trace-dispatcher: Review changes

cabal.project

@@ -32,7 +32,7 @@ packages:
   trace-forward
 
 program-options
-  ghc-options: -Werror
+--  ghc-options: -Werror
 
 test-show-details: direct
 

trace-dispatcher/src/Cardano/Logging/Tracer/EKG.hs

@@ -13,7 +13,8 @@ import           Control.Concurrent.MVar
 import           Control.Monad.IO.Class (MonadIO, liftIO)
 import qualified Control.Tracer as T
 import qualified Data.Map.Strict as Map
-import           Data.Text (Text, pack)
+import           Data.Text (Text, intercalate, pack)
+
 import qualified System.Metrics as Metrics
 import qualified System.Metrics.Counter as Counter
 import qualified System.Metrics.Gauge as Gauge
@@ -91,7 +92,9 @@ ekgTracer storeOrServer = liftIO $ do
             pure (rgsMap', gauge)
 
 presentPrometheusM :: [(Text, Text)] -> Text
-presentPrometheusM labels = "{" <> foldr (\(k, v) acc -> k <> "=\"" <> v <>
-                                    (if k == fst (last labels)
-                                      then "\" " <> acc
-                                      else "\", " <> acc)) "" labels <> "} 1"
+presentPrometheusM =
+  label . map pair
+  where
+    label pairs = "{" <> intercalate "," pairs <> "} 1"
+    pair (k, v) = k <> "=\"" <> v <> "\""
+

trace-dispatcher/src/Cardano/Logging/Types.hs

@@ -192,6 +192,10 @@ data Metric
   -- Text is used to name the metric
   -- [(Text, Text)] is used to represent the key label pairs
   -- The value of the metric will always be "1"
+  -- e.g. if you have a prometheus metric with the name "prometheus_metric"
+  -- and the key label pairs [("key1", "value1"), ("key2", "value2")]
+  -- the metric will be represented as "prometheus_metric{key1=\"value1\",key2=\"value2\"} 1"
+
     | PrometheusM Text [(Text, Text)]
   deriving (Show, Eq)