server/pro: add prometheus metrics for caching

PR-URL: https://github.com/hasura/graphql-engine-mono/pull/9140
Co-authored-by: Rob Dominguez <24390149+robertjdominguez@users.noreply.github.com>
GitOrigin-RevId: 945a6e650f8b8f1b04647d6f5a632ce767298229

docs/docs/enterprise/metrics.mdx

@@ -84,6 +84,16 @@ Current number of active subscriptions, representing the subscription load on th
 | Type   | Gauge                         |
 | Labels | none                          |
 
+### Hasura Cache requests count
+
+Tracks cache hit and miss requests, which helps in monitoring and optimizing cache utilization.
+
+|        |                              |
+| ------ | ---------------------------- |
+| Name   | `hasura_cache_request_count` |
+| Type   | Counter                      |
+| Labels | `status`: hit \| miss        |
+
 ### Hasura cron events invocation total
 
 Total number of cron events invoked, representing the number of invocations made for cron events.

server/src-lib/Hasura/Server/Prometheus.hs

@@ -5,6 +5,7 @@ module Hasura.Server.Prometheus
   ( PrometheusMetrics (..),
     GraphQLRequestMetrics (..),
     EventTriggerMetrics (..),
+    CacheRequestMetrics (..),
     makeDummyPrometheusMetrics,
     ConnectionsGauge,
     Connections (..),
@@ -52,7 +53,8 @@ data PrometheusMetrics = PrometheusMetrics
     pmActionBytesSent :: Counter,
     pmScheduledTriggerMetrics :: ScheduledTriggerMetrics,
     pmSubscriptionMetrics :: SubscriptionMetrics,
-    pmWebsocketMsgQueueTimeSeconds :: Histogram
+    pmWebsocketMsgQueueTimeSeconds :: Histogram,
+    pmCacheRequestMetrics :: CacheRequestMetrics
   }
 
 data GraphQLRequestMetrics = GraphQLRequestMetrics
@@ -102,6 +104,11 @@ data SubscriptionMetrics = SubscriptionMetrics
     submActiveStreamingPollersInError :: Gauge
   }
 
+data CacheRequestMetrics = CacheRequestMetrics
+  { crmCacheHits :: Counter,
+    crmCacheMisses :: Counter
+  }
+
 -- | Create dummy mutable references without associating them to a metrics
 -- store.
 makeDummyPrometheusMetrics :: IO PrometheusMetrics
@@ -117,6 +124,7 @@ makeDummyPrometheusMetrics = do
   pmScheduledTriggerMetrics <- makeDummyScheduledTriggerMetrics
   pmSubscriptionMetrics <- makeDummySubscriptionMetrics
   pmWebsocketMsgQueueTimeSeconds <- Histogram.new []
+  pmCacheRequestMetrics <- makeDummyCacheRequestMetrics
   pure PrometheusMetrics {..}
 
 makeDummyGraphQLRequestMetrics :: IO GraphQLRequestMetrics
@@ -170,6 +178,12 @@ makeDummySubscriptionMetrics = do
   submActiveStreamingPollersInError <- Gauge.new
   pure SubscriptionMetrics {..}
 
+makeDummyCacheRequestMetrics :: IO CacheRequestMetrics
+makeDummyCacheRequestMetrics = do
+  crmCacheHits <- Counter.new
+  crmCacheMisses <- Counter.new
+  pure CacheRequestMetrics {..}
+
 --------------------------------------------------------------------------------
 
 -- | A mutable reference for atomically sampling the number of websocket