refactor(test): provide means to validate metrics and observations

Some helpers are provided for introspecting metrics already (used in JWT cache tests). This change provides facilities to additionally validate emited Observation events. A new Spec module is also implemented, adding basic tests of schema cache reloading - their main goal is to excercise the new infrastructure.
2026-03-31 13:15:56 -05:00
parent ae7d4d2553
commit 8d5b1018d3
7 changed files with 198 additions and 31 deletions
@@ -0,0 +1,54 @@
+{-# LANGUAGE DataKinds           #-}
+{-# LANGUAGE FlexibleContexts    #-}
+{-# LANGUAGE MonadComprehensions #-}
+{-# LANGUAGE NamedFieldPuns      #-}
+{-# LANGUAGE TypeApplications    #-}
+
+module Observation.MetricsSpec where
+
+import           Data.List             (lookup)
+import           Network.Wai           (Application)
+import           ObsHelper
+import qualified PostgREST.AppState    as AppState
+import           PostgREST.Config      (AppConfig (configDbSchemas))
+import qualified PostgREST.Metrics     as Metrics
+import           PostgREST.Observation
+import           Prometheus            (getCounter, getVectorWith)
+import           Protolude
+import           Test.Hspec            (SpecWith, describe, it)
+import           Test.Hspec.Wai        (getState)
+
+spec :: SpecWith (SpecState, Application)
+spec = describe "Server started with metrics enabled" $ do
+  it "Should update pgrst_schema_cache_loads_total[SUCCESS]" $ do
+    SpecState{specAppState = appState, specMetrics = metrics, specObsChan} <- getState
+    let waitFor = waitForObs specObsChan
+
+    liftIO $ checkState' metrics [
+        schemaCacheLoads "SUCCESS" (+1)
+      ] $ do
+        AppState.schemaCacheLoader appState
+        waitFor (1 * sec) "SchemaCacheLoadedObs" $ \x -> [ o | o@(SchemaCacheLoadedObs{}) <- pure x]
+
+  it "Should update pgrst_schema_cache_loads_total[ERROR]" $ do
+    SpecState{specAppState = appState, specMetrics = metrics, specObsChan} <- getState
+    let waitFor = waitForObs specObsChan
+
+    liftIO $ checkState' metrics [
+        schemaCacheLoads "FAIL" (+1),
+        schemaCacheLoads "SUCCESS" (+1)
+      ] $ do
+        AppState.getConfig appState >>= \prev -> do
+          AppState.putConfig appState $ prev { configDbSchemas = pure "bad_schema" }
+          AppState.schemaCacheLoader appState
+          waitFor (1 * sec) "SchemaCacheErrorObs" $ \x -> [ o | o@(SchemaCacheErrorObs{}) <- pure x]
+          AppState.putConfig appState prev
+
+        -- wait up to 2 secs so that retry can happen
+        waitFor (2 * sec) "SchemaCacheLoadedObs" $ \x -> [ o | o@(SchemaCacheLoadedObs{}) <- pure x]
+
+  where
+    -- prometheus-client api to handle vectors is convoluted
+    schemaCacheLoads label = expectField @"schemaCacheLoads" $
+      fmap (maybe (0::Int) round . lookup label) . (`getVectorWith` getCounter)
+    sec = 1000000