fix: Improve AzureMonitorScraper Error Handling for Time Series Missing Requested Dimension Value

changelog/content/experimental/unreleased.md

@@ -8,6 +8,7 @@ version:
 
 - {{% tag changed %}} Switch to Mariner distroless base images
 - {{% tag security %}} Patch for [CVE-2023-29331](https://github.com/advisories/GHSA-555c-2p6r-68mm) (High)
+- {{% tag fixed %}} Better handle time series missing requested dimension in AzureMonitorClient [#2331](https://github.com/tomkerkhove/promitor/issues/2331))
 
 #### Resource Discovery
 

src/Promitor.Core/Metrics/MeasuredMetric.cs

@@ -63,9 +63,11 @@ public static MeasuredMetric CreateForDimension(double? value, string dimensionN
         {
             Guard.NotNullOrWhitespace(dimensionName, nameof(dimensionName));
             Guard.NotNull(timeseries, nameof(timeseries));
-            Guard.For<ArgumentException>(() => timeseries.Metadatavalues.Any() == false);
+
+            var dimensionMetadataValue = timeseries.Metadatavalues.Where(metadataValue => metadataValue.Name?.Value.Equals(dimensionName, StringComparison.InvariantCultureIgnoreCase) == true);            
+            Guard.For<ArgumentException>(() => dimensionMetadataValue.Count() == 0);
 
-            var dimensionValue = timeseries.Metadatavalues.Single(metadataValue => metadataValue.Name?.Value.Equals(dimensionName, StringComparison.InvariantCultureIgnoreCase) == true);
+            var dimensionValue = dimensionMetadataValue.First();
             return CreateForDimension(value, dimensionName, dimensionValue.Value);
         }
 

src/Promitor.Integrations.AzureMonitor/AzureMonitorClient.cs

@@ -7,6 +7,7 @@
 using Microsoft.Azure.Management.Monitor.Fluent.Models;
 using Microsoft.Azure.Management.ResourceManager.Fluent;
 using Microsoft.Azure.Management.ResourceManager.Fluent.Authentication;
+using Newtonsoft.Json;
 using GuardNet;
 using Microsoft.Azure.Management.ResourceManager.Fluent.Core;
 using Microsoft.Extensions.Caching.Memory;
@@ -108,9 +109,16 @@
 
                 // Get the metric value according to the requested aggregation type
                 var requestedMetricAggregate = InterpretMetricValue(aggregationType, mostRecentMetricValue);
-
-                var measuredMetric = string.IsNullOrWhiteSpace(metricDimension) ? MeasuredMetric.CreateWithoutDimension(requestedMetricAggregate) : MeasuredMetric.CreateForDimension(requestedMetricAggregate, metricDimension, timeseries);
-                measuredMetrics.Add(measuredMetric);
+                try 
+                {
+                    var measuredMetric = string.IsNullOrWhiteSpace(metricDimension) ? MeasuredMetric.CreateWithoutDimension(requestedMetricAggregate) : MeasuredMetric.CreateForDimension(requestedMetricAggregate, metricDimension, timeseries);
+                    measuredMetrics.Add(measuredMetric);
+                } 
+                catch (ArgumentException) 
+                {
+                    _logger.LogWarning("{MetricName} has return a time series with empty value for {Dimension} and the measurements will be dropped", metricName, metricDimension); 
+                    _logger.LogDebug("The violating time series has content {TimeSeriesJson}}", JsonConvert.SerializeObject(timeseries)); 
+                }
             }
 
             return measuredMetrics;