init

.gitignore

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+.idea
+vscode
+node_modules

Dockerfile

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+FROM node:alpine
+
+ARG PORT
+ENV PORT=$PORT
+
+COPY . .
+RUN npm install && npm run build
+
+CMD ["node", "dist/main.js"]
+EXPOSE $PORT

package.json

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+{
+  "name": "stock-exporter",
+  "version": "1.0.0",
+  "description": "Export stock prices to prometheus",
+  "main": "main.ts",
+  "scripts": {
+    "build": "tsc",
+    "start": "ts-node src/main.ts"
+  },
+  "author": "ztimson",
+  "license": "MIT",
+  "dependencies": {
+    "@ztimson/utils": "^0.23.22",
+    "compression": "^1.7.5",
+    "cors": "^2.8.5",
+    "express": "^4.21.2"
+  },
+  "devDependencies": {
+    "@types/compression": "^1.7.5",
+    "@types/cors": "^2.8.17",
+    "@types/express": "^5.0.0",
+    "@types/node": "^22.13.0",
+    "ts-node": "^11.0.0-beta.1",
+    "typescript": "^5.8.3"
+  }
+}

src/environment.ts

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+import packageJson from '../package.json';
+import process from 'node:process';
+
+export const environment = {
+	port: process.env['port'] ?? 3000,
+	production: !process.env.NODE_ENV || ['prod', 'production'].includes(process.env.NODE_ENV.toLowerCase()),
+	tickers: process.env['tickers']?.split(',') ?? [],
+	token: process.env['token'],
+	version: packageJson.version
+}

src/error.middleware.ts

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+import {BadRequestError, CustomError, ForbiddenError, InternalServerError, Logger} from '@ztimson/utils';
+import {Response, NextFunction} from 'express';
+import {environment} from './environment';
+
+export class PermissionsError extends ForbiddenError {
+	constructor(message?: string) {
+		super(message.replace(/^.+?:/g, 'Permissions required:'));
+	}
+}
+
+export class ValidationError extends BadRequestError {
+	constructor(message: string = 'Unknown') {
+		super(`Validation Error: ${message}`);
+	}
+
+	static from(err: any) {
+		const f = err.fields;
+		const k = Object.keys(f);
+		return new ValidationError(f[k[0]].message);
+	}
+}
+
+export const errorHandler = fn => (req: any, res: Response, next: NextFunction) => {
+	Promise.resolve(fn(req, res, next)).catch(next);
+};
+
+const logger = new Logger();
+export const errorMiddleware = (err: Error | CustomError, req?: any, resp?: Response, next?: NextFunction) => {
+	const e: CustomError = CustomError.instanceof(err) ? <CustomError>err :
+		/Requires (one of|all):/g.test(err.message) ? PermissionsError.from(err) :
+			err?.stack?.includes('SqliteError') ? BadRequestError.from(err) :
+			err?.stack?.includes('ValidateError') ? ValidationError.from(err) :
+			InternalServerError.from(err);
+
+	const clientError = e.code >= 400 && e.code < 500;
+	if(req) logger[clientError ? (environment.production ? 'debug' : 'warn') : 'error'](`[${req.ipV4}] ${req.method} ${req.url ? decodeURI(req.url) : null} -> ${e.code}`);
+	if(!clientError || !environment.production) {
+		const message = (e.stack || `${e.message} (No Stack Trace)`);
+		logger[clientError ? 'warn' : 'error'](message);
+	}
+
+	if(resp) {
+		resp['logged'] = true;
+		resp.statusMessage = e.message.replaceAll('\n', ' ');
+		resp.contentType('application/json').status(e.code).send({
+			method: req?.method,
+			url: req?.url,
+			code: e.code,
+			timestamp: (new Date()).toISOString(),
+			message: e.message,
+			stack: environment.production ? undefined : e.stack,
+		});
+	}
+}

src/logger.middleware.ts

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+import {Response, NextFunction} from 'express';
+import {environment} from './environment';
+
+export function formatIp(ip: string) {
+	if(!ip) return null;
+	const ipv4 = ip.split(':').splice(-1)[0];
+	if(ipv4 == '1') return '127.0.0.1';
+	return ipv4;
+}
+
+export function loggerMiddleware(req: any, resp: Response, next: NextFunction) {
+	req.start = new Date().getTime();
+	req.ipV4 = formatIp(req.ip);
+
+	if(req.path == '/api/healthcheck' && environment.production)
+		return next();
+
+	console.debug(`[${req.ipV4}] ${req.method} ${decodeURI(req.url)}`);
+	resp.on('finish', () => {
+		if(resp['logged']) return;
+		let units = 'ms', elapsed: any = new Date().getTime() - req.start;
+		if(elapsed > 1000) {
+			units = 's';
+			elapsed = (elapsed / 1000).toFixed(1);
+		}
+		if(units == 's' && elapsed > 100) {
+			units = 'm';
+			elapsed = (elapsed / 60).toFixed(1);
+		}
+		const serverError = resp.statusCode >= 500 && resp.statusCode < 600;
+		const clientError = resp.statusCode >= 400 && resp.statusCode < 500;
+		console[serverError ? 'error' : (clientError && !environment.production) ? 'warn' : 'log'](`(${elapsed}${units}) [${req.ipV4}] ${req?.session?.user ? `(${req.session?.user?.username}) ` : ''}${req.method} ${decodeURI(req.url)} -> ${resp.statusCode}`);
+	});
+
+	next();
+}

src/main.ts

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+import compression from 'compression';
+import express from 'express';
+import http from 'node:http';
+import * as process from 'node:process';
+import {environment} from './environment';
+import {errorHandler, errorMiddleware} from './error.middleware';
+import {loggerMiddleware} from './logger.middleware';
+
+if(!environment.token) throw new Error('Please provide a Finnhub token');
+if(!environment.tickers.length) throw new Error('Please provide a CSV list of tickers');
+
+const app = express();
+const httpServer: http.Server = http.createServer(app);
+app.use(compression());
+app.use(loggerMiddleware);
+
+// Graceful shutdown
+let shuttingDown = false;
+['SIGHUP', 'SIGINT', 'SIGTERM'].forEach((signal) => {
+	process.on(signal, (signal, value) => {
+		if(shuttingDown) return; // Already shutting down
+		shuttingDown = true;
+		console.warn(`${signal} Received, shutting down...`);
+		httpServer.close(() => setTimeout(() => process.exit(128 + value), 1000));
+	});
+});
+
+app.get('/', errorHandler(async (req, res) => {
+	const results = await Promise.all(environment.tickers.map(ticker =>
+		fetch(`https://finnhub.io/api/v1/quote?symbol=${ticker}&token=${environment.token}`)
+			.then(resp => resp.json())));
+
+// 	const metrics = results.map(r => `# HELP stock_price_${result.symbol} Stock price for ${result.symbol}
+// # TYPE stock_price_${result.symbol} gauge
+// stock_price_${result.symbol} ${result.c}`).join('\n');
+	const metrics = JSON.stringify(results);
+
+	res.contentType('text/plain').send(metrics);
+}));
+
+// Error handling (must come last)
+app.use(errorMiddleware);
+process.on('unhandledRejection', (event) => errorMiddleware(<any>event));
+
+// Startup
+try {
+	httpServer.listen(environment.port, async () =>
+		console.log(`Listening on: http://localhost:${environment.port}`));
+} catch(err) {
+	console.error(err.message);
+	process.exit(1);
+}

tsconfig.json

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+{
+	"include": [
+		"src"
+	],
+	"compilerOptions": {
+		"baseUrl": ".",
+		"esModuleInterop": true,
+		"experimentalDecorators": true,
+		"inlineSourceMap": true,
+		"inlineSources": true,
+		"lib": ["dom", "ESNext", "DOM.Iterable"],
+		"module": "NodeNext",
+		"moduleResolution": "NodeNext",
+		"outDir": "dist",
+		"resolveJsonModule": true,
+		"rootDir": "src",
+		"skipLibCheck": true,
+		"target": "ESNext"
+	}
+}