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

changelog/content/experimental/unreleased.md

@@ -6,6 +6,7 @@ version:
 
 #### Scraper
 
+- {{% tag fixed %}} Improve handling of time series with missing dimensions that are requested ([#2331](https:/tomkerkhove/promitor/issues/2331))
 - {{% tag changed %}} Switch to Mariner distroless base images
 - {{% tag security %}} Patch for [CVE-2023-29331](https:/advisories/GHSA-555c-2p6r-68mm) (High)
 

src/Promitor.Core.Scraping/AzureMonitorScraper.cs

@@ -57,7 +57,9 @@ protected override async Task<ScrapeResult> ScrapeResourceAsync(string subscript
  {
  Logger.LogWarning("No metric information found for metric {MetricName} with dimension {MetricDimension}. Details: {Details}", metricsNotFoundException.Name, metricsNotFoundException.Dimension, metricsNotFoundException.Details);
 
- var measuredMetric = string.IsNullOrWhiteSpace(dimensionName) ? MeasuredMetric.CreateWithoutDimension(null) : MeasuredMetric.CreateForDimension(null, dimensionName, "unknown");
+ var measuredMetric = string.IsNullOrWhiteSpace(dimensionName) 
+ ? MeasuredMetric.CreateWithoutDimension(null) 
+ : MeasuredMetric.CreateForDimension(null, dimensionName, "unknown");
  measuredMetrics.Add(measuredMetric);
  }
 

src/Promitor.Core/Metrics/Exceptions/MissingDimensionException.cs

@@ -0,0 +1,24 @@
+using System;
+using GuardNet;
+
+namespace Promitor.Core.Metrics.Exceptions
+{
+ public class MissingDimensionException : Exception
+ {
+ /// <summary>
+ /// Constructor
+ /// </summary>
+ /// <param name="metricName">Name of the dimension</param>
+ public MissingDimensionException(string dimensionName) : base($"No value found for dimension '{dimensionName}'")
+ {
+ Guard.NotNullOrWhitespace(dimensionName, nameof(dimensionName));
+
+ DimensionName = dimensionName;
+ }
+
+ /// <summary>
+ /// Name of the dimension
+ /// </summary>
+ public string DimensionName { get; }
+ }
+}

src/Promitor.Core/Metrics/MeasuredMetric.cs

@@ -2,6 +2,7 @@
 using System.Linq;
 using GuardNet;
 using Microsoft.Azure.Management.Monitor.Fluent.Models;
+using Promitor.Core.Metrics.Exceptions;
 
 namespace Promitor.Core.Metrics
 {
@@ -63,9 +64,14 @@ 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); 
+ if(!dimensionMetadataValue.Any())
+ {
+ throw new MissingDimensionException(dimensionName);
+ }
 
- 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;
@@ -22,6 +23,7 @@
 using Promitor.Integrations.AzureMonitor.Logging;
 using Promitor.Integrations.AzureMonitor.RequestHandlers;
 using Promitor.Integrations.Azure.Authentication;
+using Promitor.Core.Metrics.Exceptions;
 
 namespace Promitor.Integrations.AzureMonitor
 {
@@ -108,9 +110,18 @@ public async Task<List<MeasuredMetric>> QueryMetricAsync(string metricName, stri
 
  // 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 (MissingDimensionException) 
+ {
+ _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 {Details}", JsonConvert.SerializeObject(timeseries)); 
+ }
  }
 
  return measuredMetrics;

src/Promitor.Tests.Unit/Metrics/MeasuredMetricTests.cs

@@ -0,0 +1,35 @@
+using System.Collections.Generic;
+using System.ComponentModel;
+using Promitor.Core.Metrics;
+using Microsoft.Azure.Management.Monitor.Fluent.Models;
+using Xunit;
+using Promitor.Core.Metrics.Exceptions;
+
+namespace Promitor.Tests.Unit.Metrics
+{
+ [Category("Unit")]
+ public class MeasuredMeticTest : UnitTest
+ {
+ [Fact]
+ public void Create_MeasuredMetric_With_Dimension_HappyPath_Succeeds()
+ {
+ var dimensionName = "dimTest";
+ var dimensionValue = "dimTest1";
+ var timeSeries = new TimeSeriesElement(new List<MetadataValue> { new(name: new LocalizableString(dimensionName), value: dimensionValue)});
+ var measuredMetric = MeasuredMetric.CreateForDimension(1, dimensionName, timeSeries);
+ Assert.Equal(measuredMetric.DimensionName, dimensionName);
+ Assert.Equal(measuredMetric.DimensionValue, dimensionValue); 
+ Assert.Equal(measuredMetric.Value, 1); 
+ }
+
+ [Fact]
+ public void Create_MeasuredMetric_Missing_Dimension_Throws_Targeted_Exception()
+ {
+ var dimensionName = "dimTest";
+ var timeSeries = new TimeSeriesElement(new List<MetadataValue> {});
+ MissingDimensionException ex = Assert.Throws<MissingDimensionException>(() => MeasuredMetric.CreateForDimension(1, dimensionName, timeSeries));
+ Assert.Equal(ex.DimensionName, dimensionName)
+ }
+ }
+
+}