From e3533efe796ef84fcc672553a515dfa418118678 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Rafael=20C=C3=A1rdenas?= <rafael@rafaelcr.com>
Date: Tue, 2 Jul 2024 08:57:31 -0600
Subject: [PATCH] fix: enable prometheus metrics (#7)

---
 api/src/index.ts           | 34 +++++++++++++++++++---------------
 api/src/metrics/metrics.ts | 22 ++++++++++++++++++++++
 2 files changed, 41 insertions(+), 15 deletions(-)
 create mode 100644 api/src/metrics/metrics.ts

diff --git a/api/src/index.ts b/api/src/index.ts
index 33592ba..eaeb6b8 100644
--- a/api/src/index.ts
+++ b/api/src/index.ts
@@ -1,8 +1,13 @@
-import { isProdEnv, logger, registerShutdownConfig } from '@hirosystems/api-toolkit';
+import {
+  buildPrometheusServer,
+  isProdEnv,
+  logger,
+  registerShutdownConfig,
+} from '@hirosystems/api-toolkit';
 import { buildApiServer } from './api/init';
 import { ENV } from './env';
 import { PgStore } from './pg/pg-store';
-// import { ApiMetrics } from './metrics/metrics';
+import { ApiMetrics } from './metrics/metrics';
 
 async function initApiService(db: PgStore) {
   logger.info('Initializing API service...');
@@ -17,19 +22,18 @@ async function initApiService(db: PgStore) {
 
   await fastify.listen({ host: ENV.API_HOST, port: ENV.API_PORT });
 
-  // if (isProdEnv) {
-  //   const promServer = await buildPromServer({ metrics: fastify.metrics });
-  //   registerShutdownConfig({
-  //     name: 'Prometheus Server',
-  //     forceKillable: false,
-  //     handler: async () => {
-  //       await promServer.close();
-  //     },
-  //   });
-
-  //   // ApiMetrics.configure(db);
-  //   await promServer.listen({ host: ENV.API_HOST, port: 9153 });
-  // }
+  if (isProdEnv) {
+    const promServer = await buildPrometheusServer({ metrics: fastify.metrics });
+    registerShutdownConfig({
+      name: 'Prometheus Server',
+      forceKillable: false,
+      handler: async () => {
+        await promServer.close();
+      },
+    });
+    ApiMetrics.configure(db);
+    await promServer.listen({ host: ENV.API_HOST, port: 9153 });
+  }
 }
 
 async function initApp() {
diff --git a/api/src/metrics/metrics.ts b/api/src/metrics/metrics.ts
new file mode 100644
index 0000000..d7850ad
--- /dev/null
+++ b/api/src/metrics/metrics.ts
@@ -0,0 +1,22 @@
+import * as prom from 'prom-client';
+import { PgStore } from '../pg/pg-store';
+
+export class ApiMetrics {
+  /** The most recent Bitcoin block height ingested by the API */
+  readonly runes_api_block_height: prom.Gauge;
+
+  static configure(db: PgStore): ApiMetrics {
+    return new ApiMetrics(db);
+  }
+
+  private constructor(db: PgStore) {
+    this.runes_api_block_height = new prom.Gauge({
+      name: `runes_api_block_height`,
+      help: 'The most recent Bitcoin block height ingested by the API',
+      async collect() {
+        const height = await db.getChainTipBlockHeight();
+        this.set(parseInt(height ?? '0'));
+      },
+    });
+  }
+}