Implement OpenMetrics API endpoint

Author: zigazajc007

.env-example

@@ -51,4 +51,13 @@ LOGGER_LEVEL=3
 #          "gcp" (Google Cloud), "nginx" (Nginx), "vercel" (Vercel),
 #          "direct" (no proxy/development), "development" (dev with proxy headers)
 # Default: "direct"
-PROXY=direct
+PROXY=direct
+
+# Enable or disable OpenMetrics endpoint
+# Default: false
+OPEN_METRICS_ENABLED=false
+
+# Protect OpenMetrics API endpoint with Bearer authentication
+# Set to "none" to disable authentication (not recommended for production)
+# Default: none
+OPEN_METRICS_AUTH_TOKEN=none

README.md

@@ -83,6 +83,15 @@ LOGGER_LEVEL=3
 #          "direct" (no proxy/development), "development" (dev with proxy headers)
 # Default: "direct"
 PROXY=direct
+
+# Enable or disable OpenMetrics endpoint
+# Default: false
+OPEN_METRICS_ENABLED=false
+
+# Protect OpenMetrics API endpoint with Bearer authentication
+# Set to "none" to disable authentication (not recommended for production)
+# Default: none
+OPEN_METRICS_AUTH_TOKEN=none
 ```
 
 ### Running with Docker Compose
@@ -118,7 +127,7 @@ Health Check and Statistics
 ```json
 {
 	"program": "RabbitForexAPI",
-	"version": "4.0.3",
+	"version": "4.1.0",
 	"sourceCode": "https://github.com/Rabbit-Company/RabbitForexAPI",
 	"monitorStats": {
 		"currencyCount": 162,
@@ -135,6 +144,28 @@ Health Check and Statistics
 }
 ```
 
+### GET `/metrics`
+
+Returns metrics in OpenMetrics format for Prometheus monitoring.
+
+**Authentication**: Protected with Bearer token (configure via `OPEN_METRICS_AUTH_TOKEN` environment variable)
+
+**Response**: OpenMetrics text format
+
+**Example**:
+
+```text
+# TYPE rabbitforex_http_requests counter
+# HELP rabbitforex_http_requests Total HTTP requests
+rabbitforex_http_requests_total 0 1764012335.777
+rabbitforex_http_requests_total{endpoint="/metrics"} 52 1764012466.32
+rabbitforex_http_requests_total{endpoint="/"} 18 1764012414.1
+rabbitforex_http_requests_created 1764012335.777 1764012335.777
+rabbitforex_http_requests_created{endpoint="/metrics"} 1764012396.269 1764012466.32
+rabbitforex_http_requests_created{endpoint="/"} 1764012410.614 1764012414.1
+# EOF
+```
+
 ### GET `/openapi.json`
 
 OpenAPI specification

bun.lock

@@ -24,6 +24,8 @@ services:
       - ENABLED_CRYPTOS
       - LOGGER_LEVEL
       - PROXY
+      - OPEN_METRICS_ENABLED
+      - OPEN_METRICS_AUTH_TOKEN
     healthcheck:
       test: ["CMD", "curl", "-f", "http://localhost:3000"]
       interval: 10s

docker-compose.override.yml

@@ -23,6 +23,8 @@ services:
       - ENABLED_CRYPTOS
       - LOGGER_LEVEL
       - PROXY
+      - OPEN_METRICS_ENABLED
+      - OPEN_METRICS_AUTH_TOKEN
     healthcheck:
       test: ["CMD", "curl", "-f", "http://localhost:3000"]
       interval: 10s

docker-compose.yml

@@ -1,6 +1,6 @@
 {
 	"name": "rabbitforexapi",
-	"version": "4.0.3",
+	"version": "4.1.0",
 	"module": "src/index.ts",
 	"type": "module",
 	"private": true,
@@ -14,6 +14,7 @@
 		"typescript": "^5"
 	},
 	"dependencies": {
+		"@rabbit-company/openmetrics-client": "^2.0.1",
 		"@rabbit-company/web": "^0.16.0",
 		"@rabbit-company/web-middleware": "^0.16.0"
 	}

package.json

@@ -7,11 +7,14 @@ import { logger } from "@rabbit-company/web-middleware/logger";
 import { cors } from "@rabbit-company/web-middleware/cors";
 import pkg from "../package.json";
 import { openapi } from "./openapi";
+import { httpRequests, registry } from "./metrics";
+import { bearerAuth } from "@rabbit-company/web-middleware/bearer-auth";
 
 const host = process.env.SERVER_HOST || "0.0.0.0";
 const port = parseInt(process.env.SERVER_PORT || "3000") || 3000;
 const proxy = Object.keys(IP_EXTRACTION_PRESETS).includes(process.env.PROXY || "direct") ? (process.env.PROXY as CloudProvider) : "direct";
 const updateInterval = parseInt(process.env.UPDATE_INTERVAL || "30") || 30;
+const openMetricsEnabled = process.env.OPEN_METRICS_ENABLED === "true";
 
 const cacheControl = [
 	"public",
@@ -50,6 +53,8 @@ app.use(
 );
 
 app.get("/", (c) => {
+	httpRequests.labels({ endpoint: "/" }).inc();
+
 	return c.json(
 		{
 			program: "RabbitForexAPI",
@@ -73,11 +78,37 @@ app.get("/", (c) => {
 	);
 });
 
+if (openMetricsEnabled) {
+	app.get(
+		"/metrics",
+		bearerAuth({
+			validate(token) {
+				return token === process.env.OPEN_METRICS_AUTH_TOKEN;
+			},
+			skip() {
+				return process.env.OPEN_METRICS_AUTH_TOKEN === "none";
+			},
+		}),
+		(c) => {
+			httpRequests.labels({ endpoint: "/metrics" }).inc();
+
+			return c.text(registry.metricsText(), 200, {
+				"Content-Type": registry.contentType,
+				"Cache-Control": "no-store",
+			});
+		}
+	);
+}
+
 app.get("/openapi.json", (c) => {
+	httpRequests.labels({ endpoint: "/openapi.json" }).inc();
+
 	return c.json(openapi, 200, { "Cache-Control": "public, max-age=3600 s-maxage=3600 stale-while-revalidate=36000 stale-if-error=31536000" });
 });
 
 app.get("/v1/assets", (c) => {
+	httpRequests.labels({ endpoint: "/v1/assets" }).inc();
+
 	return c.json(
 		{
 			currencies: exchange.getSupportedCurrencies(),
@@ -97,6 +128,8 @@ app.get("/v1/assets", (c) => {
 });
 
 app.get("/v1/rates", (c) => {
+	httpRequests.labels({ endpoint: "/v1/rates" }).inc();
+
 	return c.json(
 		{
 			base: "USD",
@@ -112,6 +145,9 @@ app.get("/v1/rates", (c) => {
 
 app.get("/v1/rates/:base", (c) => {
 	const base = c.params["base"]!.toUpperCase();
+
+	httpRequests.labels({ endpoint: "/v1/rates/:base" }).inc();
+
 	return c.json(
 		{
 			base: base,
@@ -126,6 +162,8 @@ app.get("/v1/rates/:base", (c) => {
 });
 
 app.get("/v1/metals/rates", (c) => {
+	httpRequests.labels({ endpoint: "/v1/metals/rates" }).inc();
+
 	return c.json(
 		{
 			base: "USD",
@@ -143,6 +181,8 @@ app.get("/v1/metals/rates", (c) => {
 app.get("/v1/metals/rates/:base", (c) => {
 	const base = c.params["base"]!.toUpperCase();
 
+	httpRequests.labels({ endpoint: "/v1/metals/rates/:base" }).inc();
+
 	return c.json(
 		{
 			base: base,
@@ -158,6 +198,8 @@ app.get("/v1/metals/rates/:base", (c) => {
 });
 
 app.get("/v1/crypto/rates", (c) => {
+	httpRequests.labels({ endpoint: "/v1/crypto/rates" }).inc();
+
 	return c.json(
 		{
 			base: "USD",
@@ -175,6 +217,8 @@ app.get("/v1/crypto/rates", (c) => {
 app.get("/v1/crypto/rates/:base", (c) => {
 	const base = c.params["base"]!.toUpperCase();
 
+	httpRequests.labels({ endpoint: "/v1/crypto/rates/:base" }).inc();
+
 	return c.json(
 		{
 			base: base,
@@ -190,6 +234,8 @@ app.get("/v1/crypto/rates/:base", (c) => {
 });
 
 app.get("/v1/stocks/rates", (c) => {
+	httpRequests.labels({ endpoint: "/v1/stocks/rates" }).inc();
+
 	return c.json(
 		{
 			base: "USD",
@@ -207,6 +253,8 @@ app.get("/v1/stocks/rates", (c) => {
 app.get("/v1/stocks/rates/:base", (c) => {
 	const base = c.params["base"]!.toUpperCase();
 
+	httpRequests.labels({ endpoint: "/v1/stocks/rates/:base" }).inc();
+
 	return c.json(
 		{
 			base: base,
@@ -231,6 +279,7 @@ Logger.info(`Server running on http://${host}:${port}`);
 Logger.info(`Exchange rates updates every ${updateInterval}s`);
 Logger.info("Available endpoints:");
 Logger.info("	GET /                       - Health check and stats");
+Logger.info("	GET /metrics                - OpenMetrics format");
 Logger.info("	GET /openapi.json           - OpenAPI specification");
 Logger.info("	GET /v1/assets              - List all supported currencies, metals, stocks and cryptocurrencies");
 Logger.info("	GET /v1/rates               - Exchange rates for USD (default)");

src/index.ts

@@ -0,0 +1,12 @@
+import { Counter, Registry } from "@rabbit-company/openmetrics-client";
+
+export const registry = new Registry({
+	prefix: "rabbitforex",
+});
+
+export const httpRequests = new Counter({
+	name: "http_requests",
+	help: "Total HTTP requests",
+	labelNames: ["endpoint"],
+	registry,
+});

src/metrics.ts

@@ -1,29 +1,29 @@
 {
-  "compilerOptions": {
-    // Environment setup & latest features
-    "lib": ["ESNext"],
-    "target": "ESNext",
-    "module": "Preserve",
-    "moduleDetection": "force",
-    "jsx": "react-jsx",
-    "allowJs": true,
+	"compilerOptions": {
+		// Environment setup & latest features
+		"lib": ["ESNext", "DOM"],
+		"target": "ESNext",
+		"module": "Preserve",
+		"moduleDetection": "force",
+		"jsx": "react-jsx",
+		"allowJs": true,
 
-    // Bundler mode
-    "moduleResolution": "bundler",
-    "allowImportingTsExtensions": true,
-    "verbatimModuleSyntax": true,
-    "noEmit": true,
+		// Bundler mode
+		"moduleResolution": "bundler",
+		"allowImportingTsExtensions": true,
+		"verbatimModuleSyntax": true,
+		"noEmit": true,
 
-    // Best practices
-    "strict": true,
-    "skipLibCheck": true,
-    "noFallthroughCasesInSwitch": true,
-    "noUncheckedIndexedAccess": true,
-    "noImplicitOverride": true,
+		// Best practices
+		"strict": true,
+		"skipLibCheck": true,
+		"noFallthroughCasesInSwitch": true,
+		"noUncheckedIndexedAccess": true,
+		"noImplicitOverride": true,
 
-    // Some stricter flags (disabled by default)
-    "noUnusedLocals": false,
-    "noUnusedParameters": false,
-    "noPropertyAccessFromIndexSignature": false
-  }
+		// Some stricter flags (disabled by default)
+		"noUnusedLocals": false,
+		"noUnusedParameters": false,
+		"noPropertyAccessFromIndexSignature": false
+	}
 }