Prevent prometheus_quantile_summary crash without datapoints

Quantile evaluation for metrics prior to observe/_ is not a valid operation. Any metric without observation will now be skipped until data are provided.
deadtrickster · Aug 18, 2021 · b47c3d5 · b47c3d5
1 parent d3a0fdf
commit b47c3d5
Showing 1 changed file with 12 additions and 6 deletions.
diff --git a/src/metrics/prometheus_quantile_summary.erl b/src/metrics/prometheus_quantile_summary.erl
@@ -304,9 +304,12 @@ values(Registry, Name) ->
 
       MFValues = load_all_values(Registry, Name),
       ReducedMap = lists:foldl(
-        fun([L, C, S, QE], ResAcc) ->
-          {PrevCount, PrevSum, PrevQE} = maps:get(L, ResAcc, {0, 0, quantile(Configuration)}),
-          ResAcc#{L => {PrevCount + C, PrevSum + S, quantile_merge(PrevQE, QE)}}
+        fun
+          ([_, 0, _, _], ResAcc) ->
+            ResAcc; %% Ignore quantile evaluation if no data are provided
+          ([L, C, S, QE], ResAcc) ->
+            {PrevCount, PrevSum, PrevQE} = maps:get(L, ResAcc, {0, 0, quantile(Configuration)}),
+            ResAcc#{L => {PrevCount + C, PrevSum + S, quantile_merge(PrevQE, QE)}}
         end,
       #{},
       MFValues),
@@ -343,9 +346,12 @@ collect_metrics(Name, {CLabels, Labels, Registry, DU, Configuration}) ->
   #{quantiles := QNs} = Configuration,
   MFValues = load_all_values(Registry, Name),
   ReducedMap = lists:foldl(
-        fun([L, C, S, QE], ResAcc) ->
-          {PrevCount, PrevSum, PrevQE} = maps:get(L, ResAcc, {0, 0, quantile(Configuration)}),
-          ResAcc#{L => {PrevCount + C, PrevSum + S, quantile_merge(PrevQE, QE)}}
+        fun
+          ([_, 0, _, _], ResAcc) ->
+            ResAcc; %% Ignore quantile evaluation if no data are provided
+          ([L, C, S, QE], ResAcc) ->
+            {PrevCount, PrevSum, PrevQE} = maps:get(L, ResAcc, {0, 0, quantile(Configuration)}),
+            ResAcc#{L => {PrevCount + C, PrevSum + S, quantile_merge(PrevQE, QE)}}
         end,
       #{},
       MFValues),