From ffaff455f6bc27323f25d6b9cc81db2ade6af45e Mon Sep 17 00:00:00 2001
From: Stefano Rivoir <stefano.rivoir@tesisquare.com>
Date: Tue, 26 Aug 2025 08:36:50 +0200
Subject: [PATCH] Add metrics for cache hit/miss Fixes #365

---
 docs/index.md         | 1 +
 lib/cache.mjs         | 6 +++++-
 lib/const.mjs         | 2 ++
 passweaver-api.mjs    | 2 ++
 test/metrics.spec.cjs | 2 ++
 5 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/docs/index.md b/docs/index.md
index 50f9546..d71bddd 100644
--- a/docs/index.md
+++ b/docs/index.md
@@ -313,6 +313,7 @@ If enabled in configuration, PassWeaver API export various metrics (along with d
   - One time tokens count (`onetimetokens_created_total`, `onetimetokens_read_total`)
   - KMS encryptions and decryptions count (`kms_encryptions_total`, `kms_decryptions_total`)
   - KMS encryptions and descriptions for each KMS (`kms_encryptions_per_kms_total`, `kms_decryptions_per_kms_total`)
+  - Cache hits and misses (`cache_hits_total`, `cache_misses_total`)
 
 ## Cache
 
diff --git a/lib/cache.mjs b/lib/cache.mjs
index ab53902..e74042a 100644
--- a/lib/cache.mjs
+++ b/lib/cache.mjs
@@ -9,6 +9,8 @@
 import * as Config from './config.mjs'
 import * as CacheNode from './cache/cache-node.mjs'
 import * as CacheRedis from './cache/cache-redis.mjs'
+import * as Metrics from './metrics.mjs'
+import * as Const from './const.mjs'
 
 let Cache
 
@@ -86,7 +88,9 @@ export async function resetItemTypes () {
  * @param {string} key Key to retreive
  */
 export async function get (user, key) {
-  return await Cache.get(`${prefix}:${key}.${user}.`)
+  const ret = await Cache.get(`${prefix}:${key}.${user}.`)
+  Metrics.counterInc(ret ? Const.METRICS_CACHE_HITS : Const.METRICS_CACHE_MISSES)
+  return ret
 }
 
 /**
diff --git a/lib/const.mjs b/lib/const.mjs
index a957024..4de9c89 100644
--- a/lib/const.mjs
+++ b/lib/const.mjs
@@ -123,3 +123,5 @@ export const METRICS_KMS_DECRYPTIONS = 'kms_decryptions_total'
 export const METRICS_KMS_ENCRYPTIONS_PER_KMS = 'kms_encryptions_per_kms_total'
 export const METRICS_KMS_DECRYPTIONS_PER_KMS = 'kms_decryptions_per_kms_total'
 export const METRICS_LOGIN_APIKEYS_PER_KEY = 'login_apikeys_per_key_total'
+export const METRICS_CACHE_HITS = 'cache_hits_total'
+export const METRICS_CACHE_MISSES = 'cache_misses_total'
diff --git a/passweaver-api.mjs b/passweaver-api.mjs
index 2243ef5..cf666ec 100644
--- a/passweaver-api.mjs
+++ b/passweaver-api.mjs
@@ -136,6 +136,8 @@ if (cfg?.enable_metrics) {
   Metrics.createCounter(Const.METRICS_KMS_ENCRYPTIONS_PER_KMS, 'Encryptions per KMS', 'kms_description')
   Metrics.createCounter(Const.METRICS_KMS_DECRYPTIONS_PER_KMS, 'Decryptions per KMS', 'kms_description')
   Metrics.createCounter(Const.METRICS_LOGIN_APIKEYS_PER_KEY, 'Login per API key', 'apikey_description')
+  Metrics.createCounter(Const.METRICS_CACHE_HITS, 'Cache hits')
+  Metrics.createCounter(Const.METRICS_CACHE_MISSES, 'Cache misses')
 }
 
 // HTTP(S) server start
diff --git a/test/metrics.spec.cjs b/test/metrics.spec.cjs
index 2641a0f..233b88e 100644
--- a/test/metrics.spec.cjs
+++ b/test/metrics.spec.cjs
@@ -33,6 +33,8 @@ describe('Metrics', function () {
     assert.match(res1.text, /kms_encryptions_per_kms_total/)
     assert.match(res1.text, /kms_decryptions_per_kms_total/)
     assert.match(res1.text, /login_apikeys_per_key_total/)
+    assert.match(res1.text, /cache_hits_total/)
+    assert.match(res1.text, /cache_misses_total/)
   })
 
   it('Check per-KMS metrics', async () => {