From 1b2a4dbaaef9c024b242d6a26210d93c544f6e36 Mon Sep 17 00:00:00 2001
From: HDegroote <75906619+HDegroote@users.noreply.github.com>
Date: Thu, 1 Aug 2024 20:36:47 +0200
Subject: [PATCH] expose own metrics

---
 index.js                  | 13 +++++++++++++
 package.json              |  2 +-
 prometheus/prometheus.yml |  4 ++--
 run.js                    |  4 ++++
 test/integration.js       |  5 +++++
 5 files changed, 25 insertions(+), 3 deletions(-)

diff --git a/index.js b/index.js
index e8b4977..68f9489 100644
--- a/index.js
+++ b/index.js
@@ -15,6 +15,7 @@ const DEFAULT_PROM_TARGETS_LOC = './targets.json'
 class PrometheusDhtBridge extends ReadyResource {
   constructor (dht, server, sharedSecret, {
     keyPairSeed,
+    ownPromClient,
     _forceFlushOnClientReady = false,
     prometheusTargetsLoc = DEFAULT_PROM_TARGETS_LOC,
     entryExpiryMs = 3 * 60 * 60 * 1000,
@@ -44,6 +45,18 @@ class PrometheusDhtBridge extends ReadyResource {
       this._handleGet.bind(this)
     )
 
+    ownPromClient = ownPromClient || null
+    if (ownPromClient) {
+      this.server.get(
+        '/metrics',
+        { logLevel: serverLogLevel },
+        async function (req, reply) {
+          const metrics = await ownPromClient.register.metrics()
+          reply.send(metrics)
+        }
+      )
+    }
+
     this.promTargetsLoc = prometheusTargetsLoc
     this.aliasRpcServer = new AliasRpcServer(this.swarm, this.secret, this.putAlias.bind(this))
 
diff --git a/package.json b/package.json
index c27345c..3146357 100644
--- a/package.json
+++ b/package.json
@@ -33,7 +33,6 @@
     "hypercore-crypto": "^3.4.2",
     "hyperdht": "^6.15.1",
     "newline-decoder": "^1.0.2",
-    "prom-client": "^15.1.2",
     "standard": "^17.1.0",
     "test-tmp": "^1.2.1",
     "z32": "^1.1.0"
@@ -48,6 +47,7 @@
     "hypercore-id-encoding": "^1.3.0",
     "hyperswarm": "^4.7.15",
     "pino": "^9.2.0",
+    "prom-client": "^15.1.3",
     "protomux-rpc": "^1.5.2",
     "ready-resource": "^1.1.1",
     "safety-catch": "^1.0.2"
diff --git a/prometheus/prometheus.yml b/prometheus/prometheus.yml
index 6c0c6cb..d9cef26 100644
--- a/prometheus/prometheus.yml
+++ b/prometheus/prometheus.yml
@@ -1,8 +1,8 @@
 # This is an example config.
 
 global:
-  scrape_interval: 1s
-  evaluation_interval: 1s
+  scrape_interval: 5s
+  evaluation_interval: 5s
 
 # Source for relabeling approach: https://stackoverflow.com/questions/59866342/prometheus-dynamic-metrics-path
 scrape_configs:
diff --git a/run.js b/run.js
index 0d281c5..ee0e62b 100755
--- a/run.js
+++ b/run.js
@@ -6,6 +6,7 @@ const pino = require('pino')
 const fastify = require('fastify')
 const idEnc = require('hypercore-id-encoding')
 const goodbye = require('graceful-goodbye')
+const promClient = require('prom-client')
 
 function loadConfig () {
   const config = {
@@ -59,6 +60,8 @@ async function main () {
     _forceFlushOnClientReady
   } = loadConfig()
 
+  promClient.collectDefaultMetrics()
+
   const logger = pino({ level: logLevel })
   logger.info('Starting up Prometheus DHT bridge')
 
@@ -66,6 +69,7 @@ async function main () {
   const server = fastify({ logger })
   const bridge = new PrometheusDhtBridge(dht, server, sharedSecret, {
     keyPairSeed,
+    ownPromClient: promClient,
     prometheusTargetsLoc,
     _forceFlushOnClientReady,
     serverLogLevel
diff --git a/test/integration.js b/test/integration.js
index 749c2b4..c0ba49f 100644
--- a/test/integration.js
+++ b/test/integration.js
@@ -12,6 +12,7 @@ const promClient = require('prom-client')
 const DhtPromClient = require('dht-prom-client')
 const HyperDHT = require('hyperdht')
 const z32 = require('z32')
+const axios = require('axios')
 
 const BRIDGE_EXECUTABLE = path.join(path.dirname(__dirname), 'run.js')
 const PROMETHEUS_EXECUTABLE = path.join(path.dirname(__dirname), 'prometheus', 'prometheus')
@@ -163,6 +164,10 @@ test('Integration test, happy path', async t => {
 
   await tAliasReq
 
+  const res = await axios.get(`${bridgeHttpAddress}/metrics`)
+  t.is(res.status, 200, 'can scrape own metrics')
+  t.is(res.data.includes('nodejs_eventloop_lag_mean_seconds'), true, 'sanity check')
+
   // 3) Setup prometheus
   const promConfigFileLoc = path.join(tmpDir, 'prometheus.yml')
   await writePromConfig(promConfigFileLoc, bridgeHttpAddress, promTargetsLoc)