContextEnricher = (context: Context) => Promise<Context>;
 

src/openapi/common-responses.ts

@@ -1,4 +1,4 @@
-import { OpenAPIV3 } from 'openapi-types';
+import type { OpenAPIV3 } from 'openapi-types';
 
 export const format500ErrorMessage = (errorMessage: string): string =>
     `Whoops! We dropped the ball on this one (an unexpected error occurred): ${errorMessage}`;

src/openapi/index.ts

@@ -1,4 +1,4 @@
-import { OpenAPIV3 } from 'openapi-types';
+import type { OpenAPIV3 } from 'openapi-types';
 import { apiRequestSchema } from './spec/api-request-schema';
 import { featureSchema } from './spec/feature-schema';
 import { featuresSchema } from './spec/features-schema';