Function middleware

src/middleware/prometheus.js:38–70

(req, res, next)

	// Middleware function
	const middleware = (req, res, next) => {
		const startTime = Date.now();

		// Store original end method
		const originalEnd = res.end;

		// Override end method to capture metrics
		res.end = function (...args) {
			const duration = (Date.now() - startTime) / 1000; // Convert to seconds
			const route = req.route || req.url || "unknown";
			const method = req.method || "unknown";
			const statusCode = res.statusCode || 0;

			// Build labels object
			const labels = {
				method: config.includeMethod ? method : "HTTP",
				route: config.includePath ? route : "",
				status_code: config.includeStatusCode ? statusCode.toString() : "",
				...config.customLabels
			};

			// Record metrics
			httpRequestDuration.observe(labels, duration);
			httpRequestsTotal.inc(labels);

			// Call original end method
			originalEnd.apply(this, args);
		};

		if (typeof next === "function") {
			next();
		}
	};

	return {middleware, register};
}